NAPAC2022 - Classification: 07: Accelerator Technology

Paper	Title	Page
SUXF1	Project Management and Accelerator Development
	S. Biedron Element Aero, Chicago, USA L.M. Georgson Petrén Roddare, Lund, Sweden
	Accelerator laboratories belong to the largest research investments to be found regardless laboratory, research institute or country funding the initiatives. This impose a great responsibility on the researchers and engineers developing, building and updating research facilities. Accelerator development are important research projects and will affect many stakeholders regardless if it is a smaller upgrade of an RF system or development of a large scale FEL. Wet developing new systems project management is a core competence for every laboratory. Yet this is a knowledge area often ignored in favor skill development in areas closer to physics and technology. This can be a very expensive mistake as the value of proper project management cannot be underestimated. This half day training will give you insight in the basics of projects. What is a project and what does project management mean. And how can this be adopted in accelerator development.
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

SUZF1	Introduction to Systems Engineering Concepts
	S. Biedron Element Aero, Chicago, USA L.M. Georgson Petrén Roddare, Lund, Sweden
	Systems engineering has long been employed in defense and non-defense industries but not commonly in particle accelerator systems. The common definition of Systems Engineering is as follows "It is a transdisciplinary and integrative approach to enable the successful realization, use, and retirement of engineered systems, using systems principles and concepts, and scientific, technological, and management methods." This overview introduces participants to the fundamental principles of systems engineering and their application to the development of complex systems. Systems engineering helps address engineering challenges as well as how systems engineering is essential to project management. The overview will help the participant learn the language of methods and processes commonplace in industry. We will define the following through examples: systems, the systems development lifecycle, and methods of systems engineering, beginning with the system requirements. One example will be exploring a novel particle accelerator through systems engineering methods.
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOODE4	PW-Class Lasers for Accelerators - Overview and an Industry Perspective
	O.J. Chalus THALES LAS France, Elancourt, France
	In this presentation, we will review the current experiments done by various research group over the world on Laser assisted particle acceleration (BELLA, DESY, Weizmann…). We will spend a bit of time on the description of the laser technologies used for this. What are the specifications required for such laser, their footprint and their future development.
	Slides MOODE4 [7.209 MB]
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOYE2	LCLS-II HE vCM Test Results: Newly Developed N-Doping Treatment and Plasma Processing
	B. Giaccone Fermilab, Batavia, Illinois, USA
	This talk presents the results of the LCLS-II HE verification cryomodule (vCM), which aimed at verifing that the cryomodule is capable to meet the project specification (Q₀=2.7·10¹⁰ at 21 MV/m) with the newly developed nitrogen doping treatment. The test also carried out detailed studies on multipacting processing optimization and Q-factor quench degradation. Plasma processing was also carried out in four out of eight cavities in the cryomodule, showing its effectiveness in eliminating multipacting. These studies will be discussed.
	Slides MOYE2 [9.629 MB]
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOYE3	Experiments on a Conduction Cooled Superconducting Radio Frequency Cavity with Field Emission Cathode	16
	Y. Ji, R. Dhuley, C.J. Edwards, J.C.T. Thangaraj Fermilab, Batavia, Illinois, USA V. Korampally, D. Mihalcea, O. Mohsen, P. Piot, I. Salehinia Northern Illinois University, DeKalb, Illinois, USA
	Funding: The project is supported by DOE HEP Accelerator Stewardship award to Fermilab and Northern Illinois University To achieve Ampere-class electron beam accelerators the pulse delivery rate need to be much higher than the typical photo injector repetition rate of the order of a few kilohertz. We propose here an injector which can, in principle, generate electron bunches at the same rate as the operating RF frequency. A conduction-cooled superconducting radio frequency (SRF) cavity operating in the CW mode and housing a field emission element at its region of high axial electric field can be a viable method of generating high-repetition-rate electron bunches. In this paper, we report the development and experiments on a conduction-cooled Nb₃Sn cavity with a niobium rod intended as a field emitter support. The initial experiments demonstrate ~0.4 MV/m average accelerating gradient, which is equivalent of peak gradient of 3.2 MV/m. The measured RF cavity quality factor is 1.4 × 10⁸ slightly above our goal. The achieved field gradient is limited by the relatively low input RF power and by the poor coupling between the external power supply and the RF cavity. With ideal coupling the field gradient can be as high as 0.6 MV/m still below our goal of about 1 MV/m
	Slides MOYE3 [1.444 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOYE3
About •	Received ※ 01 August 2022 — Revised ※ 03 August 2022 — Accepted ※ 05 August 2022 — Issue date ※ 30 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOYE4	Diagnoses and Repair of a Crack in the Drift Tube LINAC Accelerating Structure at LANSCE	19
	W.C. Barkley, D.A. Bingham, M.J. Borden, J.A. Burkhart, D.J. Evans, J.T.M. Lyles, J.P. Montross, J.F. O’Hara, B.J. Roller, M. Sanchez Barrueta LANL, Los Alamos, New Mexico, USA
	Funding: Work supported by the United States Department of Energy, National Nuclear Security Agency, under contract DE-AC52-06NA25396 Many were perplexed at the inability of Module 3 at LANSCE to operate at peak power and duty factor while running production beam. During the 2018 production run, the DTL began to intermittently break down, leading to a series of root cause investigations. These analyses included eliminating the usual suspects: vacuum leak, debris in tank, driveline window, power coupler, etc. The throttling back of repetition rate from 120 to 60 Hz allowed continued production with a diminished beam, one that reduced neutron flux to three experimental areas. During the annual shutdown in 2019, a more thorough investigation involving the use of x-ray detection, high-resolution cameras and IR detection through site glass windows was performed. After a tenacious search, a 30 cm long crack was discovered in a weld at one of the ion pump port grates. Inaccessibility for welding from the outside and in a confined space, non-intrusive repairs were tried first but were unsuccessful. Ultimately, an expert welder entered the tank to weld the crack under unfamiliar welding conditions. This paper describes the diagnoses, non-intrusive solutions and ultimate repair of the crack in the accelerating structure.
	Slides MOYE4 [3.232 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOYE4
About •	Received ※ 23 July 2022 — Revised ※ 04 August 2022 — Accepted ※ 05 August 2022 — Issue date ※ 13 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOYE5	In Situ Plasma Processing of Superconducting Cavities at JLab	22
	T. Powers, N.C. Brock, T.D. Ganey JLab, Newport News, Virginia, USA
	Jefferson Lab has an ongoing R&D program in plasma processing which is close to going into production processing in the CEBAF accelerator. Plasma processing is a common technique for removing hydrocarbons from surfaces, which increases the work function and reduces the secondary emission coefficient. Unlike helium processing which relies on ion bombardment of the field emitters, plasma processing uses free oxygen produced in the plasma to break down the hydrocarbons on the surface of the cavity. The initial focus of the effort was processing C100 cavities by injecting RF power into the HOM coupler ports. Results from processing cryomodule in the cryomodule test bunker as well as vertical test results will be presented. We plan to start processing cryomodules in the CEBAF tunnel within the next year. The goal will be to improve the operational gradients and the energy margin of the linacs. This work will describe the systems and methods used at JLAB for processing cavities using an argon oxygen gas mixture. Before and after plasma processing results will also be presented.
	Slides MOYE5 [2.679 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOYE5
About •	Received ※ 01 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 01 October 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOYE6	Spin-Polarized Electron Photoemission and Detection Studies	26
	A.C. Rodriguez Alicea, R. Palai University of Puerto Rico, Rio Piedras Campus, San Juan, Puerto Rico O. Chubenko, S.S. Karkare Arizona State University, Tempe, USA L. Cultrera BNL, Upton, New York, USA
	Funding: Brookhaven National Laboratory and the Department of Energy of United States under contract No. DE-SC0012704 Also, the Center for Bright Beams, NSF award PHY-1549132. The experimental investigation of new photocathode ma- terials is time-consuming, expensive, and difficult to accom- plish. Computational modelling offers fast and inexpensive ways to explore new materials, and operating conditions, that could potentially enhance the efficiency of polarized electron beam photocathodes. We report on Monte-Carlo simulation of electron spin polarization (ESP) and quantum efficiency (QE) of bulk GaAs at 2, 77, and 300 K using the data obtained from Density Functional Theory (DFT) cal- culations at the corresponding temperatures. The simulated results of ESP and QE were compared with reported exper- imental measurements, and showed good agreement at 77 and 300 K.
	Slides MOYE6 [6.235 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOYE6
About •	Received ※ 03 August 2022 — Revised ※ 07 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 04 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPA21	Effect of Electropolishing on Nitrogen Doped and Undoped Niobium Surfaces	93
	V. Chouhan, F. Furuta, M. Martinello, T.J. Ring, G. Wu Fermilab, Batavia, Illinois, USA
	Cold electropolishing (EP) of a nitrogen-doped (N-doped) niobium (Nb) superconducting RF (SRF) cavity was found to improve its quality factor. In order to understand the effect of EP temperature on N-doped and undoped surfaces, a systematic EP study was conducted with 2/0 N-doped and heat-treated Nb samples in a beaker. The Nb samples were electropolished at different surface temperatures ranging from 0 to 42 C. The results showed that the doped surface was susceptible to the sample temperature during EP. EP resulted in the surface pitting on the doped samples where the number density of pits increased at a higher temperature. The surface results were compared with the surface of cutouts from a 9-cell cavity which was 2/0 N-doped and electropolished. This paper shows de-tailed surface features of the N-doped and undoped Nb surfaces electropolished at different temperatures.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA21
About •	Received ※ 20 July 2022 — Revised ※ 24 July 2022 — Accepted ※ 09 August 2022 — Issue date ※ 11 August 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPA22	Study on Electropolishing Conditions for 650 MHz Niobium SRF Cavity	97
	V. Chouhan, D.J. Bice, F. Furuta, M. Martinello, M.K. Ng, H. Park, T.J. Ring, G. Wu Fermilab, Batavia, Illinois, USA B.M. Guilfoyle, M.P. Kelly, T. Reid ANL, Lemont, Illinois, USA
	The PIP II linear accelerator includes different types of niobium SRF cavities including 650 MHz elliptical low (0.61) and high (0.92) beta cavities. The elliptical cavity surface is processed with the electropolishing method. The elliptical cavities especially the low-beta 650 MHz cavities showed a rough equator surface after the EP was performed with the standard EP conditions. This work was focused to study the effect of different EP parameters, including cathode surface area, temperature and voltage, and optimize them to improve the cavity surface.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA22
About •	Received ※ 02 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 03 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPA23	Tests of the Extended Range SRF Cavity Tuners for the LCLS-II HE Project	100
	C. Contreras-Martinez, T.T. Arkan, A.T. Cravatta, B.D. Hartsell, J.A. Kaluzny, T.N. Khabiboulline, Y.M. Pischalnikov, S. Posen, G.V. Romanov, J.C. Yun Fermilab, Batavia, Illinois, USA
	The LCLS-II HE superconducting linac will produce multi-energy beams by supporting multiple undulator lines simultaneously. This could be achieved by using the cavity SRF tuner in the off-frequency detune mode. This off-frequency operation method was tested in the verification cryomodule (vCM) and CM 1 at Fermilab at 2 K. In both cases, the tuners achieved a frequency shift of -565±80 kHz. This study will discuss cavity frequency during each step as it is being assembled in the cryomodule string and finally when it is being tested at 2 K. Tracking the cavity frequency helped enable the tuners to reach this large frequency shift. The specific procedures of tuner setting during assembly will be presented.
	Poster MOPA23 [0.654 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA23
About •	Received ※ 03 August 2022 — Revised ※ 11 August 2022 — Accepted ※ 19 August 2022 — Issue date ※ 31 August 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPA24	LCLS-II and HE Cryomodule Microphonics at CMTF at Fermilab	103
	C. Contreras-Martinez, B.E. Chase, A.T. Cravatta, J.A. Einstein-Curtis, E.R. Harms, J.P. Holzbauer, J.N. Makara, S. Posen, R. Wang Fermilab, Batavia, Illinois, USA L.R. Doolittle LBNL, Berkeley, California, USA
	Microphonics causes the cavity to detune. This study discusses the microphonics of 16 cryomodules, 14 for LCLS-II and 2 for LCLS-II HE tested at CMTF. The peak detuning, as well as the RMS detuning for each cryomodule, will be discussed. For each cryomodule, the data was taken with enough soaking time to prevent any thermalization effects which can show up in the detuning. Each data capture taken was 30 minutes or longer and sampled at 1 kHz.
	Poster MOPA24 [1.428 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA24
About •	Received ※ 03 August 2022 — Revised ※ 10 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 20 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPA25	Simulated Lorentz Force Detuning Compensation with a Double Lever Tuner on a Dressed ILC/1.3 GHz Cavity at Room Temperature	106
	C. Contreras-Martinez, Y.M. Pischalnikov, J.C. Yun Fermilab, Batavia, Illinois, USA
	Pulsed SRF linacs with high accelerating gradients experience large frequency shifts caused by Lorentz force detuning (LFD). A piezoelectric actuator with a resonance control algorithm can maintain the cavity frequency at the nominal level thus reducing the RF power. This study uses a double lever tuner with a piezoelectric actuator for compensation and another piezoelectric actuator to simulate the effects of the Lorentz force pulse. A double lever tuner has an advantage by increasing the stiffness of the cavity-tuner system thus reducing the effects of LFD. The tests are conducted at room temperature and with a dressed 1.3 GHz 9-cell cavity.
	Poster MOPA25 [0.931 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA25
About •	Received ※ 03 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 13 August 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPA27	Validation of the 650 MHz SRF Tuner on the Low and High Beta Cavities for PIP-II at 2 K	109
	C. Contreras-Martinez, S.K. Chandrasekaran, S. Cheban, G.V. Eremeev, I.V. Gonin, T.N. Khabiboulline, Y.M. Pischalnikov, O.V. Prokofiev, A.I. Sukhanov, J.C. Yun Fermilab, Batavia, Illinois, USA
	The PIP-II linac will include thirty-six B_G=0.61 and twenty-four B_G=0.92 650 MHz 5 cell elliptical SRF cavities. Each cavity will be equipped with a tuning system consisting of a double lever slow tuner for coarse frequency tuning and a piezoelectric actuator for fine frequency tuning. The same tuner will be used for both the B_G=0.61 and B_G=0.92 cavities. Results of testing the cavity-tuner system for the B_G=0.61 will be presented for the first time.
	Poster MOPA27 [0.782 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA27
About •	Received ※ 03 August 2022 — Revised ※ 10 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 04 October 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPA30	LCLS-II BCS Average Current Monitor	120
	N.M. Ludlow, T.L. Allison, J.P. Sikora, J.J. Welch SLAC, Menlo Park, California, USA
	LCLS-II is a 4th generation light source at the SLAC National Accelerator Laboratory. LCLS-II will accelerate a 30 µA electron beam with a 1 MHz bunch rate with a new superconducting Continuous Waveform (CW) RF accelerator. The Average Current Monitor (ACM) is part of the Beam Containment System (BCS) for the LCLS-II accelerator. The Beam Containment System is a safety system that provides paths to safely shut the accelerator beam off under a variety of conditions. The Average Current Monitor is a beam diagnostic within the BCS that is used to verify that the accelerator is producing the appropriate current level and to limit beam power to allowed values to protect the machine and beam dumps. The average beam current is obtained by measuring the power level induced by the beam in a low Q cavity. By knowing the Q, the beta, and the coupling of the cavity, the instantaneous charge can be calculated, then integrating the instantaneous charge over one millisecond will yield the average current. This paper will discuss progress in the checkout process of the ACM LLRF hardware leading to LCLS-II commissioning.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA30
About •	Received ※ 16 July 2022 — Revised ※ 05 August 2022 — Accepted ※ 24 August 2022 — Issue date ※ 06 October 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPA38	Accelerated Lifetime Test of the SRF Dressed Cavity/Tuner System for the LCLS II HE Project	136
	Y.M. Pischalnikov, T.T. Arkan, C. Contreras-Martinez, B.D. Hartsell, J.A. Kaluzny, Y.M. Orlov, R.V. Pilipenko, J.C. Yun Fermilab, Batavia, Illinois, USA W. Lahmadi Wahid Lahmadi, Williston, USA
	The off-frequency detune method is being considered for application in the LCLS-II-HE superconducting linac to produce multi-energy electron beams for supporting multiple undulator lines simultaneously. Design of the tuner has been changed to deliver roughly 3 times larger frequency tuning range. Working requirements for off-frequency operation (OFO) state that cavities be tuned at least twice a month. This specification requires the increase of the tuner longevity by 30 times compared with LCLS-II demands. Accelerated longevity tests of the LCLS-II HE dressed cavity with tuner were conducted at FNAL’s HTS. Detail analysis of wearing and impacts on performances of the tuner’s piezo and stepper motor actuators will be presented. Additionally, results of longevity testing of the dressed cavity bellow, when cooled down to 2 K and compressed by 2.6 mm for roughly 2000 cycles, will be presented.
	Poster MOPA38 [3.026 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA38
About •	Received ※ 29 July 2022 — Revised ※ 06 August 2022 — Accepted ※ 09 August 2022 — Issue date ※ 11 August 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPA42	Considerations Concerning the Use of HTS Conductor for Accelerator Dipoles with Inductions above 15 T	143
	M.A. Green LBNL, Berkeley, California, USA
	Funding: This work was supported by the office of Science, under US Department of Energy contract number DE-AC-02-05CH11231. The use of high temperature superconductors for accelerator dipole has been discussed for about twenty years and maybe a little more. Conductors that can potentially be used for accelerator magnets have been available for about fifteen years. These conductors are REBCO tape conductors, which can be wound into coils with no reaction after winding, and BISSCO cable conductors, which require reaction after winding and insulation after reaction in a process similar to Nb₃Sn cables. Both conductors are expensive and the process after reacting is expensive. Some unknown factors that remain: Will either conductor degrade in current carrying capacity with repeated cycling like Nb₃Sn cables do? The other two issues are problems for both types of HTS conductors and they are; 1) quench protection in the event of a normal region run-away and 2) dealing with the superconducting magnetization inherent with HTS cables and tapes. This paper will discuss the last two issues and maybe will provide a partial solution to these problems.
	Poster MOPA42 [1.498 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA42
About •	Received ※ 01 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 23 August 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPA45	Vacuum Electron Devices in the 88-Inch Cyclotron	154
	M. Kireeff Covo, J.Y. Benitez, P. Bloemhard, J.P. Garcia, B. Ninemire, L. Phair, D.S. Todd, D.Z. Xie LBNL, Berkeley, California, USA
	Funding: This work was supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under Contract No. DE-AC02-05CH11231 The 88-Inch Cyclotron at Lawrence Berkeley National Laboratory is a sector-focused cyclotron that has light- and heavy-ion capabilities and supports a local research program in Nuclear Science and is the home of the Berkeley Accelerator Space Effects Facility, which studies effects of radiation on microelectronics, optics, materials, and cells. The cyclotron utilizes several vacuum electron devices (VEDs) in different systems, mainly to convey plasma heating, high power RF generation, and high-voltage and current DC power generation. VEDs have been proven reliable, robust, and radiation resistant. They also have wide range, good response against transients, and stable operation with load mismatch during system tuning, instabilities, or breakdowns. The paper will describe applications of these devices in the 88-Inch Cyclotron
	Poster MOPA45 [1.434 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA45
About •	Received ※ 02 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 12 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPA59	Prediction of Gaseous Breakdown for Plasma Cleaning of RF Cavities	174
	S.A. Ahmed Ansys, Inc., Canonsburg, USA
	The quest for a high accelerating gradient in superconducting radio frequency cavity attracted scientists to adopt the plasma cleaning technology. Generating an efficient plasma inside a complex cavity structure for a desired frequency, gas types, and pressure for a given temperature is a challenge. The onset of discharge can be obtained from the well-known Paschen curve. Setting up an experiment is expensive and time-consuming, which may lead to a significant delay in the project. A high-fidelity computer simulation, modeling an arbitrary geometry and tracking the Paschen curve in a complex electromagnetic environment is therefore necessary. Ansys HFSS through its Finite Element Mesh (FEM) for the full-wave EM simulations combined with the electron impact ionization of gases enables the successful prediction of plasma breakdown for an arbitrary configuration for a wide frequency band and variety of gases. A comprehensive study will be demonstrated at the conference. The author like to thank Robert Chao for the valuable discussions and his efforts in developing this capability in the Ansys Electronics Desktop.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA59
About •	Received ※ 01 August 2022 — Revised ※ 03 August 2022 — Accepted ※ 06 August 2022 — Issue date ※ 19 August 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPA61	Modular Solid-State Switching and Arc Suppression for Vacuum Tube Bias Circuits	179
	E.L. Atkinson, T.J. Houlahan, B.E. Jurczyk, R.A. Stubbers Starfire Industries LLC, Champaign, USA
	In this work, we present operational and performance data for a solid-state switching circuit that delivers pulsed power at up to 12 kV and 100 A. This circuit, which is comprised of a series configuration of IGBT-based subcircuits, is suitable for driving the high-power vacuum-tube amplifiers that are typically used in RF accelerator systems. Each subcircuit can switch up to 3 kV, and the subcircuits can be stacked in series to extend the overall voltage capabilities of the switch. The circuit is designed to prevent overvoltaging any single transistor during switching transients or faults, regardless of the number of series subcircuits. Further, the circuit also includes the capability for rapid arc detection and suppression. Testing has shown effective switching at up to 100 A at 12 kV and for pulse repetition frequencies and durations in the range of 1-200 Hz and 10-50 µs, respectively. Additionally, the arc suppression circuitry has been shown to reliably limit arcs at 8-12 kV with a quench time of <1 µs and with a total energy of <0.2 J, minimizing the grid erosion in the vacuum-tube during an arc.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA61
About •	Received ※ 01 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 20 August 2022 — Issue date ※ 10 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPA62	High Quality Conformal Coatings on Accelerator Components via Novel Radial Magnetron with High-Power Impulse Magnetron Sputtering	182
	W.M. Huber, I. Haehnlein, T.J. Houlahan, B.E. Jurczyk, A.S. Morrice, R.A. Stubbers Starfire Industries LLC, Champaign, USA
	Funding: This material is based upon work supported by the U.S. Department of Energy under Award Numbers DE-SC0019784 and DE-SC0020481. In this work, we present two configurations of a novel radial magnetron design that are suitable for coating the complex inner surfaces of a variety of modern particle accelerator components. These devices have been used in conjunction with high-power impulse magnetron sputtering (HiPIMS) to deposit copper and niobium films onto the inner surfaces of bellows assemblies, waveguides, and SRF cavities. These films, with thicknesses of up to 3 µm and 40 µm for niobium and copper, respectively, have been shown to be conformal, adherent, and conductive. In the case of copper, the post-bake RRR values of the resulting films are well within the range specified for electroplating of the LCLS-II bellows and CEBAF waveguide assemblies. In addition to requiring no chemical processing beyond a detergent rinse and solvent degrease, this magnetron design exhibits over 80% target material utilization. Further, in the case of niobium, an enhancement in RRR over that of the bulk (target) material has been observed.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA62
About •	Received ※ 02 August 2022 — Revised ※ 05 August 2022 — Accepted ※ 09 August 2022 — Issue date ※ 21 August 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPA63	Multiphysics Simulation of the Thermal Response of a Nanofibrous Target in a High-Intensity Beam	185
	W.J. Asztalos IIT, Chicago, Illinois, USA S.K. Bidhar, F. Pellemoine Fermilab, Batavia, Illinois, USA P. Rath IIT Bhubaneswar, Jatni, India Y. Torun Illinois Institute of Technology, Chicago, Illlinois, USA
	Nanofibrous structures are of high interest to the fields of engineering and materials science, and investigation of their properties as well as discovery of novel applications for them both constitute lively areas of research. A very promising application of nanofiber mats lies in the field of accelerator technology: beam targets made from nanofiber mats offer a solution to the problem of advancing the "intensity frontier"–-the limit on the beam intensities that can be realized in fixed target experiments and neutrino production facilities. However, testing has shown that the survivability of these nanofiber targets depends strongly on their manufacturing parameters, such as the packing density of fibers. In this work, we will use multiphysics simulations to perform a thermal study on how nanofiber targets react to high intensity beams, so that the dependency of the targets’ lifetime on their construction parameters can be better understood.
	Poster MOPA63 [3.656 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA63
About •	Received ※ 14 July 2022 — Revised ※ 02 August 2022 — Accepted ※ 04 August 2022 — Issue date ※ 25 August 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPA67	Examining the Effects of Oxygen Doping on SRF Cavity Performance	196
	H. Hu, Y.K. Kim University of Chicago, Chicago, Illinois, USA D. Bafia Fermilab, Batavia, Illinois, USA
	Superconducting radiofrequency (SRF) cavities are resonators with extremely low surface resistance that enable accelerating cavities to have extremely high quality factors (Q₀). High (Q₀) decreases the capital required to keep accelerators cold by reducing power loss. The performance of SRF cavities is largely governed by the surface composition of the first 100 nm of the cavity surface. Impurities such as oxygen and nitrogen have been observed to yield high Q₀, but their precise roles are still being studied. Here, we compare the performance of cavities doped with nitrogen and oxygen in terms of fundamental material properties to understand how these impurities affect performance. This enables us to have further insight into the underlying mechanisms that enable these surface treatments to yield high Q₀ performance.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA67
About •	Received ※ 02 August 2022 — Accepted ※ 05 August 2022 — Issue date ※ 03 October 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPA83	Automation of Superconducting Cavity and Superconducting Magnet Operation for FRIB	239
	W. Chang, Y. Choi, X.-J. Du, W. Hartung, S.H. Kim, T. Konomi, S.R. Kunjir, H. Nguyen, J.T. Popielarski, K. Saito, T. Xu, S. Zhao FRIB, East Lansing, Michigan, USA
	The superconducting (SC) driver linac for the Facility for Rare Isotope Beams (FRIB) is a heavy-ion accelerator that accelerate ions to 200 MeV per nucleon. The linac has 46 cryomodules that contain 324 SC cavities and 69 SC solenoid packages. For linac operation with high availability and high reliability, automation is essential for such tasks as fast device turn-on/off, fast recovery from trips, and real-time monitoring of operational performance. We have implemented several automation algorithms, including one-button turn-on/off of SC cavities and SC magnets; automated degaussing of SC solenoids; mitigation of field emission-induced multipacting during recovery from cavity trips; and real-time monitoring of the cavity field level calibration. The design, development, and operating experience with automation will be presented.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA83
About •	Received ※ 02 August 2022 — Revised ※ 03 August 2022 — Accepted ※ 06 August 2022 — Issue date ※ 26 August 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPA84	Superconducting Cavity Commissioning for the FRIB Linac	242
	W. Chang, W. Hartung, S.H. Kim, T. Konomi, S.R. Kunjir, J.T. Popielarski, K. Saito, T. Xu, S. Zhao FRIB, East Lansing, Michigan, USA
	The superconducting driver linac for the Facility for Rare Isotope Beams (FRIB) is a heavy ion accelerator that has 46 cryomodules with 324 superconducting (SC) cavities that accelerate ions to 200 MeV per nucleon. Linac commissioning was done in multiple phases, in parallel with technical installation. Ion beam have now been accelerated to the design energy through the full linac; rare isotopes were first produced in December 2021; and the first user experiment was completed in May 2022. All cryomodules were successfully commissioned. Cryomodule commissioning included establishing the desired cavity fields, measuring field emission X-rays, optimizing the tuner control loops, measuring the cavity dynamic heat load, and confirming the low-level RF control (amplitude and phase stability). Results on cryomodule commissioning and cryomodule performance will be presented.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA84
About •	Received ※ 13 July 2022 — Revised ※ 02 August 2022 — Accepted ※ 13 August 2022 — Issue date ※ 05 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPA85	Design of a 185.7 MHz Superconducting RF Photoinjector Quarter-Wave Resonator for the LCLS-II-HE Low Emittance Injector	245
	S.H. Kim, W. Hartung, T. Konomi, S.J. Miller, M.S. Patil, J.T. Popielarski, K. Saito, T. Xu, T. Xu FRIB, East Lansing, Michigan, USA C. Adolphsen, L. Ge, F. Ji, J.W. Lewellen, L. Xiao SLAC, Menlo Park, California, USA M.P. Kelly, T.B. Petersen, P. Piot ANL, Lemont, Illinois, USA P. Piot Northern Illinois University, DeKalb, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy Contract DE-AC02-76SF00515. A 185.7 MHz superconducting quarter-wave resonator (QWR) was designed for the low emittance injector of the Linac Coherent Light Source high energy upgrade (LCLS-II-HE). The cavity was designed to minimize the risk of cathode efficiency degradation due to multipacting or field emission and to operate with a high RF electric field at the cathode for low electron-beam emittance. Cavity design features include: (1) shaping of the cavity wall to reduce the strength of the low-field coaxial multipacting barrier; (2) four ports for electropolishing and high-pressure water rinsing; and (3) a fundamental power coupler (FPC) port located away from the accelerating gap. The design is oriented toward minimizing the risk of particulate contamination and avoid harmful dipole components in the RF field. The ANL 162 MHz FPC design for PIP-II is being adapted for the gun cavity. We will present the RF design of the cavity integrated with the FPC.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA85
About •	Received ※ 03 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 30 August 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPA86	Conditioning of Low-Field Multipacting Barriers in Superconducting Quarter-Wave Resonators	249
	S.H. Kim, W. Chang, W. Hartung, J.T. Popielarski, T. Xu FRIB, East Lansing, Michigan, USA
	Funding: This is based upon work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661, the State of Michigan and Michigan State University. Multipacting (MP) barriers are typically observed at very low RF amplitude, at a field 2 to 3 orders of magnitude below the operating gradient, in low-frequency (<~100 MHz), quarter-wave resonators (QWRs). Such barriers may be troublesome, as RF conditioning with a fundamental power coupler (FPC) of typical coupling strength (external Q = 10⁶ to 10⁷) is generally difficult. For the FRIB \beta = 0.085 QWRs (80.5 MHz), the low barrier is observed at an accelerating gradient (E_acc) of ~10 kV/m; the operating E_acc is 5.6 MV/m. Theoretical and simulation studies suggested that the conditioning is difficult due to the relatively low RF power dissipated into multipacting rather than being a problem of the low barrier being stronger than other barriers. We developed a single-stub coaxial FPC matching element for external adjustment of the external Q by one order of magnitude. The matching element provided a significant reduction in the time to condition the low barrier. We will present theoretical and simulation studies of the low MP barrier and experimental results on MP conditioning with the single-stub FPC matching element.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA86
About •	Received ※ 03 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 21 August 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPA87	Design of the Cathode Stalk for the LCLS-II-HE Low Emittance Injector	253
	T. Konomi, W. Hartung, S.H. Kim, S.J. Miller, D.G. Morris, J.T. Popielarski, K. Saito, A. Taylor, T. Xu FRIB, East Lansing, Michigan, USA C. Adolphsen, J.W. Lewellen SLAC, Menlo Park, California, USA S. Gatzmaga, P. Murcek, R. Xiang HZDR, Dresden, Germany M.P. Kelly, T.B. Petersen ANL, Lemont, Illinois, USA
	Superconducting radio-frequency (SRF) electron guns are attractive for delivery of beams at a high bunch repetition rate with a high accelerating field. An SRF gun is the most suitable injector for the high-energy upgrade of the Linac Coherent Light Source (LCLS-II-HE), which will produce high-energy X-rays at high repetition rate. An SRF gun is being developed for LCLS-II-HE as a collaborative effort by FRIB, HZDR, ANL, and SLAC. The cavity operating frequency is 185.7 MHz, and the target accelerating field at the photocathode is 30 MV/m. The photocathode is replaceable. The cathode is held by a fixture (’cathode stalk’) that is designed for thermal isolation and particle-free cathode exchange. The stalk must allow for precise alignment of the cathode position, cryogenic or room-temperature cathode operating temperature, and DC bias to inhibit multipacting. We are planning a test of the stalk to confirm that the design meets the requirements for RF power dissipation and biasing. In this presentation, we will describe the cathode stalk design and RF/DC stalk test plan.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA87
About •	Received ※ 04 August 2022 — Revised ※ 11 August 2022 — Accepted ※ 18 August 2022 — Issue date ※ 11 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPA91	Plasma Processing of Superconducting Quarter-Wave Resonators Using a Higher-Order Mode	267
	W. Hartung, W. Chang, K. Elliott, S.H. Kim, T. Konomi, J.T. Popielarski, K. Saito, T. Xu FRIB, East Lansing, Michigan, USA
	The Facility for Rare Isotope Beams (FRIB) is a superconducting ion linac with acceleration provided by 104 quarter-wave resonators (QWRs) and 220 half-wave resonators (HWRs); FRIB user operations began in May 2022. Plasma cleaning is being developed as a method to mitigate possible future degradation of QWR or HWR performance: in-situ plasma cleaning represents an alternative to removal and disassembly of cryomodules for refurbishment of each cavity via repeat etching and rinsing. Initial measurements were done on a QWR and an HWR with room-temperature-matched input couplers to drive the plasma via the fundamental mode. Subsequent plasma cleaning tests were done on two additional FRIB QWRs using the fundamental power coupler (FPC) to drive the plasma. When using the FPC, a higher-order mode (HOM) at 5 times the accelerating mode frequency was used to drive the plasma. Use of the HOM allowed for less mismatch at the FPC and hence lower field in the coupler relative to the cavity. A neon-oxygen gas mixture was used for plasma generation. Before and after cold tests showed a significant reduction in field emission X-rays after plasma cleaning. Results will be presented.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA91
About •	Received ※ 12 August 2022 — Revised ※ 16 August 2022 — Accepted ※ 25 August 2022 — Issue date ※ 16 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPA02	Characterization of Octupole Elements for IOTA	351
	J.N. Wieland MSU, East Lansing, Michigan, USA J.D. Jarvis, A.L. Romanov, A. Valishev Fermilab, Batavia, Illinois, USA
	Funding: Work partially supported by the US Department of Energy, Office of Science, High Energy Physics under Cooperative Agreement award number DE-SC0018362 and Michigan State University. The Integrable Optics Test Accelerator (IOTA) is a research storage ring constructed and operated at Fermilab to demonstrate the advantages of nonlinear integrable lattices. One of the nonlinear lattice configurations with one integral of motion is based on a string of short octupoles. The results of the individual magnet’s characterizations, which were necessary to determine their multipole composition and magnetic centers, are presented. This information was used to select and align the best subset of octupoles for the IOTA run 4.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA02
About •	Received ※ 03 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 09 August 2022 — Issue date ※ 08 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPA11	Magnet System for a Compact Microtron Source	363
	S.A. Kahn, R.J. Abrams, M.A. Cummings, R.P. Johnson, G.M. Kazakevich Muons, Inc, Illinois, USA
	Funding: Work supported in part by U.S. D.O.E. SBIR grant DE-SC0013795. A microtron can be an effective intense electron source. It can use less RF power than a linac to produce a similar energy because the beam will pass through the RF cavity several times. To produce a high-quality low-emittance beam with a microtron requires a magnetic system with a field uniformity $δ B/B<0.001. Field quality for a compact microtron with fewer turns is more difficult to achieve. In this study we describe the magnet for a compact S-band microtron that will achieve the necessary field requirements. The shaping of the magnet poles and shimming of the magnet iron at the outer extent of the poles will be employed to provide field uniformity. The extraction of the beam will be discussed.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA11
About •	Received ※ 04 August 2022 — Revised ※ 14 August 2022 — Accepted ※ 06 September 2022 — Issue date ※ 08 October 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPA13	Affordable, Efficient Injection-Locked Magnetrons for Superconducting Cavities	366
	M. Popovic, M.A. Cummings, R.P. Johnson, S.A. Kahn, R.R. Lentz, M.L. Neubauer, T. Wynn Muons, Inc, Illinois, USA T. Blassick, J.K. Wessel Richardson Electronics Ltd, Lafox, Illinois, USA
	Funding: DE-SC0022586. Existing magnetrons that are typically used to study methods of control or lifetime improvements for SRF accelerators are built for much different applications such kitchen microwave ovens (1kW, 2.45 GHz) or industrial heating (100 kW, 915 MHz). In this project, Muons, Inc. will work with an industrial partner to develop fast and flexible manufacturing techniques to allow many ideas to be tested for construction variations that enable new phase and amplitude injection locking control methods, longer lifetime, and inexpensive refurbishing resulting in the lowest possible life-cycle costs. In Phase II magnetron sources will be tested on SRF cavities to accelerate an electron beam at JLab. A magnetron operating at 650 MHz will be constructed and tested with our novel patented subcritical voltage operation methods to drive an SRF cavity. The choice of 650 MHz is an optimal frequency for magnetron efficiency. The critical areas of magnetron manufacturing and design affecting life-cycle costs that will be modeled for improvement include: Q_ext, filaments, magnetic field, vane design, and novel control of outgassing.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA13
About •	Received ※ 05 August 2022 — Revised ※ 11 August 2022 — Accepted ※ 12 August 2022 — Issue date ※ 23 August 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPA15	Development of a CVD System for Next-Generation SRF Cavities	372
	G. Gaitan, P. Bishop, A.T. Holic, G. Kulina, J. Sears, Z. Sun Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA M. Liepe Cornell University, Ithaca, New York, USA B.W. Wendland University of Minnesota, Minnesota, USA
	Funding: This research is funded by the National Science Foundation under Grant No. PHY-1549132, the Center for Bright Beams. Next-generation, thin-film surfaces employing Nb₃Sn, NbN, NbTiN, and other compound superconductors are destined to allow reaching superior RF performance levels in SRF cavities. Optimized, advanced deposition processes are required to enable high-quality films of such materials on large and complex-shaped cavities. For this purpose, Cornell University is developing a remote plasma-enhanced chemical vapor deposition (CVD) system that facilitates coating on complicated geometries with a high deposition rate. This system is based on a high-temperature tube furnace with a clean vacuum and furnace loading system. The use of plasma alongside reacting precursors will significantly reduce the required processing temperature and promote precursor decomposition. The system can also be used for annealing cavities after the CVD process to improve the surface layer. The chlorine precursors have the potential to be corrosive to the equipment and pose specific safety concerns. A MATLAB GUI has been developed to control and monitor the CVD system at Cornell.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA15
About •	Received ※ 14 July 2022 — Revised ※ 08 August 2022 — Accepted ※ 09 August 2022 — Issue date ※ 22 August 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPA21	Hydrodynamic and Beam Dynamic Simulations of Ultra-Low Emittance Whole Beam Dumps in the Advanced Photon Source Storage Ring	390
	J.C. Dooling, M. Borland, A.M. Grannan, C.J. Graziani, Y. Lee, R.R. Lindberg, G. Navrotski ANL, Lemont, Illinois, USA N.M. Cook RadiaSoft LLC, Boulder, Colorado, USA D.W. Lee UCSC, Santa Cruz, California, USA
	Funding: Work supported by Accelerator Science and Technology LDRD Project 2021-0119 and the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. The Advanced Photon Source Upgrade will use a multi-bend achromatic lattice to reduce vertical and horizontal beam emittances by one- and two-orders of magnitude respectively; in addition operating current will double. The resulting electron beam will be capable of depositing more than 150 MGy on machine protection collimators creating high-energy-density conditions. Work is underway to couple the beam dynamics code Elegant with the particle-matter interaction program MARS and the magnetohydrodynamics code FLASH to model the effects of whole beam dumps on the collimators. Loss distributions from Elegant are input to MARS which provide dose maps to FLASH. We also examine the propagation of downstream shower components after the beam interacts with the collimator. Electrons and positrons are tracked to determine locations of beam loss. Beam dump experiments conducted in the APS storage-ring, generated dose levels as high as 30 MGy resulting in severe damage to the collimator surfaces with melting in the bulk. The deformed collimator surface may lead to beam deposition in unexpected locations. A fan-out kicker is planned to mitigate the effects of whole beam dumps on the collimators.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA21
About •	Received ※ 02 August 2022 — Revised ※ 10 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 10 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPA33	Magnetic Field Calculation of Superconducting Undulators for FEL Using Maxwell 3D	423
	Y. Shiroyanagi, Y. Ivanyushenkov, M. Kasa ANL, Lemont, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357. An ANL-SLAC collaboration is working on design of a planar superconducting undulator (SCU) demonstrator for a FEL. As a part of this project, a SCU magnet prototype is planned to be built and tested. A planar SCU magnet consisting of a 1.0-m-long segment is being designed. Although OPERA is a standard tool for magnetic field calculation, ANSYS Maxwell 3D can also be used for a large and complex geometry. An ANSYS calculated magnetic field was benchmarked with the measured field profile of existing SCUs. This paper presents calculations of magnetic field and field integrals of 0.5-m-long and 1.0-m-long planar SCUs with a new end correction scheme. Then, an external phase shifter is also incorporated into the model. A cross-talk between a phase shifter and SCU magnetic structures is also presented.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA33
About •	Received ※ 02 August 2022 — Revised ※ 03 August 2022 — Accepted ※ 05 August 2022 — Issue date ※ 25 August 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPA44	A Personal History of the Development of the LAMPF/LANSCE Accelerator	449
	J.M. Potter JP Accelerator Works, Los Alamos, New Mexico, USA
	The LAMPF/LANSCE accelerator has now been operational for 50 years. I arrived as a LASL employee in Group P11 in April 1964 at the beginning stages of its development. I participated in the development of the resonant coupling principle [1] and went on to develop tuning procedures for the 805-MHz coupled cavity linac (CCL) structures and the post-stabilized drift tube linac (DTL) [2]. The resonant coupling principle is now well established as the basis for rf linear accelerators worldwide. I will discuss the development and building of the accelerator from my viewpoint as a member of a large, dedicated team of physicists, engineers, technicians, and support personnel.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA44
About •	Received ※ 02 August 2022 — Revised ※ 04 August 2022 — Accepted ※ 05 August 2022 — Issue date ※ 05 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPA52	Initial Results of the 201.25 MHz Coaxial Window Test Stand	458
	T.W. Hall, J.T.M. Lyles, A. Poudel, A.S. Waghmare LANL, Los Alamos, New Mexico, USA
	We have recently commissioned an RF window test stand for the Drift Tube Linear Accelerator (DTL) portion of the Los Alamos Neutron Science Center (LANSCE). The window test stand consists of two RF windows that create a vacuum chamber which allows the windows to be tested to the peak power levels used in the DTL. Initial results clearly indicated multipactoring due to the increase of pressure at specific regions of peak forward power levels. Temperature measured at various azimuthal locations on both windows showed increased multipactor heating on the downstream window versus the upstream window. We present the effect of the titanium nitride coating that is presently applied to windows on both multipactor and window temperature. These results are discussed with respect to their impact on the LANSCE DTL performance.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA52
About •	Received ※ 25 July 2022 — Revised ※ 04 August 2022 — Accepted ※ 05 August 2022 — Issue date ※ 07 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPA59	RF System Upgrade for Low Energy DTL Cavity at LANSCE	478
	J.T.M. Lyles, R.E. Bratton, T.W. Hall, M. Sanchez Barrueta LANL, Los Alamos, New Mexico, USA
	Funding: Work supported by the United States Department of Energy, National Nuclear Security Agency, under contract 89233218CNA000001. The Los Alamos Neutron Science Center (LANSCE) 100-MeV Drift Tube Linac (DTL) uses four accelerating cavities. In May of 2021, a new RF amplifier system was commissioned to drive the first 4-MeV cavity. It had been powered for 30 years with a triode vacuum tube RF amplifier driven by a tetrode, along with four more vacuum tubes for anode high-voltage modulation. The new amplifier system uses one tetrode amplifier driven by a 20-kW solid state amplifier (SSA) to generate 400 kWp at 201.25 MHz. The tetrode amplifier is protected for reflected power from the DTL by a coaxial circulator. The new installation includes cRio controls and a fast protection and monitoring system capable of reacting to faults within 10 µs. A new digital low-level RF (LLRF) system has been installed that integrates I/Q signal processing, PI feedback, and feedforward controls for beam loading compensation. Issues with LLRF stability were initially encountered due to interaction from thermal-related RF phase changes. After these issues were solved, the final outcome has been a reliable new RF system to complete the overall upgrade of the LANSCE DTL RF power plant.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA59
About •	Received ※ 03 August 2022 — Revised ※ 04 August 2022 — Accepted ※ 06 August 2022 — Issue date ※ 12 August 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPA64	Analysis of Resonant Converter Topology for High-Voltage Modulators	486
	M. Sanchez Barrueta, J.T.M. Lyles, M.D.M. Morris LANL, Los Alamos, New Mexico, USA
	Funding: Work Supported by the United States Department of Energy, National Nuclear Security Agency, under contract DE-AC52-06NA25396 At the Los Alamos Neutron Science Center (LANSCE), we are considering various topologies to replace obsolete charging supplies and capacitor banks that provide high-voltage direct-current (DC) power to the 44, 805-MHz klystron modulators that drive the LANSCE Coupled Cavity Linac (CCL). Among the possible replacement topologies is the High Voltage Converter Modulator (HVCM), originally designed at LANSCE for use at the Spallation Neutron Source (SNS), to be used as a pulsed high-voltage power supply for klystron-based RF transmitters. The HVCM topology uses high frequency transformers with resonant LC networks for efficient energy conversion and a frequency dependent gain, which permits the use of frequency modulation as a control variable to afford pulse flattening and excellent regulation as demonstrated at SNS. A mathematical analysis is presented that links the converter resonant tank components to the frequency dependent output behavior of the converter modulator. LA-UR-22-25179
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA64
About •	Received ※ 03 August 2022 — Revised ※ 10 August 2022 — Accepted ※ 12 August 2022 — Issue date ※ 22 August 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPA69	Improving Cavity Phase Measurements at Los Alamos Neutron Science Center	493
	P. Van Rooy, A.T. Archuleta, L.J. Castellano, S. Kwon, M.S. Prokop, P.A. Torrez LANL, Los Alamos, New Mexico, USA
	Control stability of the phase and amplitude in the cavity is a significant contributor to beam performance. The ability to measure phase and amplitude of pulsed RF systems at accuracies of ± 0.1 degrees and ± 0.1 percent required for our systems is difficult, and custom-designed circuitry is required. The digital low-level RF upgrade at the Los Alamos Neutron Science Center is continuing to progress with improved cavity phase measurements. The previous generation of the cavity phase and amplitude measurement system has a phase ambiguity, which requires repeated calibrations to ascertain the correct phase direction. The new phase measurement system removes the ambiguity and the need for field calibration while improving the range and precision of the cavity phase measurements. In addition, the new digital low-level RF systems is designed to upgrade the legacy system without significant mechanical, electrical, or cabling changes. Performance data for the new phase measurement system is presented.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA69
About •	Received ※ 02 August 2022 — Revised ※ 11 August 2022 — Accepted ※ 21 August 2022 — Issue date ※ 08 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPA73	Design and Low Power Test of an Electron Bunching Enhancer Using Electrostatic Potential Depression	499
	H. Xu, B.E. Carlsten, Q.R. Marksteiner LANL, Los Alamos, New Mexico, USA B.L. Beaudoin, T.W. Koeth, A. Ting UMD, College Park, Maryland, USA
	Funding: This project was supported by the U.S. Department of Energy Office of Science through the Accelerator Stewardship Program. We present our experimental design and low power test results of a structure for the proof-of-principle demonstration of fast increase of the first harmonic current content in a bunched electron beam, using the technique of electrostatic potential depression (EPD). A primarily bunched electron beam from an inductive output tube (IOT) at 710 MHz first enters an idler cavity, where the longitudinal slope of the beam energy distribution is reversed. The beam then transits through an EPD section implemented by a short beam pipe with a negative high voltage bias, inside which the rate of increase of the first harmonic current is significantly enhanced. An output cavity measures the harmonic current developed inside the beam downstream of the EPD section. Low power test results of the idler and the output cavities agree with the theoretical design.
	Poster TUPA73 [1.307 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA73
About •	Received ※ 29 July 2022 — Accepted ※ 03 August 2022 — Issue date ※ 09 August 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEXE1	Accelerator Science and Technology via Inventive Principles of TRIZ
	A. Seryi JLab, Newport News, Virginia, USA
	A swift overview of modern areas of accelerator physics and technology presented via and connected through inventive principles of TRIZ, the industrial methodology of inventiveness. A wide range of topics, such as synchrotron radiation, electron cooling, plasma acceleration, are introduced via easy-to-follow back-of-the-envelope derivations. These are connected via canonical yet adjusted for science TRIZ inventive principles and laws, illustrated by numerous inventions such as fiber lasers, tune jumps, inverted guns, and others. This short tutorial introduces a new approach which amalgamates science and industrial inventiveness, enhances creativity, and boosts innovations towards developing the next generations of accelerators and their applications.
	Slides WEXE1 [16.003 MB]
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEZD1	ARDAP’s Perspective on Accelerator Technology R&D in the U.S.	592
	B.E. Carlsten, E.R. Colby, R.A. Marsh, M. White ARDAP, Washington, USA
	DOE operates several particle accelerator facilities and is planning several new forward-leaning accelerator facilities over the next decade or two. These new facilities will focus on discovery science research and fulfilling other core DOE missions. Near and mid-term examples include PIP-II and FACET-II (for High Energy Physics); LCLS-II, SNS-PPU, APS-U, and ALS-U (for Basic Energy Sciences); FRIB (for Nuclear Physics); NSTX-U and MPEX (for Fusion Energy Sciences); and Scorpius (for NNSA). Longer-term examples may include future colliders, the SNS-STS, LCLS-II HE, and EIC. In addition to domestic facilities, DOE’s Office of Science (SC) also contributes to several international efforts. Together, these new facilities constitute a multibillion-dollar construction and operations investment. To be successful, they will require advances in state-of-the-art accelerator technologies. They will also require the National Laboratories to procure a variety of accelerator components. This paper summarizes how DOE is working to address these upcoming R&D and accelerator component production needs through its new office of Accelerator R&D and Production (ARDAP).
	Slides WEZD1 [2.310 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEZD1
About •	Received ※ 05 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 19 August 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEZD2	Solid State Active Reset Induction Technology to Accelerate kA Electron Beam
	J. Ellsworth LLNL, Livermore, USA
	We will discuss Solid State Active reset technology and how it can be applied to kA electron beams.
	Slides WEZD2 [2.871 MB]
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEZD3	Magnetron R&D Progress for High Efficiency CW RF Sources of Industrial Accelerators	597
	H. Wang, K. Jordan, R.M. Nelson, S.A. Overstreet, R.A. Rimmer JLab, Newport News, Virginia, USA J.N. Blum VCU, Richmond, Virginia, USA B.R.L. Coriton, C.P. Moeller, K.A. Thackston GA, San Diego, California, USA J.L. Vega The College of William and Mary, Williamsburg, Virginia, USA G. Ziemyte UKY, Kentucky, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177, and DOE OS/HEP Accelerator Stewardship award 2019-2022. After the demonstration of using high efficiency magnetron power to combine and aim to drive a radio frequency accelerator at 2450MHz in CW mode [1], we have used trim coils adding to a water-cooled magnetron and three amplitude modulation methods in an open-loop control to further suppress the 120Hz side-band noise to -46.7dBc level. We have also successfully demonstrated the phase-locking to an industrial grade cooking magnetron transmitter at 915MHz with a 75kW CW power delivered to a water load by using a -26.6dBc injection signal. The sideband noise at 360Hz from the 3-Phase SCRs DC power supply can be reduced to -16.2dBc level. Their power combing scheme and higher power application to industrial accelerators are foreseeing. [1] H. Wang, et al, Magnetron R&D for High Efficiency CW RF Sources for Industrial Accelerators, TUPAB348, 12th Int. Particle Acc. Conf. IPAC2021, Campinas, SP, Brazil.
	Slides WEZD3 [3.074 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEZD3
About •	Received ※ 18 July 2022 — Revised ※ 25 July 2022 — Accepted ※ 08 August 2022 — Issue date ※ 11 August 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEZD4	Using Off-Axis Undulator Radiation as a Longitudinal Electron-Beam Diagnostic
	Q.R. Marksteiner, H.L. Andrews, J.E. Coleman, W.P. Romero, N.A. Yampolsky, M.R.A. Zuboraj LANL, Los Alamos, New Mexico, USA S.K. Barber, R.D. Ryne, J. van Tilborg LBNL, Berkeley, USA C. Emma SLAC, Menlo Park, California, USA B. Ostler University of Chicago, Chicago, Illinois, USA
	Funding: This project was supported by funding from the Los Alamos National Laboratory Laboratory Research and Development program. A novel diagnostic has been developed that uses off-axis undulator radiation to characterize the longitudinal bunch profile of an electron beam. The diagnostic uses a small, ~0.1-m long undulator with mirrors that focus the undulator radiation onto an array of pyrometers. The mirrors both focus the radiation onto the pyrometer and remove the chirping effect that comes from the finite length of the undulator. Numerical and analytical models have been developed to calculate the radiation for a given bunch length, and a phase retrieval algorithm has been developed to extract the bunch profile from measured data. The diagnostic has been installed at the BELLA laser-plasma wakefield accelerator, and will be used to characterize the bunch length there. The concept and relevant results will be presented.
	Slides WEZD4 [3.577 MB]
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEZD5	Micro-Electromechanical Systems Based Multi-Beam Ion Accelerators
	Q. Ji, A. Amsellem, A. Persaud, Z. Qin, T. Schenkel, P.A. Seidl, N. Valverde LBNL, Berkeley, California, USA K. Afridi, V. Gund, Y. Hou, A. Lal, D. Ni Cornell University, Ithaca, New York, USA S.M. Lund FRIB, East Lansing, Michigan, USA
	Funding: This work was funded by ARPA-E. Work at LBNL was conducted under DOE Contract DE-AC0205CH11231. Device fabrication at the Cornell Nano Fabrication facility is supported by NSF Grant No. ECCS-1542081. We report on the development of multi-beam radio frequency (RF) linear ion accelerators that are formed from stacks of low-cost printed circuit boards. An array of 112 beamlets is formed using MEMS techniques in 4" wafers. The peak argon ion current accelerated in the 112-beamlet column to date is 0.5 mA [1]. We have accelerated ions in stacks of 32 wafers to an energy of 100 keV. The measured energy gain in each RF gap reached 6.5 keV on average, resulting in an effective acceleration gradient of 0.4 MV/m. We will describe how this approach to multi-beam RF ion acceleration can scale to high beam power for applications in material processing and nuclear materials development. [1] Qing Ji, et al., "Beam power scale-up in micro-electromechanical systems based multi-beam ion accelerators", Rev. Sci. Instr. 92, 103301 (2021); https://doi.org/10.1063/5.0058175
	Slides WEZD5 [4.575 MB]
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEZD6	Manufacturing the Harmonic Kicker Cavity Prototype for the Electron-Ion Collider	601
	S.A. Overstreet, M.W. Bruker, G.A. Grose, J. Guo, J. Henry, G.-T. Park, R.A. Rimmer, H. Wang, R.S. Williams JLab, Newport News, Virginia, USA
	Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177 High-bunch-frequency beam-separation schemes, such as the injection scheme proposed for the Rapid Cycling Synchrotron at the Electron-Ion Collider, demand rise and fall times an order of magnitude below what can realistically be accomplished with a stripline kicker. Nanosecond-time-scale kick waveforms can instead be obtained by Fourier synthesis in a harmonically resonant quarter-wave radio-frequency cavity which is optimized for high shunt impedance. Originally developed for the Jefferson Lab Electron-Ion Collider (JLEIC) Circulator Cooler Ring, a hypothetical 11-pass ring driven by an energy-recovery linac at Jefferson Lab, our high-power prototype of such a harmonic kicker cavity, which operates at five modes at the same time, will demonstrate the viability of this concept with a beam test at Jefferson Lab. As the geometry of the cavity, tight mechanical tolerances, and number of ports complicate the design and manufacturing process, special care must be given to the order of the manufacturing steps. We present our experiences with the manufacturability of the present design, lessons learned, and first RF test results from the prototype.
	Slides WEZD6 [12.312 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEZD6
About •	Received ※ 04 August 2022 — Revised ※ 05 August 2022 — Accepted ※ 18 August 2022 — Issue date ※ 31 August 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPA12	Operational Experience of the New Booster Cryomodule at the Upgraded Injector Test Facility	640
	M.W. Bruker, R. Bachimanchi, J.M. Grames, M.D. McCaughan, J. Musson, P.D. Owen, T.E. Plawski, M. Poelker, T. Powers, H. Wang, Y.W. Wang JLab, Newport News, Virginia, USA
	Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177. Since the early 1990s, the injector of the CEBAF accelerator at Jefferson Lab has relied on a normal-conducting RF graded-beta capture section to boost the kinetic energy of the electron beam from 100 / 130 keV to 600 keV for subsequent acceleration using a cryomodule housing two superconducting 5-cell cavities similar to those used throughout the accelerator. To simplify the injector design and improve the beam quality, the normal-conducting RF capture section and the cryomodule will be replaced with a new single booster cryomodule employing a superconducting, β = 0.6, 2-cell-cavity capture section and a single, β = 0.97, 7-cell cavity. The Upgraded Injector Test Facility at Jefferson Lab is currently hosting the new cryomodule to evaluate its performance with beam before installation at CEBAF. While demonstrating satisfactory performance of the booster and good agreement with simulations, our beam test results also speak to limitations of accelerator operations in a noisy, thermally unregulated environment.
	Poster WEPA12 [3.726 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA12
About •	Received ※ 03 August 2022 — Revised ※ 07 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 06 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPA16	A 500 kV Inverted Geometry Feedthrough for a High Voltage DC Electron Gun	651
	C. Hernandez-Garcia, D.B. Bullard, J.M. Grames, G.G. Palacios Serrano, M. Poelker JLab, Newport News, Virginia, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177 and Office of Science Funding Opportunity LAB 20-2310 award PAMS-254442. The Continuous Electron Beam Accelerator Facility injector at Jefferson Lab (JLab) utilizes an inverted-geometry ceramic insulator photogun operating at 130 kV direct current to generate spin-polarized electron beams for high-energy nuclear physics experiments. A second photogun delivers 180 keV beam for commissioning a SRF booster in a testbed accelerator, and a larger version delivers 300 keV magnetized beam in a test stand beam line. This contribution reports on the development of an unprecedented inverted-insulator with cable connector for reliably applying 500 kV DC to a future polarized beam photogun, to be designed for operating at 350 kV without field emission. Such a photogun design could then be used for generating a polarized electron beam to drive a spin-polarized positron source as a demonstrator for high energy nuclear physics at JLab. There are no commercial cable connectors that fit the large inverted insulators required for that voltage range. Our proposed concept is based on a modified epoxy receptacle with intervening SF6 layer and a test electrode in a vacuum vessel.
	Poster WEPA16 [6.217 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA16
About •	Received ※ 03 August 2022 — Revised ※ 05 August 2022 — Accepted ※ 07 August 2022 — Issue date ※ 09 October 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPA19	HE Production Update at JLab - Introducing an Enhanced Nitrogen Purge for Clean String Assembly	659
	P.D. Owen JLab, Newport News, Virginia, USA
	A major limitation to cryomodule performance is field emission caused by particulates within the superconducting cavities. To reduce contamination of the inner surfaces during assembly in a cleanroom, the whole string can be connected to a purge system, which maintains a constant overpressure of dry, clean nitrogen gas. Following successes of similar systems at XFEL and Fermilab, Jefferson Lab followed this example for the production of LCLS-II HE cryomodules. Implementing this system required new procedures, infrastructure, and hardware, as well as significant testing of the system before production began. This paper will summarize the implemented controls and procedures, including lessons learned from Fermilab, as well as the results of mock-up tests. Based on the latter, the system was used to assemble the first article string in April 2022, and was also used during a rework required due to issues with cold FPC ceramics two months later. The benefits of using a purge system with regards to procedure, time savings, and added flexibility for potential rework have already proven to provide a significant improvement for the production of LCLS-II-HE cryomodules at Jefferson Lab.
	Poster WEPA19 [1.538 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA19
About •	Received ※ 02 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 21 August 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPA26	197 MHz Waveguide Loaded Crabbing Cavity Design for the Electron-Ion Collider	679
	S.U. De Silva, J.R. Delayen ODU, Norfolk, Virginia, USA J. Guo, R.A. Rimmer JLab, Newport News, Virginia, USA Z. Li SLAC, Menlo Park, California, USA B.P. Xiao BNL, Upton, New York, USA
	The Electron-Ion Collider will require crabbing systems at both hadron and electron storage rings in order to reach the desired luminosity goal. The 197 MHz crab cavity system is one of the critical rf systems of the col-lider. The crab cavity, based on the rf-dipole design, ex-plores the option of waveguide load damping to suppress the higher order modes and meet the tight impedance specifications. The cavity is designed with compact dog-bone waveguides with transitions to rectangular wave-guides and waveguide loads. This paper presents the compact 197 MHz crab cavity design with waveguide damping and other ancillaries.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA26
About •	Received ※ 08 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 06 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPA27	Effect of Duration of 120 °C Baking on the Performance of Superconducting Radio Frequency Niobium Cavities	683
	B.D. Khanal ODU, Norfolk, Virginia, USA P. Dhakal JLab, Newport News, Virginia, USA
	Over the last decade much attention was given in increasing the quality factor of superconducting radio frequency (SRF) cavities by impurity doping. Prior to the era of doping, the final cavity processing technique to achieve the high accelerating gradient includes the "in situ" low temperature baking of SRF cavities at temperature ~ 120°C for several hours. Here, we present the results of a series of measurements on 1.3 GHz TESLA shape single-cell cavities with successive low temperature baking at 120°C up to 96 hours. The experimental data were analyzed with available theory of superconductivity to elucidate the effect of the duration of low temperature baking on the superconducting properties of cavity materials as well as the RF performance. In addition, the RF loss related to the trapping of residual magnetic field refereed as flux trapping sensitivity was measured with respect to the duration of 120°C bake.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA27
About •	Received ※ 01 August 2022 — Revised ※ 07 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 19 August 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPA30	Nb₃Sn Coating of a 2.6 GHz SRF Cavity by Sputter Deposition Technique	691
	M.S. Shakel, W. Cao, H. Elsayed-Ali, Md.N. Sayeed ODU, Norfolk, Virginia, USA G.V. Eremeev Fermilab, Batavia, Illinois, USA U. Pudasaini, A-M. Valente-Feliciano JLab, Newport News, Virginia, USA
	Funding: Supported by DOE, Office of Accelerator R&D and Production, Contact No. DE-SC0022284, with partial support by DOE, Office of Nuclear Physics DE-AC05-06OR23177, Early Career Award to G. Eremeev. Nb₃Sn is of interest as a coating for SRF cavities due to its higher transition temperature Tc ~18.3 K and superheating field Hsh ~400 mT, both are twice that of Nb. Nb₃Sn coated cavities can achieve high-quality factors at 4 K and can replace the bulk Nb cavities operated at 2 K. A cylindrical magnetron sputtering system was built, commissioned, and used to deposit Nb₃Sn on the inner surface of a 2.6 GHz single-cell Nb cavity. With two identical cylindrical magnetrons, this system can coat a cavity with high symmetry and uniform thickness. Using Nb-Sn multilayer sequential sputtering followed by annealing at 950°C for 3 hours, polycrystalline Nb₃Sn films were first deposited at the equivalent positions of the cavity’s beam tubes and equator. The film’s composition, crystal structure, and morphology were characterized by energy dispersive spectroscopy, X-ray diffraction, and atomic force microscopy. The Tc of the films was measured by the four-point probe method and was 17.61 to 17.76 K. Based on these studies, ~1.2 micron thick Nb₃Sn was deposited inside a 2.6 GHz Nb cavity. We will discuss first results from samples and cavity coatings, and the status of the coating system.
	Poster WEPA30 [1.769 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA30
About •	Received ※ 03 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 22 August 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPA31	Lower Temperature Annealing of Vapor Diffused Nb₃Sn for Accelerator Cavities	695
	J.K. Tiskumara, J.R. Delayen ODU, Norfolk, Virginia, USA G.V. Eremeev Fermilab, Batavia, Illinois, USA U. Pudasaini JLab, Newport News, Virginia, USA
	Nb₃Sn is a next-generation superconducting material for the accelerator cavities with higher critical temperature and superheating field, both twice compared to Nb. It promises superior performance and higher operating temperature than Nb, resulting in significant cost reduction. So far, the Sn vapor diffusion method is the most preferred and successful technique to coat niobium cavities with Nb₃Sn. Although several post-coating techniques (chemical, electrochemical, mechanical) have been explored to improve the surface quality of the coated surface, an effective process has yet to be found. Since there are only a few studies on the post-coating heat treatment at lower temperatures, we annealed Nb₃Sn-coated samples at 800 C - 1000 C to study the effect of heat treatments on surface properties, primarily aimed at removing surface Sn residues. This paper discusses the systematic surface analysis of coated samples after annealing at temperatures between 850 C and 950 C.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA31
About •	Received ※ 02 August 2022 — Revised ※ 05 August 2022 — Accepted ※ 07 August 2022 — Issue date ※ 02 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPA32	Spallation Neutron Source Cryogenic Moderator System Helium Gas Analysis System	699
	B. DeGraff, L. Pinion ORNL RAD, Oak Ridge, Tennessee, USA R. Armstrong, J. Denison, M.P. Howell, S.-H. Kim, D. Montierth ORNL, Oak Ridge, Tennessee, USA M.D. Williamson LBNL, Berkeley, California, USA
	Funding: This work was supported by SNS through UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE. The Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL) operates the Cryogenic Moderator System (CMS). The CMS comprises a 20-K helium refrigerator and three helium to hydrogen heat exchangers in support of hydrogen cooled spallation moderation vessels. This system uses vessels filled with activated carbon as the final major component to remove oil vapor from the compressed helium in the cryogenic cold box. SNS uses a LINDE multi-component gas analyzer to detect the presence of contaminants in the warm helium flow upstream of the cold box including aerosolized oil vapor. The design challenges of installing and operating this analyzer on the CMS system due to normal system operating pressures will be discussed. The design, fabrication, installation, commissioning, and initial results of this system operation will be presented. Future upgrades to the analyzer system will also be discussed.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA32
About •	Received ※ 06 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 05 October 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPA33	Laser Stripping for 1.3 GeV H⁻ Beam at the SNS	702
	T.V. Gorlov, A.V. Aleksandrov, S.M. Cousineau, Y. Liu, A.R. Oguz ORNL, Oak Ridge, Tennessee, USA M.J. Kay UTK, Knoxville, Tennessee, USA P.K. Saha JAEA/J-PARC, Tokai-mura, Japan
	Funding: This work has been authored by UT-Battelle, LLC, under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. A realistic full duty factor laser stripping charge exchange injection scheme for future 1.3 GeV beam at the SNS is considered. Different schemes of laser stripping involving combinations of photoexcitation, photoionization and magnetic field stripping are calculated. The laser power and magnetic field strength needed for different approaches are estimated and compared. The most practical scheme of laser stripping is selected for development.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA33
About •	Received ※ 29 July 2022 — Revised ※ 05 August 2022 — Accepted ※ 09 August 2022 — Issue date ※ 23 August 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPA37	Benchmarking and Exploring Parameter Space of the 2-Phase Bubble Tracking Model for Liquid Mercury Target Simulation	711
	L. Lin, M.I. Radaideh, H. Tran, D.E. Winder ORNL, Oak Ridge, Tennessee, USA
	Funding: This project was funded by the U.S. DOE under grant DE-SC0009915. High intensity proton pulses strike the Spallation Neutron Source (SNS)’s mercury target to provide bright neutron beams. These strikes deposit extensive energy into the mercury and its steel vessel. Prediction of the resultant loading on the target is difficult when helium gas is intentionally injected into the mercury to reduce the loading and to mitigate the pitting damage on the vessel. A 2-phase material model that incorporates the Rayleigh-Plesset (R-P) model is expected to address this complex multi-physics dynamics problem by including the bubble dynamics in the liquid mercury. We present a study comparing the measured target strains in the SNS target station with the simulation results of the solid mechanics simulation framework. We investigate a wide range of various physical model parameters, including the number of bubble families, bubble size distribution, viscosity, surface tension, etc. to understand their impact on simulation accuracy. Our initial findings reveal that using 8-10 bubble families in the model renders a simulation strain envelope that covers the experimental ones. Further optimization studies are planned to predict the strain response more accurately.
	Poster WEPA37 [1.985 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA37
About •	Received ※ 27 July 2022 — Revised ※ 08 August 2022 — Accepted ※ 12 August 2022 — Issue date ※ 01 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPA48	Electromagnetic Design of a Compact RF Chopper for Heavy-Ion Beam Separation at FRIB	738
	A.C. Araujo Martinez, R.B. Agustsson, Y.C. Chen, S.V. Kutsaev RadiaBeam, Santa Monica, California, USA A.S. Plastun, X. Rao FRIB, East Lansing, Michigan, USA
	Funding: This work was supported by the U.S. Department of Energy, Office of High Energy Physics, under SBIR grant DE- SC0020671. Rare isotope beams are produced at FRIB via fragmentation of a primary heavy ion beam in a thin target. The isotope beam of interest is contaminated with other fragments, which must be filtered out to ensure the delivery of rare isotopes with desired rates and purities. One of the stages of fragment separation uses an RF deflecting cavity to provide time-of-flight separation. However, to avoid neighboring bunches overlapping with each other and with the contaminants, it is necessary to increase the inter-bunch distance by a factor of four, corresponding to a 20.125 MHz rate. To solve this problem, we have developed an RF chopper system for the 500 keV/u primary heavy-ion beams. The system consists of a deflecting quarter wave resonator (QWR) cavity operating at 60.375 MHz, two dipole steering magnets, and a beam dump. In this paper, we present and discuss the optimization of the electromagnetic design of the QWR cavity and magnets, as well as some aspects, related to beam dynamics and conceptual engineering design.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA48
About •	Received ※ 02 August 2022 — Revised ※ 05 August 2022 — Accepted ※ 06 August 2022 — Issue date ※ 08 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPA49	Ferrite-Free Circulator for Precise Measurements of SRF Cavities with High Q-Factor	742
	A.I. Pronikov, A.Yu. Smirnov RadiaBeam, Santa Monica, California, USA A.A. Krasnok Florida International University, Miami, Florida, USA S.N. Romanenko Zaporizhzhya National Technical University, Zaporizhzhya, Ukraine V.P. Yakovlev Fermilab, Batavia, Illinois, USA
	Funding: This work was supported by the US Department of Energy, Offices of High Energy and Nuclear Physics, awards DE-SC0020926 and DE-SC0022439. In this work, we suggest and investigate new magnetless circulators based on three resonators connected in a loop and parametrically modulated in time with mutual phase lag. The first design consists of three Fano resonators with a spectrally asymmetric response, in contrast to schemes based on the Lorentz resonators explored thus far. The second design includes three Fano-Lorentz resonators, i.e., it also possesses spatial asymmetry. We demonstrate that the asymmetric approach provides strong and reversible isolation for the practically feasible modulation amplitude and rate. The results of our work are promising for precise measurements of superconducting radio frequency cavities with high Q-factor.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA49
About •	Received ※ 04 August 2022 — Revised ※ 07 August 2022 — Accepted ※ 09 August 2022 — Issue date ※ 13 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPA50	Initial Development of a High-Voltage Pulse Generator for a Short-Pulse Kicker	745
	J. Prager, K.E. Miller, K. Muggli, C. Schmidt, H. Yeager EHT, Seattle, Washington, USA
	Funding: This work was funded by a DOE SBIR (DE-SC0021470). The future Electron Ion Collider, to be located at Brookhaven National Laboratory (BNL), will require a new short-pulse stripline kicker for the 150 MeV energy recovery LINAC. The pulse generator must produce ±50 kV pulses with widths less than 38 ns into a 50° kicker load and with low jitter. The power system must be highly reliable and robust to potential faults. Eagle Harbor Technologies (EHT), Inc. is leveraging our previous experience developing inductive adders to produce a high-voltage pulse generator that can meet the needs of the BNL kickers. In this program, EHT designed a single inductive adder stage and demonstrated the challenging pulse characteristics including fast rise and fall times, low jitter, and flattop stability while operating at the full current (1 kA). EHT will present the development status and output waveforms.
	Poster WEPA50 [1.118 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA50
About •	Received ※ 01 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 12 August 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPA52	Demonstration of Twice-Reduced Lorentz-Force Detuning in SRF Cavity by Copper Cold Spraying	749
	R.A. Kostin, C.-J. Jing, A. Kanareykin Euclid TechLabs, Solon, Ohio, USA G. Ciovati JLab, Newport News, Virginia, USA
	Funding: The project is funded by DOE SBIR # DE-SC0019589 Superconducting RF (SRF) cavities usually are made from thin-walled high RRR Niobium and are susceptible to Lorentz Force Detuning (LFD) ’ cavity deformation phenomena by RF fields. In this paper, we present high gradient cryogenic results of an SRF cavity with two times reduced LFD achieved by copper cold spray reinforcement without sacrificing cavity flexibility for tuning. Finite-element model was developed first to find the best geometry for LFD reduction, which incorporated coupled RF, structural and thermal modules, and is also presented.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA52
About •	Received ※ 27 July 2022 — Revised ※ 03 August 2022 — Accepted ※ 09 August 2022 — Issue date ※ 16 August 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPA53	An Open Radiofrequency Accelerating Structure	753
	S.V. Kuzikov Euclid TechLabs, Solon, Ohio, USA
	We report an open multi-cell accelerating structure. Being integrated with a set of open-end waveguides, this structure can suppress high-order modes (HOMs). All the accelerating cells are connected at the side to rectangular cross-section waveguides which strongly coupled with free space or absorbers. Due to the anti-phased contribution of the cell pairs, the operating mode does not leak out, and has as high-quality factor as for a closed accelerating structure. However, the compensation does not occur for spurious high-order modes. This operating principle also allows for strong coupling between the cells of the structure, which is why high homogeneity of the accelerating fields can be provided along the structure. We discuss the obtained simulation results and possible applications. Its include a normal conducting high-shunt impedance accelerator, a tunable photoinjector’s RF gun, and a high-current, high-selective SRF accelerators.
	Poster WEPA53 [1.817 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA53
About •	Received ※ 01 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 12 August 2022 — Issue date ※ 16 August 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPA55	Applications of Machine Automation with Robotics and Computer Vision in Cleanroom Assemblies	756
	A. Liu, J.R. Callahan, E. Gomez, S.M. Milller, W. Si Euclid TechLabs, Solon, Ohio, USA
	Funding: This work is supported by the US DOE SBIR program under contract number DE-SC0021736. Modern linear particle accelerators use superconducting radio frequency (SRF) cavities for achieving extremely high-quality factors (Q) and higher beam stability. The assembly process of the system, although with a much more stringent cleanness requirement, is very similar to the ultrahigh vacuum (UHV) system operation procedure. Humans, who are conventionally the operators in this procedure, can only avoid contaminating the system by wearing proper sterile personal protection equipment to avoid direct skin contact with the systems, or dropping particulates. However, humans unavoidably make unintentional mistakes that can contaminate the environment: cross contamination of the coverall suits during wearing, slippage of masks or goggles, damaged gloves, and so forth. Besides, humans are limited when operating heavy weights, which may lead to incorrect procedures, or even worse, injury. In this paper, we present our recent work on a viable and cost-effective machine automation system composed of a robotic arm and a computer vision system for the assembly process in a cleanroom environment, for example for SRF string assemblies, and more.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA55
About •	Received ※ 30 July 2022 — Revised ※ 04 August 2022 — Accepted ※ 06 August 2022 — Issue date ※ 12 August 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPA56	Encapsulation of Photocathodes Using High Power Pulsed RF Sputtering of hBN	760
	A. Liu, J.R. Callahan, S. Poddar Euclid TechLabs, Solon, Ohio, USA J.P. Biswas, M. Gaowei BNL, Upton, New York, USA
	Funding: This work is supported by the US DOE SBIR program under contract number DE-SC0021511 and DE-SC0020573. Photocathodes of various materials are used in photoinjectors for generating photoelectron beams. Of particular interest are the alkali antimonides because of their ultra-high quantum efficiency (QE) and relatively low requirements for growth, and metallic materials such as Cu and Mg which have lower QE but are easier to maintain and have longer lifetime. The biggest challenge of using the alkali antimonide photocathode is that it has an extremely stringent requirement on vacuum and is destroyed rapidly by residual air in the system, while exposure of Mg and Cu in air also impacts the photocathode performance because of the oxidation. The photocathode can be protected against harmful gas molecules by using one or two monolayers of a 2D material such as graphene or hexagonal boron nitride (hBN). Furthermore, hBN monolayers even have the potential to improve the QE of the photocathode when working as the encapsulation thin-film. In this paper, we will discuss the feasibility of coating a photocathode with hBN by high power pulsed RF sputtering by using metallic photocathodes as examples, and compare the performance with encapsulated photocathodes with transferred hBN thin-films.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA56
About •	Received ※ 31 July 2022 — Revised ※ 04 August 2022 — Accepted ※ 08 August 2022 — Issue date ※ 10 August 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPA63	Extensions of the Complex (IQ) Baseband RF Cavity Model Including RF Source and Beam Interactions	767
	S.P. Jachim, B.J. Cook, J.R.S. Falconer Arizona State University, Tempe, USA
	Funding: This work was supported in part by NSF award #1935994. This paper extends prior work describing a complex envelope (i.e., baseband) dynamic model of excited accelerator RF cavities, including the effects of frequency detuning, beam loading, reflections, multiple drive ports, and parasitic modes. This model is presented here in closed-form transfer function and state-variable realizations, which may be more appropriate for analytic purposes. Several example simulations illustrate the detailed insight into RF system behavior afforded by this model.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA63
About •	Received ※ 28 July 2022 — Revised ※ 08 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 15 August 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPA64	Design and Commissioning of the ASU CXLS Machine Protection System	770
	S.P. Jachim, B.J. Cook, J.R.S. Falconer, A.J. Gardeck, W.S. Graves, M.R. Holl, R.S. Rednour, D.M. Smith, J.V. Vela Arizona State University, Tempe, USA
	Funding: This work was supported in part by NSF award #1935994. To protect against fault conditions in the high-power RF transport and accelerating structures of the Arizona State University (ASU) Compact X-Ray Light Source (CXLS), the Machine Protection System (MPS) extinguishes the 6.5-MW RF energy sources within approximately 50 ns of the fault event. In addition, each fault is localized and reported remotely via USB for operational and maintenance purposes. This paper outlines the requirements, design, and performance of the MPS applied on the CXLS.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA64
About •	Received ※ 13 July 2022 — Revised ※ 28 July 2022 — Accepted ※ 08 August 2022 — Issue date ※ 12 August 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPA77	A New PCB Rotating Coil at NSLS-II	816
	M. Musardo, J. Avronsart, F.A. DePaola, L. Doom, R. Faussete, F.C. Lincoln, S.K. Sharma, T. Tanabe BNL, Upton, New York, USA D. Assell, J. DiMarco Fermilab, Batavia, Illinois, USA A. Banerjee SBU, Stony Brook, New York, USA C.L. Doose, A.K. Jain ANL, Lemont, Illinois, USA
	Several R&D projects are underway at NSLS-II towards an upgrade of its storage ring with a new lattice that will use high field magnets with small bores of 16-22 mm. A large fraction of the high field magnets are expected to be of permanent magnet technology that will require precise magnetic measurements and field harmonics corrections. A new magnetic measurement bench has been built based on a printed circuit board (PCB) coil of 12 mm diameter and 270 mm active length. This PCB coil has the capabil-ity of measuring field quality to a level of 10 ppm of the main field up to the 15th harmonic with a sensitivity between 0.01 m2 and 0.02 m2 at the reference radius of 5 mm. This paper will describe the main features of the rotating coil bench and discuss the measurement results of a permanent-magnet Halbach quadrupole of 12.7 mm bore diameter.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA77
About •	Received ※ 28 July 2022 — Revised ※ 06 August 2022 — Accepted ※ 12 August 2022 — Issue date ※ 29 August 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEADE1	Integrating Diversity and Inclusion in the Workplace: Los Alamos National Laboratory’s Strategies for Expanding Diversity and Fostering Inclusion and Belonging
	K.S. Haight LANL, Los Alamos, New Mexico, USA
	Diversity fuels an innovative, agile and principled workforce that is essential to solving problems of global importance. Diversity of thought, experience, and perspective leads to better problem solving and promotes creativity. But diversity in the workplace does not organically grow without conscientious attention. Like growing a tree requires water, sun and fresh air, growing a diverse workforce requires awareness, strategy and reflection. Los Alamos National Laboratory’s approach to expanding diversity employs awareness, strategic action-oriented programs, and consistent reflection and rerouting to build a workforce that reflects the nation and world we are tasked to protect. But expanding diversity is meaningless without also fostering inclusion and belonging. Hear about successes and areas for further redirection from Los Alamos’s EEO and Affirmative Action Officer. Hear about the diversity of our Accelerator community and how this sector of our workforce compares to the broader community. And hear how the voices of our workforce are shaping our programs and initiatives to ensure that every unique voice, every idea and opinion, are welcome and respected.
	Slides WEADE1 [1.698 MB]
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THYE1	Overview of Superconducting Magnet Technologies
	S.O. Prestemon LBNL, Berkeley, California, USA
	Very high field superconducting magnets represent a critical technology for future accelerators, high field user magnets, and energy applications such as magnetic fusion and wind turbines. We discuss exciting technical developments in the field and the national and international communities efforts to organize R&D to advance the field.
	Slides THYE1 [12.687 MB]
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

SUXF1

Project Management and Accelerator Development

S. Biedron
Element Aero, Chicago, USA
L.M. Georgson Petrén
Roddare, Lund, Sweden

Accelerator laboratories belong to the largest research investments to be found regardless laboratory, research institute or country funding the initiatives. This impose a great responsibility on the researchers and engineers developing, building and updating research facilities. Accelerator development are important research projects and will affect many stakeholders regardless if it is a smaller upgrade of an RF system or development of a large scale FEL. Wet developing new systems project management is a core competence for every laboratory. Yet this is a knowledge area often ignored in favor skill development in areas closer to physics and technology. This can be a very expensive mistake as the value of proper project management cannot be underestimated. This half day training will give you insight in the basics of projects. What is a project and what does project management mean. And how can this be adopted in accelerator development.

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

SUZF1

Introduction to Systems Engineering Concepts

S. Biedron
Element Aero, Chicago, USA
L.M. Georgson Petrén
Roddare, Lund, Sweden

Systems engineering has long been employed in defense and non-defense industries but not commonly in particle accelerator systems. The common definition of Systems Engineering is as follows "It is a transdisciplinary and integrative approach to enable the successful realization, use, and retirement of engineered systems, using systems principles and concepts, and scientific, technological, and management methods." This overview introduces participants to the fundamental principles of systems engineering and their application to the development of complex systems. Systems engineering helps address engineering challenges as well as how systems engineering is essential to project management. The overview will help the participant learn the language of methods and processes commonplace in industry. We will define the following through examples: systems, the systems development lifecycle, and methods of systems engineering, beginning with the system requirements. One example will be exploring a novel particle accelerator through systems engineering methods.

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOODE4

PW-Class Lasers for Accelerators - Overview and an Industry Perspective

O.J. Chalus
THALES LAS France, Elancourt, France

In this presentation, we will review the current experiments done by various research group over the world on Laser assisted particle acceleration (BELLA, DESY, Weizmann…). We will spend a bit of time on the description of the laser technologies used for this. What are the specifications required for such laser, their footprint and their future development.

Slides MOODE4 [7.209 MB]

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOYE2

LCLS-II HE vCM Test Results: Newly Developed N-Doping Treatment and Plasma Processing

B. Giaccone
Fermilab, Batavia, Illinois, USA

This talk presents the results of the LCLS-II HE verification cryomodule (vCM), which aimed at verifing that the cryomodule is capable to meet the project specification (Q₀=2.7·10¹⁰ at 21 MV/m) with the newly developed nitrogen doping treatment. The test also carried out detailed studies on multipacting processing optimization and Q-factor quench degradation. Plasma processing was also carried out in four out of eight cavities in the cryomodule, showing its effectiveness in eliminating multipacting. These studies will be discussed.

Slides MOYE2 [9.629 MB]

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOYE3

Experiments on a Conduction Cooled Superconducting Radio Frequency Cavity with Field Emission Cathode

16

Y. Ji, R. Dhuley, C.J. Edwards, J.C.T. Thangaraj
Fermilab, Batavia, Illinois, USA
V. Korampally, D. Mihalcea, O. Mohsen, P. Piot, I. Salehinia
Northern Illinois University, DeKalb, Illinois, USA

Funding: The project is supported by DOE HEP Accelerator Stewardship award to Fermilab and Northern Illinois University
To achieve Ampere-class electron beam accelerators the pulse delivery rate need to be much higher than the typical photo injector repetition rate of the order of a few kilohertz. We propose here an injector which can, in principle, generate electron bunches at the same rate as the operating RF frequency. A conduction-cooled superconducting radio frequency (SRF) cavity operating in the CW mode and housing a field emission element at its region of high axial electric field can be a viable method of generating high-repetition-rate electron bunches. In this paper, we report the development and experiments on a conduction-cooled Nb₃Sn cavity with a niobium rod intended as a field emitter support. The initial experiments demonstrate ~0.4 MV/m average accelerating gradient, which is equivalent of peak gradient of 3.2 MV/m. The measured RF cavity quality factor is 1.4 × 10⁸ slightly above our goal. The achieved field gradient is limited by the relatively low input RF power and by the poor coupling between the external power supply and the RF cavity. With ideal coupling the field gradient can be as high as 0.6 MV/m still below our goal of about 1 MV/m

Slides MOYE3 [1.444 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOYE3

About •

Received ※ 01 August 2022 — Revised ※ 03 August 2022 — Accepted ※ 05 August 2022 — Issue date ※ 30 September 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOYE4

Diagnoses and Repair of a Crack in the Drift Tube LINAC Accelerating Structure at LANSCE

19

W.C. Barkley, D.A. Bingham, M.J. Borden, J.A. Burkhart, D.J. Evans, J.T.M. Lyles, J.P. Montross, J.F. O’Hara, B.J. Roller, M. Sanchez Barrueta
LANL, Los Alamos, New Mexico, USA

Funding: Work supported by the United States Department of Energy, National Nuclear Security Agency, under contract DE-AC52-06NA25396
Many were perplexed at the inability of Module 3 at LANSCE to operate at peak power and duty factor while running production beam. During the 2018 production run, the DTL began to intermittently break down, leading to a series of root cause investigations. These analyses included eliminating the usual suspects: vacuum leak, debris in tank, driveline window, power coupler, etc. The throttling back of repetition rate from 120 to 60 Hz allowed continued production with a diminished beam, one that reduced neutron flux to three experimental areas. During the annual shutdown in 2019, a more thorough investigation involving the use of x-ray detection, high-resolution cameras and IR detection through site glass windows was performed. After a tenacious search, a 30 cm long crack was discovered in a weld at one of the ion pump port grates. Inaccessibility for welding from the outside and in a confined space, non-intrusive repairs were tried first but were unsuccessful. Ultimately, an expert welder entered the tank to weld the crack under unfamiliar welding conditions. This paper describes the diagnoses, non-intrusive solutions and ultimate repair of the crack in the accelerating structure.

Slides MOYE4 [3.232 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOYE4

About •

Received ※ 23 July 2022 — Revised ※ 04 August 2022 — Accepted ※ 05 August 2022 — Issue date ※ 13 September 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOYE5

In Situ Plasma Processing of Superconducting Cavities at JLab

22

T. Powers, N.C. Brock, T.D. Ganey
JLab, Newport News, Virginia, USA

Jefferson Lab has an ongoing R&D program in plasma processing which is close to going into production processing in the CEBAF accelerator. Plasma processing is a common technique for removing hydrocarbons from surfaces, which increases the work function and reduces the secondary emission coefficient. Unlike helium processing which relies on ion bombardment of the field emitters, plasma processing uses free oxygen produced in the plasma to break down the hydrocarbons on the surface of the cavity. The initial focus of the effort was processing C100 cavities by injecting RF power into the HOM coupler ports. Results from processing cryomodule in the cryomodule test bunker as well as vertical test results will be presented. We plan to start processing cryomodules in the CEBAF tunnel within the next year. The goal will be to improve the operational gradients and the energy margin of the linacs. This work will describe the systems and methods used at JLAB for processing cavities using an argon oxygen gas mixture. Before and after plasma processing results will also be presented.

Slides MOYE5 [2.679 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOYE5

About •

Received ※ 01 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 01 October 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOYE6

Spin-Polarized Electron Photoemission and Detection Studies

26

A.C. Rodriguez Alicea, R. Palai
University of Puerto Rico, Rio Piedras Campus, San Juan, Puerto Rico
O. Chubenko, S.S. Karkare
Arizona State University, Tempe, USA
L. Cultrera
BNL, Upton, New York, USA

Funding: Brookhaven National Laboratory and the Department of Energy of United States under contract No. DE-SC0012704 Also, the Center for Bright Beams, NSF award PHY-1549132.
The experimental investigation of new photocathode ma- terials is time-consuming, expensive, and difficult to accom- plish. Computational modelling offers fast and inexpensive ways to explore new materials, and operating conditions, that could potentially enhance the efficiency of polarized electron beam photocathodes. We report on Monte-Carlo simulation of electron spin polarization (ESP) and quantum efficiency (QE) of bulk GaAs at 2, 77, and 300 K using the data obtained from Density Functional Theory (DFT) cal- culations at the corresponding temperatures. The simulated results of ESP and QE were compared with reported exper- imental measurements, and showed good agreement at 77 and 300 K.

Slides MOYE6 [6.235 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOYE6

About •

Received ※ 03 August 2022 — Revised ※ 07 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 04 September 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPA21

Effect of Electropolishing on Nitrogen Doped and Undoped Niobium Surfaces

93

V. Chouhan, F. Furuta, M. Martinello, T.J. Ring, G. Wu
Fermilab, Batavia, Illinois, USA

Cold electropolishing (EP) of a nitrogen-doped (N-doped) niobium (Nb) superconducting RF (SRF) cavity was found to improve its quality factor. In order to understand the effect of EP temperature on N-doped and undoped surfaces, a systematic EP study was conducted with 2/0 N-doped and heat-treated Nb samples in a beaker. The Nb samples were electropolished at different surface temperatures ranging from 0 to 42 C. The results showed that the doped surface was susceptible to the sample temperature during EP. EP resulted in the surface pitting on the doped samples where the number density of pits increased at a higher temperature. The surface results were compared with the surface of cutouts from a 9-cell cavity which was 2/0 N-doped and electropolished. This paper shows de-tailed surface features of the N-doped and undoped Nb surfaces electropolished at different temperatures.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA21

About •

Received ※ 20 July 2022 — Revised ※ 24 July 2022 — Accepted ※ 09 August 2022 — Issue date ※ 11 August 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPA22

Study on Electropolishing Conditions for 650 MHz Niobium SRF Cavity

97

V. Chouhan, D.J. Bice, F. Furuta, M. Martinello, M.K. Ng, H. Park, T.J. Ring, G. Wu
Fermilab, Batavia, Illinois, USA
B.M. Guilfoyle, M.P. Kelly, T. Reid
ANL, Lemont, Illinois, USA

The PIP II linear accelerator includes different types of niobium SRF cavities including 650 MHz elliptical low (0.61) and high (0.92) beta cavities. The elliptical cavity surface is processed with the electropolishing method. The elliptical cavities especially the low-beta 650 MHz cavities showed a rough equator surface after the EP was performed with the standard EP conditions. This work was focused to study the effect of different EP parameters, including cathode surface area, temperature and voltage, and optimize them to improve the cavity surface.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA22

About •

Received ※ 02 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 03 September 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPA23

Tests of the Extended Range SRF Cavity Tuners for the LCLS-II HE Project

100

C. Contreras-Martinez, T.T. Arkan, A.T. Cravatta, B.D. Hartsell, J.A. Kaluzny, T.N. Khabiboulline, Y.M. Pischalnikov, S. Posen, G.V. Romanov, J.C. Yun
Fermilab, Batavia, Illinois, USA

The LCLS-II HE superconducting linac will produce multi-energy beams by supporting multiple undulator lines simultaneously. This could be achieved by using the cavity SRF tuner in the off-frequency detune mode. This off-frequency operation method was tested in the verification cryomodule (vCM) and CM 1 at Fermilab at 2 K. In both cases, the tuners achieved a frequency shift of -565±80 kHz. This study will discuss cavity frequency during each step as it is being assembled in the cryomodule string and finally when it is being tested at 2 K. Tracking the cavity frequency helped enable the tuners to reach this large frequency shift. The specific procedures of tuner setting during assembly will be presented.

Poster MOPA23 [0.654 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA23

About •

Received ※ 03 August 2022 — Revised ※ 11 August 2022 — Accepted ※ 19 August 2022 — Issue date ※ 31 August 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPA24

LCLS-II and HE Cryomodule Microphonics at CMTF at Fermilab

103

C. Contreras-Martinez, B.E. Chase, A.T. Cravatta, J.A. Einstein-Curtis, E.R. Harms, J.P. Holzbauer, J.N. Makara, S. Posen, R. Wang
Fermilab, Batavia, Illinois, USA
L.R. Doolittle
LBNL, Berkeley, California, USA

Microphonics causes the cavity to detune. This study discusses the microphonics of 16 cryomodules, 14 for LCLS-II and 2 for LCLS-II HE tested at CMTF. The peak detuning, as well as the RMS detuning for each cryomodule, will be discussed. For each cryomodule, the data was taken with enough soaking time to prevent any thermalization effects which can show up in the detuning. Each data capture taken was 30 minutes or longer and sampled at 1 kHz.

Poster MOPA24 [1.428 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA24

About •

Received ※ 03 August 2022 — Revised ※ 10 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 20 September 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPA25

Simulated Lorentz Force Detuning Compensation with a Double Lever Tuner on a Dressed ILC/1.3 GHz Cavity at Room Temperature

106

C. Contreras-Martinez, Y.M. Pischalnikov, J.C. Yun
Fermilab, Batavia, Illinois, USA

Pulsed SRF linacs with high accelerating gradients experience large frequency shifts caused by Lorentz force detuning (LFD). A piezoelectric actuator with a resonance control algorithm can maintain the cavity frequency at the nominal level thus reducing the RF power. This study uses a double lever tuner with a piezoelectric actuator for compensation and another piezoelectric actuator to simulate the effects of the Lorentz force pulse. A double lever tuner has an advantage by increasing the stiffness of the cavity-tuner system thus reducing the effects of LFD. The tests are conducted at room temperature and with a dressed 1.3 GHz 9-cell cavity.

Poster MOPA25 [0.931 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA25

About •

Received ※ 03 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 13 August 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPA27

Validation of the 650 MHz SRF Tuner on the Low and High Beta Cavities for PIP-II at 2 K

109

C. Contreras-Martinez, S.K. Chandrasekaran, S. Cheban, G.V. Eremeev, I.V. Gonin, T.N. Khabiboulline, Y.M. Pischalnikov, O.V. Prokofiev, A.I. Sukhanov, J.C. Yun
Fermilab, Batavia, Illinois, USA

The PIP-II linac will include thirty-six B_G=0.61 and twenty-four B_G=0.92 650 MHz 5 cell elliptical SRF cavities. Each cavity will be equipped with a tuning system consisting of a double lever slow tuner for coarse frequency tuning and a piezoelectric actuator for fine frequency tuning. The same tuner will be used for both the B_G=0.61 and B_G=0.92 cavities. Results of testing the cavity-tuner system for the B_G=0.61 will be presented for the first time.

Poster MOPA27 [0.782 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA27

About •

Received ※ 03 August 2022 — Revised ※ 10 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 04 October 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPA30

LCLS-II BCS Average Current Monitor

120

N.M. Ludlow, T.L. Allison, J.P. Sikora, J.J. Welch
SLAC, Menlo Park, California, USA

LCLS-II is a 4th generation light source at the SLAC National Accelerator Laboratory. LCLS-II will accelerate a 30 µA electron beam with a 1 MHz bunch rate with a new superconducting Continuous Waveform (CW) RF accelerator. The Average Current Monitor (ACM) is part of the Beam Containment System (BCS) for the LCLS-II accelerator. The Beam Containment System is a safety system that provides paths to safely shut the accelerator beam off under a variety of conditions. The Average Current Monitor is a beam diagnostic within the BCS that is used to verify that the accelerator is producing the appropriate current level and to limit beam power to allowed values to protect the machine and beam dumps. The average beam current is obtained by measuring the power level induced by the beam in a low Q cavity. By knowing the Q, the beta, and the coupling of the cavity, the instantaneous charge can be calculated, then integrating the instantaneous charge over one millisecond will yield the average current. This paper will discuss progress in the checkout process of the ACM LLRF hardware leading to LCLS-II commissioning.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA30

About •

Received ※ 16 July 2022 — Revised ※ 05 August 2022 — Accepted ※ 24 August 2022 — Issue date ※ 06 October 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPA38

Accelerated Lifetime Test of the SRF Dressed Cavity/Tuner System for the LCLS II HE Project

136

Y.M. Pischalnikov, T.T. Arkan, C. Contreras-Martinez, B.D. Hartsell, J.A. Kaluzny, Y.M. Orlov, R.V. Pilipenko, J.C. Yun
Fermilab, Batavia, Illinois, USA
W. Lahmadi
Wahid Lahmadi, Williston, USA

The off-frequency detune method is being considered for application in the LCLS-II-HE superconducting linac to produce multi-energy electron beams for supporting multiple undulator lines simultaneously. Design of the tuner has been changed to deliver roughly 3 times larger frequency tuning range. Working requirements for off-frequency operation (OFO) state that cavities be tuned at least twice a month. This specification requires the increase of the tuner longevity by 30 times compared with LCLS-II demands. Accelerated longevity tests of the LCLS-II HE dressed cavity with tuner were conducted at FNAL’s HTS. Detail analysis of wearing and impacts on performances of the tuner’s piezo and stepper motor actuators will be presented. Additionally, results of longevity testing of the dressed cavity bellow, when cooled down to 2 K and compressed by 2.6 mm for roughly 2000 cycles, will be presented.

Poster MOPA38 [3.026 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA38

About •

Received ※ 29 July 2022 — Revised ※ 06 August 2022 — Accepted ※ 09 August 2022 — Issue date ※ 11 August 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPA42

Considerations Concerning the Use of HTS Conductor for Accelerator Dipoles with Inductions above 15 T

143

M.A. Green
LBNL, Berkeley, California, USA

Funding: This work was supported by the office of Science, under US Department of Energy contract number DE-AC-02-05CH11231.
The use of high temperature superconductors for accelerator dipole has been discussed for about twenty years and maybe a little more. Conductors that can potentially be used for accelerator magnets have been available for about fifteen years. These conductors are REBCO tape conductors, which can be wound into coils with no reaction after winding, and BISSCO cable conductors, which require reaction after winding and insulation after reaction in a process similar to Nb₃Sn cables. Both conductors are expensive and the process after reacting is expensive. Some unknown factors that remain: Will either conductor degrade in current carrying capacity with repeated cycling like Nb₃Sn cables do? The other two issues are problems for both types of HTS conductors and they are; 1) quench protection in the event of a normal region run-away and 2) dealing with the superconducting magnetization inherent with HTS cables and tapes. This paper will discuss the last two issues and maybe will provide a partial solution to these problems.

Poster MOPA42 [1.498 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA42

About •

Received ※ 01 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 23 August 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPA45

Vacuum Electron Devices in the 88-Inch Cyclotron

154

M. Kireeff Covo, J.Y. Benitez, P. Bloemhard, J.P. Garcia, B. Ninemire, L. Phair, D.S. Todd, D.Z. Xie
LBNL, Berkeley, California, USA

Funding: This work was supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under Contract No. DE-AC02-05CH11231
The 88-Inch Cyclotron at Lawrence Berkeley National Laboratory is a sector-focused cyclotron that has light- and heavy-ion capabilities and supports a local research program in Nuclear Science and is the home of the Berkeley Accelerator Space Effects Facility, which studies effects of radiation on microelectronics, optics, materials, and cells. The cyclotron utilizes several vacuum electron devices (VEDs) in different systems, mainly to convey plasma heating, high power RF generation, and high-voltage and current DC power generation. VEDs have been proven reliable, robust, and radiation resistant. They also have wide range, good response against transients, and stable operation with load mismatch during system tuning, instabilities, or breakdowns. The paper will describe applications of these devices in the 88-Inch Cyclotron

Poster MOPA45 [1.434 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA45

About •

Received ※ 02 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 12 September 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPA59

Prediction of Gaseous Breakdown for Plasma Cleaning of RF Cavities

174

S.A. Ahmed
Ansys, Inc., Canonsburg, USA

The quest for a high accelerating gradient in superconducting radio frequency cavity attracted scientists to adopt the plasma cleaning technology. Generating an efficient plasma inside a complex cavity structure for a desired frequency, gas types, and pressure for a given temperature is a challenge. The onset of discharge can be obtained from the well-known Paschen curve. Setting up an experiment is expensive and time-consuming, which may lead to a significant delay in the project. A high-fidelity computer simulation, modeling an arbitrary geometry and tracking the Paschen curve in a complex electromagnetic environment is therefore necessary. Ansys HFSS through its Finite Element Mesh (FEM) for the full-wave EM simulations combined with the electron impact ionization of gases enables the successful prediction of plasma breakdown for an arbitrary configuration for a wide frequency band and variety of gases. A comprehensive study will be demonstrated at the conference.
The author like to thank Robert Chao for the valuable discussions and his efforts in developing this capability in the Ansys Electronics Desktop.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA59

About •

Received ※ 01 August 2022 — Revised ※ 03 August 2022 — Accepted ※ 06 August 2022 — Issue date ※ 19 August 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPA61

Modular Solid-State Switching and Arc Suppression for Vacuum Tube Bias Circuits

179

E.L. Atkinson, T.J. Houlahan, B.E. Jurczyk, R.A. Stubbers
Starfire Industries LLC, Champaign, USA

In this work, we present operational and performance data for a solid-state switching circuit that delivers pulsed power at up to 12 kV and 100 A. This circuit, which is comprised of a series configuration of IGBT-based subcircuits, is suitable for driving the high-power vacuum-tube amplifiers that are typically used in RF accelerator systems. Each subcircuit can switch up to 3 kV, and the subcircuits can be stacked in series to extend the overall voltage capabilities of the switch. The circuit is designed to prevent overvoltaging any single transistor during switching transients or faults, regardless of the number of series subcircuits. Further, the circuit also includes the capability for rapid arc detection and suppression. Testing has shown effective switching at up to 100 A at 12 kV and for pulse repetition frequencies and durations in the range of 1-200 Hz and 10-50 µs, respectively. Additionally, the arc suppression circuitry has been shown to reliably limit arcs at 8-12 kV with a quench time of <1 µs and with a total energy of <0.2 J, minimizing the grid erosion in the vacuum-tube during an arc.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA61

About •

Received ※ 01 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 20 August 2022 — Issue date ※ 10 September 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPA62

High Quality Conformal Coatings on Accelerator Components via Novel Radial Magnetron with High-Power Impulse Magnetron Sputtering

182

W.M. Huber, I. Haehnlein, T.J. Houlahan, B.E. Jurczyk, A.S. Morrice, R.A. Stubbers
Starfire Industries LLC, Champaign, USA

Funding: This material is based upon work supported by the U.S. Department of Energy under Award Numbers DE-SC0019784 and DE-SC0020481.
In this work, we present two configurations of a novel radial magnetron design that are suitable for coating the complex inner surfaces of a variety of modern particle accelerator components. These devices have been used in conjunction with high-power impulse magnetron sputtering (HiPIMS) to deposit copper and niobium films onto the inner surfaces of bellows assemblies, waveguides, and SRF cavities. These films, with thicknesses of up to 3 µm and 40 µm for niobium and copper, respectively, have been shown to be conformal, adherent, and conductive. In the case of copper, the post-bake RRR values of the resulting films are well within the range specified for electroplating of the LCLS-II bellows and CEBAF waveguide assemblies. In addition to requiring no chemical processing beyond a detergent rinse and solvent degrease, this magnetron design exhibits over 80% target material utilization. Further, in the case of niobium, an enhancement in RRR over that of the bulk (target) material has been observed.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA62

About •

Received ※ 02 August 2022 — Revised ※ 05 August 2022 — Accepted ※ 09 August 2022 — Issue date ※ 21 August 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPA63

Multiphysics Simulation of the Thermal Response of a Nanofibrous Target in a High-Intensity Beam

185

W.J. Asztalos
IIT, Chicago, Illinois, USA
S.K. Bidhar, F. Pellemoine
Fermilab, Batavia, Illinois, USA
P. Rath
IIT Bhubaneswar, Jatni, India
Y. Torun
Illinois Institute of Technology, Chicago, Illlinois, USA

Nanofibrous structures are of high interest to the fields of engineering and materials science, and investigation of their properties as well as discovery of novel applications for them both constitute lively areas of research. A very promising application of nanofiber mats lies in the field of accelerator technology: beam targets made from nanofiber mats offer a solution to the problem of advancing the "intensity frontier"–-the limit on the beam intensities that can be realized in fixed target experiments and neutrino production facilities. However, testing has shown that the survivability of these nanofiber targets depends strongly on their manufacturing parameters, such as the packing density of fibers. In this work, we will use multiphysics simulations to perform a thermal study on how nanofiber targets react to high intensity beams, so that the dependency of the targets’ lifetime on their construction parameters can be better understood.

Poster MOPA63 [3.656 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA63

About •

Received ※ 14 July 2022 — Revised ※ 02 August 2022 — Accepted ※ 04 August 2022 — Issue date ※ 25 August 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPA67

Examining the Effects of Oxygen Doping on SRF Cavity Performance

196

H. Hu, Y.K. Kim
University of Chicago, Chicago, Illinois, USA
D. Bafia
Fermilab, Batavia, Illinois, USA

Superconducting radiofrequency (SRF) cavities are resonators with extremely low surface resistance that enable accelerating cavities to have extremely high quality factors (Q₀). High (Q₀) decreases the capital required to keep accelerators cold by reducing power loss. The performance of SRF cavities is largely governed by the surface composition of the first 100 nm of the cavity surface. Impurities such as oxygen and nitrogen have been observed to yield high Q₀, but their precise roles are still being studied. Here, we compare the performance of cavities doped with nitrogen and oxygen in terms of fundamental material properties to understand how these impurities affect performance. This enables us to have further insight into the underlying mechanisms that enable these surface treatments to yield high Q₀ performance.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA67

About •

Received ※ 02 August 2022 — Accepted ※ 05 August 2022 — Issue date ※ 03 October 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPA83

Automation of Superconducting Cavity and Superconducting Magnet Operation for FRIB

239

W. Chang, Y. Choi, X.-J. Du, W. Hartung, S.H. Kim, T. Konomi, S.R. Kunjir, H. Nguyen, J.T. Popielarski, K. Saito, T. Xu, S. Zhao
FRIB, East Lansing, Michigan, USA

The superconducting (SC) driver linac for the Facility for Rare Isotope Beams (FRIB) is a heavy-ion accelerator that accelerate ions to 200 MeV per nucleon. The linac has 46 cryomodules that contain 324 SC cavities and 69 SC solenoid packages. For linac operation with high availability and high reliability, automation is essential for such tasks as fast device turn-on/off, fast recovery from trips, and real-time monitoring of operational performance. We have implemented several automation algorithms, including one-button turn-on/off of SC cavities and SC magnets; automated degaussing of SC solenoids; mitigation of field emission-induced multipacting during recovery from cavity trips; and real-time monitoring of the cavity field level calibration. The design, development, and operating experience with automation will be presented.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA83

About •

Received ※ 02 August 2022 — Revised ※ 03 August 2022 — Accepted ※ 06 August 2022 — Issue date ※ 26 August 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPA84

Superconducting Cavity Commissioning for the FRIB Linac

242

W. Chang, W. Hartung, S.H. Kim, T. Konomi, S.R. Kunjir, J.T. Popielarski, K. Saito, T. Xu, S. Zhao
FRIB, East Lansing, Michigan, USA

The superconducting driver linac for the Facility for Rare Isotope Beams (FRIB) is a heavy ion accelerator that has 46 cryomodules with 324 superconducting (SC) cavities that accelerate ions to 200 MeV per nucleon. Linac commissioning was done in multiple phases, in parallel with technical installation. Ion beam have now been accelerated to the design energy through the full linac; rare isotopes were first produced in December 2021; and the first user experiment was completed in May 2022. All cryomodules were successfully commissioned. Cryomodule commissioning included establishing the desired cavity fields, measuring field emission X-rays, optimizing the tuner control loops, measuring the cavity dynamic heat load, and confirming the low-level RF control (amplitude and phase stability). Results on cryomodule commissioning and cryomodule performance will be presented.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA84

About •

Received ※ 13 July 2022 — Revised ※ 02 August 2022 — Accepted ※ 13 August 2022 — Issue date ※ 05 September 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPA85

Design of a 185.7 MHz Superconducting RF Photoinjector Quarter-Wave Resonator for the LCLS-II-HE Low Emittance Injector

245

S.H. Kim, W. Hartung, T. Konomi, S.J. Miller, M.S. Patil, J.T. Popielarski, K. Saito, T. Xu, T. Xu
FRIB, East Lansing, Michigan, USA
C. Adolphsen, L. Ge, F. Ji, J.W. Lewellen, L. Xiao
SLAC, Menlo Park, California, USA
M.P. Kelly, T.B. Petersen, P. Piot
ANL, Lemont, Illinois, USA
P. Piot
Northern Illinois University, DeKalb, Illinois, USA

Funding: Work supported by the U.S. Department of Energy Contract DE-AC02-76SF00515.
A 185.7 MHz superconducting quarter-wave resonator (QWR) was designed for the low emittance injector of the Linac Coherent Light Source high energy upgrade (LCLS-II-HE). The cavity was designed to minimize the risk of cathode efficiency degradation due to multipacting or field emission and to operate with a high RF electric field at the cathode for low electron-beam emittance. Cavity design features include: (1) shaping of the cavity wall to reduce the strength of the low-field coaxial multipacting barrier; (2) four ports for electropolishing and high-pressure water rinsing; and (3) a fundamental power coupler (FPC) port located away from the accelerating gap. The design is oriented toward minimizing the risk of particulate contamination and avoid harmful dipole components in the RF field. The ANL 162 MHz FPC design for PIP-II is being adapted for the gun cavity. We will present the RF design of the cavity integrated with the FPC.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA85

About •

Received ※ 03 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 30 August 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPA86

Conditioning of Low-Field Multipacting Barriers in Superconducting Quarter-Wave Resonators

249

S.H. Kim, W. Chang, W. Hartung, J.T. Popielarski, T. Xu
FRIB, East Lansing, Michigan, USA

Funding: This is based upon work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661, the State of Michigan and Michigan State University.
Multipacting (MP) barriers are typically observed at very low RF amplitude, at a field 2 to 3 orders of magnitude below the operating gradient, in low-frequency (<~100 MHz), quarter-wave resonators (QWRs). Such barriers may be troublesome, as RF conditioning with a fundamental power coupler (FPC) of typical coupling strength (external Q = 10⁶ to 10⁷) is generally difficult. For the FRIB \beta = 0.085 QWRs (80.5 MHz), the low barrier is observed at an accelerating gradient (E_acc) of ~10 kV/m; the operating E_acc is 5.6 MV/m. Theoretical and simulation studies suggested that the conditioning is difficult due to the relatively low RF power dissipated into multipacting rather than being a problem of the low barrier being stronger than other barriers. We developed a single-stub coaxial FPC matching element for external adjustment of the external Q by one order of magnitude. The matching element provided a significant reduction in the time to condition the low barrier. We will present theoretical and simulation studies of the low MP barrier and experimental results on MP conditioning with the single-stub FPC matching element.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA86

About •

Received ※ 03 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 21 August 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPA87

Design of the Cathode Stalk for the LCLS-II-HE Low Emittance Injector

253

T. Konomi, W. Hartung, S.H. Kim, S.J. Miller, D.G. Morris, J.T. Popielarski, K. Saito, A. Taylor, T. Xu
FRIB, East Lansing, Michigan, USA
C. Adolphsen, J.W. Lewellen
SLAC, Menlo Park, California, USA
S. Gatzmaga, P. Murcek, R. Xiang
HZDR, Dresden, Germany
M.P. Kelly, T.B. Petersen
ANL, Lemont, Illinois, USA

Superconducting radio-frequency (SRF) electron guns are attractive for delivery of beams at a high bunch repetition rate with a high accelerating field. An SRF gun is the most suitable injector for the high-energy upgrade of the Linac Coherent Light Source (LCLS-II-HE), which will produce high-energy X-rays at high repetition rate. An SRF gun is being developed for LCLS-II-HE as a collaborative effort by FRIB, HZDR, ANL, and SLAC. The cavity operating frequency is 185.7 MHz, and the target accelerating field at the photocathode is 30 MV/m. The photocathode is replaceable. The cathode is held by a fixture (’cathode stalk’) that is designed for thermal isolation and particle-free cathode exchange. The stalk must allow for precise alignment of the cathode position, cryogenic or room-temperature cathode operating temperature, and DC bias to inhibit multipacting. We are planning a test of the stalk to confirm that the design meets the requirements for RF power dissipation and biasing. In this presentation, we will describe the cathode stalk design and RF/DC stalk test plan.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA87

About •

Received ※ 04 August 2022 — Revised ※ 11 August 2022 — Accepted ※ 18 August 2022 — Issue date ※ 11 September 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPA91

Plasma Processing of Superconducting Quarter-Wave Resonators Using a Higher-Order Mode

267

W. Hartung, W. Chang, K. Elliott, S.H. Kim, T. Konomi, J.T. Popielarski, K. Saito, T. Xu
FRIB, East Lansing, Michigan, USA

The Facility for Rare Isotope Beams (FRIB) is a superconducting ion linac with acceleration provided by 104 quarter-wave resonators (QWRs) and 220 half-wave resonators (HWRs); FRIB user operations began in May 2022. Plasma cleaning is being developed as a method to mitigate possible future degradation of QWR or HWR performance: in-situ plasma cleaning represents an alternative to removal and disassembly of cryomodules for refurbishment of each cavity via repeat etching and rinsing. Initial measurements were done on a QWR and an HWR with room-temperature-matched input couplers to drive the plasma via the fundamental mode. Subsequent plasma cleaning tests were done on two additional FRIB QWRs using the fundamental power coupler (FPC) to drive the plasma. When using the FPC, a higher-order mode (HOM) at 5 times the accelerating mode frequency was used to drive the plasma. Use of the HOM allowed for less mismatch at the FPC and hence lower field in the coupler relative to the cavity. A neon-oxygen gas mixture was used for plasma generation. Before and after cold tests showed a significant reduction in field emission X-rays after plasma cleaning. Results will be presented.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA91

About •

Received ※ 12 August 2022 — Revised ※ 16 August 2022 — Accepted ※ 25 August 2022 — Issue date ※ 16 September 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPA02

Characterization of Octupole Elements for IOTA

351

J.N. Wieland
MSU, East Lansing, Michigan, USA
J.D. Jarvis, A.L. Romanov, A. Valishev
Fermilab, Batavia, Illinois, USA

Funding: Work partially supported by the US Department of Energy, Office of Science, High Energy Physics under Cooperative Agreement award number DE-SC0018362 and Michigan State University.
The Integrable Optics Test Accelerator (IOTA) is a research storage ring constructed and operated at Fermilab to demonstrate the advantages of nonlinear integrable lattices. One of the nonlinear lattice configurations with one integral of motion is based on a string of short octupoles. The results of the individual magnet’s characterizations, which were necessary to determine their multipole composition and magnetic centers, are presented. This information was used to select and align the best subset of octupoles for the IOTA run 4.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA02

About •

Received ※ 03 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 09 August 2022 — Issue date ※ 08 September 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPA11

Magnet System for a Compact Microtron Source

363

S.A. Kahn, R.J. Abrams, M.A. Cummings, R.P. Johnson, G.M. Kazakevich
Muons, Inc, Illinois, USA

Funding: Work supported in part by U.S. D.O.E. SBIR grant DE-SC0013795.
A microtron can be an effective intense electron source. It can use less RF power than a linac to produce a similar energy because the beam will pass through the RF cavity several times. To produce a high-quality low-emittance beam with a microtron requires a magnetic system with a field uniformity $δ B/B<0.001. Field quality for a compact microtron with fewer turns is more difficult to achieve. In this study we describe the magnet for a compact S-band microtron that will achieve the necessary field requirements. The shaping of the magnet poles and shimming of the magnet iron at the outer extent of the poles will be employed to provide field uniformity. The extraction of the beam will be discussed.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA11

About •

Received ※ 04 August 2022 — Revised ※ 14 August 2022 — Accepted ※ 06 September 2022 — Issue date ※ 08 October 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPA13

Affordable, Efficient Injection-Locked Magnetrons for Superconducting Cavities

366

M. Popovic, M.A. Cummings, R.P. Johnson, S.A. Kahn, R.R. Lentz, M.L. Neubauer, T. Wynn
Muons, Inc, Illinois, USA
T. Blassick, J.K. Wessel
Richardson Electronics Ltd, Lafox, Illinois, USA

Funding: DE-SC0022586.
Existing magnetrons that are typically used to study methods of control or lifetime improvements for SRF accelerators are built for much different applications such kitchen microwave ovens (1kW, 2.45 GHz) or industrial heating (100 kW, 915 MHz). In this project, Muons, Inc. will work with an industrial partner to develop fast and flexible manufacturing techniques to allow many ideas to be tested for construction variations that enable new phase and amplitude injection locking control methods, longer lifetime, and inexpensive refurbishing resulting in the lowest possible life-cycle costs. In Phase II magnetron sources will be tested on SRF cavities to accelerate an electron beam at JLab. A magnetron operating at 650 MHz will be constructed and tested with our novel patented subcritical voltage operation methods to drive an SRF cavity. The choice of 650 MHz is an optimal frequency for magnetron efficiency. The critical areas of magnetron manufacturing and design affecting life-cycle costs that will be modeled for improvement include: Q_ext, filaments, magnetic field, vane design, and novel control of outgassing.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA13

About •

Received ※ 05 August 2022 — Revised ※ 11 August 2022 — Accepted ※ 12 August 2022 — Issue date ※ 23 August 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPA15

Development of a CVD System for Next-Generation SRF Cavities

372

G. Gaitan, P. Bishop, A.T. Holic, G. Kulina, J. Sears, Z. Sun
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
M. Liepe
Cornell University, Ithaca, New York, USA
B.W. Wendland
University of Minnesota, Minnesota, USA

Funding: This research is funded by the National Science Foundation under Grant No. PHY-1549132, the Center for Bright Beams.
Next-generation, thin-film surfaces employing Nb₃Sn, NbN, NbTiN, and other compound superconductors are destined to allow reaching superior RF performance levels in SRF cavities. Optimized, advanced deposition processes are required to enable high-quality films of such materials on large and complex-shaped cavities. For this purpose, Cornell University is developing a remote plasma-enhanced chemical vapor deposition (CVD) system that facilitates coating on complicated geometries with a high deposition rate. This system is based on a high-temperature tube furnace with a clean vacuum and furnace loading system. The use of plasma alongside reacting precursors will significantly reduce the required processing temperature and promote precursor decomposition. The system can also be used for annealing cavities after the CVD process to improve the surface layer. The chlorine precursors have the potential to be corrosive to the equipment and pose specific safety concerns. A MATLAB GUI has been developed to control and monitor the CVD system at Cornell.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA15

About •

Received ※ 14 July 2022 — Revised ※ 08 August 2022 — Accepted ※ 09 August 2022 — Issue date ※ 22 August 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPA21

Hydrodynamic and Beam Dynamic Simulations of Ultra-Low Emittance Whole Beam Dumps in the Advanced Photon Source Storage Ring

390

J.C. Dooling, M. Borland, A.M. Grannan, C.J. Graziani, Y. Lee, R.R. Lindberg, G. Navrotski
ANL, Lemont, Illinois, USA
N.M. Cook
RadiaSoft LLC, Boulder, Colorado, USA
D.W. Lee
UCSC, Santa Cruz, California, USA

Funding: Work supported by Accelerator Science and Technology LDRD Project 2021-0119 and the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
The Advanced Photon Source Upgrade will use a multi-bend achromatic lattice to reduce vertical and horizontal beam emittances by one- and two-orders of magnitude respectively; in addition operating current will double. The resulting electron beam will be capable of depositing more than 150 MGy on machine protection collimators creating high-energy-density conditions. Work is underway to couple the beam dynamics code Elegant with the particle-matter interaction program MARS and the magnetohydrodynamics code FLASH to model the effects of whole beam dumps on the collimators. Loss distributions from Elegant are input to MARS which provide dose maps to FLASH. We also examine the propagation of downstream shower components after the beam interacts with the collimator. Electrons and positrons are tracked to determine locations of beam loss. Beam dump experiments conducted in the APS storage-ring, generated dose levels as high as 30 MGy resulting in severe damage to the collimator surfaces with melting in the bulk. The deformed collimator surface may lead to beam deposition in unexpected locations. A fan-out kicker is planned to mitigate the effects of whole beam dumps on the collimators.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA21

About •

Received ※ 02 August 2022 — Revised ※ 10 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 10 September 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPA33

Magnetic Field Calculation of Superconducting Undulators for FEL Using Maxwell 3D

423

Y. Shiroyanagi, Y. Ivanyushenkov, M. Kasa
ANL, Lemont, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.
An ANL-SLAC collaboration is working on design of a planar superconducting undulator (SCU) demonstrator for a FEL. As a part of this project, a SCU magnet prototype is planned to be built and tested. A planar SCU magnet consisting of a 1.0-m-long segment is being designed. Although OPERA is a standard tool for magnetic field calculation, ANSYS Maxwell 3D can also be used for a large and complex geometry. An ANSYS calculated magnetic field was benchmarked with the measured field profile of existing SCUs. This paper presents calculations of magnetic field and field integrals of 0.5-m-long and 1.0-m-long planar SCUs with a new end correction scheme. Then, an external phase shifter is also incorporated into the model. A cross-talk between a phase shifter and SCU magnetic structures is also presented.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA33

About •

Received ※ 02 August 2022 — Revised ※ 03 August 2022 — Accepted ※ 05 August 2022 — Issue date ※ 25 August 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPA44

A Personal History of the Development of the LAMPF/LANSCE Accelerator

449

J.M. Potter
JP Accelerator Works, Los Alamos, New Mexico, USA

The LAMPF/LANSCE accelerator has now been operational for 50 years. I arrived as a LASL employee in Group P11 in April 1964 at the beginning stages of its development. I participated in the development of the resonant coupling principle [1] and went on to develop tuning procedures for the 805-MHz coupled cavity linac (CCL) structures and the post-stabilized drift tube linac (DTL) [2]. The resonant coupling principle is now well established as the basis for rf linear accelerators worldwide. I will discuss the development and building of the accelerator from my viewpoint as a member of a large, dedicated team of physicists, engineers, technicians, and support personnel.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA44

About •

Received ※ 02 August 2022 — Revised ※ 04 August 2022 — Accepted ※ 05 August 2022 — Issue date ※ 05 September 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPA52

Initial Results of the 201.25 MHz Coaxial Window Test Stand

458

T.W. Hall, J.T.M. Lyles, A. Poudel, A.S. Waghmare
LANL, Los Alamos, New Mexico, USA

We have recently commissioned an RF window test stand for the Drift Tube Linear Accelerator (DTL) portion of the Los Alamos Neutron Science Center (LANSCE). The window test stand consists of two RF windows that create a vacuum chamber which allows the windows to be tested to the peak power levels used in the DTL. Initial results clearly indicated multipactoring due to the increase of pressure at specific regions of peak forward power levels. Temperature measured at various azimuthal locations on both windows showed increased multipactor heating on the downstream window versus the upstream window. We present the effect of the titanium nitride coating that is presently applied to windows on both multipactor and window temperature. These results are discussed with respect to their impact on the LANSCE DTL performance.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA52

About •

Received ※ 25 July 2022 — Revised ※ 04 August 2022 — Accepted ※ 05 August 2022 — Issue date ※ 07 September 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPA59

RF System Upgrade for Low Energy DTL Cavity at LANSCE

478

J.T.M. Lyles, R.E. Bratton, T.W. Hall, M. Sanchez Barrueta
LANL, Los Alamos, New Mexico, USA

Funding: Work supported by the United States Department of Energy, National Nuclear Security Agency, under contract 89233218CNA000001.
The Los Alamos Neutron Science Center (LANSCE) 100-MeV Drift Tube Linac (DTL) uses four accelerating cavities. In May of 2021, a new RF amplifier system was commissioned to drive the first 4-MeV cavity. It had been powered for 30 years with a triode vacuum tube RF amplifier driven by a tetrode, along with four more vacuum tubes for anode high-voltage modulation. The new amplifier system uses one tetrode amplifier driven by a 20-kW solid state amplifier (SSA) to generate 400 kWp at 201.25 MHz. The tetrode amplifier is protected for reflected power from the DTL by a coaxial circulator. The new installation includes cRio controls and a fast protection and monitoring system capable of reacting to faults within 10 µs. A new digital low-level RF (LLRF) system has been installed that integrates I/Q signal processing, PI feedback, and feedforward controls for beam loading compensation. Issues with LLRF stability were initially encountered due to interaction from thermal-related RF phase changes. After these issues were solved, the final outcome has been a reliable new RF system to complete the overall upgrade of the LANSCE DTL RF power plant.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA59

About •

Received ※ 03 August 2022 — Revised ※ 04 August 2022 — Accepted ※ 06 August 2022 — Issue date ※ 12 August 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPA64

Analysis of Resonant Converter Topology for High-Voltage Modulators

486

M. Sanchez Barrueta, J.T.M. Lyles, M.D.M. Morris
LANL, Los Alamos, New Mexico, USA

Funding: Work Supported by the United States Department of Energy, National Nuclear Security Agency, under contract DE-AC52-06NA25396
At the Los Alamos Neutron Science Center (LANSCE), we are considering various topologies to replace obsolete charging supplies and capacitor banks that provide high-voltage direct-current (DC) power to the 44, 805-MHz klystron modulators that drive the LANSCE Coupled Cavity Linac (CCL). Among the possible replacement topologies is the High Voltage Converter Modulator (HVCM), originally designed at LANSCE for use at the Spallation Neutron Source (SNS), to be used as a pulsed high-voltage power supply for klystron-based RF transmitters. The HVCM topology uses high frequency transformers with resonant LC networks for efficient energy conversion and a frequency dependent gain, which permits the use of frequency modulation as a control variable to afford pulse flattening and excellent regulation as demonstrated at SNS. A mathematical analysis is presented that links the converter resonant tank components to the frequency dependent output behavior of the converter modulator.
LA-UR-22-25179

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA64

About •

Received ※ 03 August 2022 — Revised ※ 10 August 2022 — Accepted ※ 12 August 2022 — Issue date ※ 22 August 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPA69

Improving Cavity Phase Measurements at Los Alamos Neutron Science Center

493

P. Van Rooy, A.T. Archuleta, L.J. Castellano, S. Kwon, M.S. Prokop, P.A. Torrez
LANL, Los Alamos, New Mexico, USA

Control stability of the phase and amplitude in the cavity is a significant contributor to beam performance. The ability to measure phase and amplitude of pulsed RF systems at accuracies of ± 0.1 degrees and ± 0.1 percent required for our systems is difficult, and custom-designed circuitry is required. The digital low-level RF upgrade at the Los Alamos Neutron Science Center is continuing to progress with improved cavity phase measurements. The previous generation of the cavity phase and amplitude measurement system has a phase ambiguity, which requires repeated calibrations to ascertain the correct phase direction. The new phase measurement system removes the ambiguity and the need for field calibration while improving the range and precision of the cavity phase measurements. In addition, the new digital low-level RF systems is designed to upgrade the legacy system without significant mechanical, electrical, or cabling changes. Performance data for the new phase measurement system is presented.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA69

About •

Received ※ 02 August 2022 — Revised ※ 11 August 2022 — Accepted ※ 21 August 2022 — Issue date ※ 08 September 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPA73

Design and Low Power Test of an Electron Bunching Enhancer Using Electrostatic Potential Depression

499

H. Xu, B.E. Carlsten, Q.R. Marksteiner
LANL, Los Alamos, New Mexico, USA
B.L. Beaudoin, T.W. Koeth, A. Ting
UMD, College Park, Maryland, USA

Funding: This project was supported by the U.S. Department of Energy Office of Science through the Accelerator Stewardship Program.
We present our experimental design and low power test results of a structure for the proof-of-principle demonstration of fast increase of the first harmonic current content in a bunched electron beam, using the technique of electrostatic potential depression (EPD). A primarily bunched electron beam from an inductive output tube (IOT) at 710 MHz first enters an idler cavity, where the longitudinal slope of the beam energy distribution is reversed. The beam then transits through an EPD section implemented by a short beam pipe with a negative high voltage bias, inside which the rate of increase of the first harmonic current is significantly enhanced. An output cavity measures the harmonic current developed inside the beam downstream of the EPD section. Low power test results of the idler and the output cavities agree with the theoretical design.

Poster TUPA73 [1.307 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA73

About •

Received ※ 29 July 2022 — Accepted ※ 03 August 2022 — Issue date ※ 09 August 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEXE1

Accelerator Science and Technology via Inventive Principles of TRIZ

A. Seryi
JLab, Newport News, Virginia, USA

A swift overview of modern areas of accelerator physics and technology presented via and connected through inventive principles of TRIZ, the industrial methodology of inventiveness. A wide range of topics, such as synchrotron radiation, electron cooling, plasma acceleration, are introduced via easy-to-follow back-of-the-envelope derivations. These are connected via canonical yet adjusted for science TRIZ inventive principles and laws, illustrated by numerous inventions such as fiber lasers, tune jumps, inverted guns, and others. This short tutorial introduces a new approach which amalgamates science and industrial inventiveness, enhances creativity, and boosts innovations towards developing the next generations of accelerators and their applications.

Slides WEXE1 [16.003 MB]

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEZD1

ARDAP’s Perspective on Accelerator Technology R&D in the U.S.

592

B.E. Carlsten, E.R. Colby, R.A. Marsh, M. White
ARDAP, Washington, USA

DOE operates several particle accelerator facilities and is planning several new forward-leaning accelerator facilities over the next decade or two. These new facilities will focus on discovery science research and fulfilling other core DOE missions. Near and mid-term examples include PIP-II and FACET-II (for High Energy Physics); LCLS-II, SNS-PPU, APS-U, and ALS-U (for Basic Energy Sciences); FRIB (for Nuclear Physics); NSTX-U and MPEX (for Fusion Energy Sciences); and Scorpius (for NNSA). Longer-term examples may include future colliders, the SNS-STS, LCLS-II HE, and EIC. In addition to domestic facilities, DOE’s Office of Science (SC) also contributes to several international efforts. Together, these new facilities constitute a multibillion-dollar construction and operations investment. To be successful, they will require advances in state-of-the-art accelerator technologies. They will also require the National Laboratories to procure a variety of accelerator components. This paper summarizes how DOE is working to address these upcoming R&D and accelerator component production needs through its new office of Accelerator R&D and Production (ARDAP).

Slides WEZD1 [2.310 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEZD1

About •

Received ※ 05 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 19 August 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEZD2

Solid State Active Reset Induction Technology to Accelerate kA Electron Beam

J. Ellsworth
LLNL, Livermore, USA

We will discuss Solid State Active reset technology and how it can be applied to kA electron beams.

Slides WEZD2 [2.871 MB]

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEZD3

Magnetron R&D Progress for High Efficiency CW RF Sources of Industrial Accelerators

597

H. Wang, K. Jordan, R.M. Nelson, S.A. Overstreet, R.A. Rimmer
JLab, Newport News, Virginia, USA
J.N. Blum
VCU, Richmond, Virginia, USA
B.R.L. Coriton, C.P. Moeller, K.A. Thackston
GA, San Diego, California, USA
J.L. Vega
The College of William and Mary, Williamsburg, Virginia, USA
G. Ziemyte
UKY, Kentucky, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177, and DOE OS/HEP Accelerator Stewardship award 2019-2022.
After the demonstration of using high efficiency magnetron power to combine and aim to drive a radio frequency accelerator at 2450MHz in CW mode [1], we have used trim coils adding to a water-cooled magnetron and three amplitude modulation methods in an open-loop control to further suppress the 120Hz side-band noise to -46.7dBc level. We have also successfully demonstrated the phase-locking to an industrial grade cooking magnetron transmitter at 915MHz with a 75kW CW power delivered to a water load by using a -26.6dBc injection signal. The sideband noise at 360Hz from the 3-Phase SCRs DC power supply can be reduced to -16.2dBc level. Their power combing scheme and higher power application to industrial accelerators are foreseeing.
[1] H. Wang, et al, Magnetron R&D for High Efficiency CW RF Sources for Industrial Accelerators, TUPAB348, 12th Int. Particle Acc. Conf. IPAC2021, Campinas, SP, Brazil.

Slides WEZD3 [3.074 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEZD3

About •

Received ※ 18 July 2022 — Revised ※ 25 July 2022 — Accepted ※ 08 August 2022 — Issue date ※ 11 August 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEZD4

Using Off-Axis Undulator Radiation as a Longitudinal Electron-Beam Diagnostic

Q.R. Marksteiner, H.L. Andrews, J.E. Coleman, W.P. Romero, N.A. Yampolsky, M.R.A. Zuboraj
LANL, Los Alamos, New Mexico, USA
S.K. Barber, R.D. Ryne, J. van Tilborg
LBNL, Berkeley, USA
C. Emma
SLAC, Menlo Park, California, USA
B. Ostler
University of Chicago, Chicago, Illinois, USA

Funding: This project was supported by funding from the Los Alamos National Laboratory Laboratory Research and Development program.
A novel diagnostic has been developed that uses off-axis undulator radiation to characterize the longitudinal bunch profile of an electron beam. The diagnostic uses a small, ~0.1-m long undulator with mirrors that focus the undulator radiation onto an array of pyrometers. The mirrors both focus the radiation onto the pyrometer and remove the chirping effect that comes from the finite length of the undulator. Numerical and analytical models have been developed to calculate the radiation for a given bunch length, and a phase retrieval algorithm has been developed to extract the bunch profile from measured data. The diagnostic has been installed at the BELLA laser-plasma wakefield accelerator, and will be used to characterize the bunch length there. The concept and relevant results will be presented.

Slides WEZD4 [3.577 MB]

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEZD5

Micro-Electromechanical Systems Based Multi-Beam Ion Accelerators

Q. Ji, A. Amsellem, A. Persaud, Z. Qin, T. Schenkel, P.A. Seidl, N. Valverde
LBNL, Berkeley, California, USA
K. Afridi, V. Gund, Y. Hou, A. Lal, D. Ni
Cornell University, Ithaca, New York, USA
S.M. Lund
FRIB, East Lansing, Michigan, USA

Funding: This work was funded by ARPA-E. Work at LBNL was conducted under DOE Contract DE-AC0205CH11231. Device fabrication at the Cornell Nano Fabrication facility is supported by NSF Grant No. ECCS-1542081.
We report on the development of multi-beam radio frequency (RF) linear ion accelerators that are formed from stacks of low-cost printed circuit boards. An array of 112 beamlets is formed using MEMS techniques in 4" wafers. The peak argon ion current accelerated in the 112-beamlet column to date is 0.5 mA [1]. We have accelerated ions in stacks of 32 wafers to an energy of 100 keV. The measured energy gain in each RF gap reached 6.5 keV on average, resulting in an effective acceleration gradient of 0.4 MV/m. We will describe how this approach to multi-beam RF ion acceleration can scale to high beam power for applications in material processing and nuclear materials development.
[1] Qing Ji, et al., "Beam power scale-up in micro-electromechanical systems based multi-beam ion accelerators", Rev. Sci. Instr. 92, 103301 (2021); https://doi.org/10.1063/5.0058175

Slides WEZD5 [4.575 MB]

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEZD6

Manufacturing the Harmonic Kicker Cavity Prototype for the Electron-Ion Collider

601

S.A. Overstreet, M.W. Bruker, G.A. Grose, J. Guo, J. Henry, G.-T. Park, R.A. Rimmer, H. Wang, R.S. Williams
JLab, Newport News, Virginia, USA

Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177
High-bunch-frequency beam-separation schemes, such as the injection scheme proposed for the Rapid Cycling Synchrotron at the Electron-Ion Collider, demand rise and fall times an order of magnitude below what can realistically be accomplished with a stripline kicker. Nanosecond-time-scale kick waveforms can instead be obtained by Fourier synthesis in a harmonically resonant quarter-wave radio-frequency cavity which is optimized for high shunt impedance. Originally developed for the Jefferson Lab Electron-Ion Collider (JLEIC) Circulator Cooler Ring, a hypothetical 11-pass ring driven by an energy-recovery linac at Jefferson Lab, our high-power prototype of such a harmonic kicker cavity, which operates at five modes at the same time, will demonstrate the viability of this concept with a beam test at Jefferson Lab. As the geometry of the cavity, tight mechanical tolerances, and number of ports complicate the design and manufacturing process, special care must be given to the order of the manufacturing steps. We present our experiences with the manufacturability of the present design, lessons learned, and first RF test results from the prototype.

Slides WEZD6 [12.312 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEZD6

About •

Received ※ 04 August 2022 — Revised ※ 05 August 2022 — Accepted ※ 18 August 2022 — Issue date ※ 31 August 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPA12

Operational Experience of the New Booster Cryomodule at the Upgraded Injector Test Facility

640

M.W. Bruker, R. Bachimanchi, J.M. Grames, M.D. McCaughan, J. Musson, P.D. Owen, T.E. Plawski, M. Poelker, T. Powers, H. Wang, Y.W. Wang
JLab, Newport News, Virginia, USA

Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177.
Since the early 1990s, the injector of the CEBAF accelerator at Jefferson Lab has relied on a normal-conducting RF graded-beta capture section to boost the kinetic energy of the electron beam from 100 / 130 keV to 600 keV for subsequent acceleration using a cryomodule housing two superconducting 5-cell cavities similar to those used throughout the accelerator. To simplify the injector design and improve the beam quality, the normal-conducting RF capture section and the cryomodule will be replaced with a new single booster cryomodule employing a superconducting, β = 0.6, 2-cell-cavity capture section and a single, β = 0.97, 7-cell cavity. The Upgraded Injector Test Facility at Jefferson Lab is currently hosting the new cryomodule to evaluate its performance with beam before installation at CEBAF. While demonstrating satisfactory performance of the booster and good agreement with simulations, our beam test results also speak to limitations of accelerator operations in a noisy, thermally unregulated environment.

Poster WEPA12 [3.726 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA12

About •

Received ※ 03 August 2022 — Revised ※ 07 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 06 September 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPA16

A 500 kV Inverted Geometry Feedthrough for a High Voltage DC Electron Gun

651

C. Hernandez-Garcia, D.B. Bullard, J.M. Grames, G.G. Palacios Serrano, M. Poelker
JLab, Newport News, Virginia, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177 and Office of Science Funding Opportunity LAB 20-2310 award PAMS-254442.
The Continuous Electron Beam Accelerator Facility injector at Jefferson Lab (JLab) utilizes an inverted-geometry ceramic insulator photogun operating at 130 kV direct current to generate spin-polarized electron beams for high-energy nuclear physics experiments. A second photogun delivers 180 keV beam for commissioning a SRF booster in a testbed accelerator, and a larger version delivers 300 keV magnetized beam in a test stand beam line. This contribution reports on the development of an unprecedented inverted-insulator with cable connector for reliably applying 500 kV DC to a future polarized beam photogun, to be designed for operating at 350 kV without field emission. Such a photogun design could then be used for generating a polarized electron beam to drive a spin-polarized positron source as a demonstrator for high energy nuclear physics at JLab. There are no commercial cable connectors that fit the large inverted insulators required for that voltage range. Our proposed concept is based on a modified epoxy receptacle with intervening SF6 layer and a test electrode in a vacuum vessel.

Poster WEPA16 [6.217 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA16

About •

Received ※ 03 August 2022 — Revised ※ 05 August 2022 — Accepted ※ 07 August 2022 — Issue date ※ 09 October 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPA19

HE Production Update at JLab - Introducing an Enhanced Nitrogen Purge for Clean String Assembly

659

P.D. Owen
JLab, Newport News, Virginia, USA

A major limitation to cryomodule performance is field emission caused by particulates within the superconducting cavities. To reduce contamination of the inner surfaces during assembly in a cleanroom, the whole string can be connected to a purge system, which maintains a constant overpressure of dry, clean nitrogen gas. Following successes of similar systems at XFEL and Fermilab, Jefferson Lab followed this example for the production of LCLS-II HE cryomodules. Implementing this system required new procedures, infrastructure, and hardware, as well as significant testing of the system before production began. This paper will summarize the implemented controls and procedures, including lessons learned from Fermilab, as well as the results of mock-up tests. Based on the latter, the system was used to assemble the first article string in April 2022, and was also used during a rework required due to issues with cold FPC ceramics two months later. The benefits of using a purge system with regards to procedure, time savings, and added flexibility for potential rework have already proven to provide a significant improvement for the production of LCLS-II-HE cryomodules at Jefferson Lab.

Poster WEPA19 [1.538 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA19

About •

Received ※ 02 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 21 August 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPA26

197 MHz Waveguide Loaded Crabbing Cavity Design for the Electron-Ion Collider

679

S.U. De Silva, J.R. Delayen
ODU, Norfolk, Virginia, USA
J. Guo, R.A. Rimmer
JLab, Newport News, Virginia, USA
Z. Li
SLAC, Menlo Park, California, USA
B.P. Xiao
BNL, Upton, New York, USA

The Electron-Ion Collider will require crabbing systems at both hadron and electron storage rings in order to reach the desired luminosity goal. The 197 MHz crab cavity system is one of the critical rf systems of the col-lider. The crab cavity, based on the rf-dipole design, ex-plores the option of waveguide load damping to suppress the higher order modes and meet the tight impedance specifications. The cavity is designed with compact dog-bone waveguides with transitions to rectangular wave-guides and waveguide loads. This paper presents the compact 197 MHz crab cavity design with waveguide damping and other ancillaries.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA26

About •

Received ※ 08 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 06 September 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPA27

Effect of Duration of 120 °C Baking on the Performance of Superconducting Radio Frequency Niobium Cavities

683

B.D. Khanal
ODU, Norfolk, Virginia, USA
P. Dhakal
JLab, Newport News, Virginia, USA

Over the last decade much attention was given in increasing the quality factor of superconducting radio frequency (SRF) cavities by impurity doping. Prior to the era of doping, the final cavity processing technique to achieve the high accelerating gradient includes the "in situ" low temperature baking of SRF cavities at temperature ~ 120°C for several hours. Here, we present the results of a series of measurements on 1.3 GHz TESLA shape single-cell cavities with successive low temperature baking at 120°C up to 96 hours. The experimental data were analyzed with available theory of superconductivity to elucidate the effect of the duration of low temperature baking on the superconducting properties of cavity materials as well as the RF performance. In addition, the RF loss related to the trapping of residual magnetic field refereed as flux trapping sensitivity was measured with respect to the duration of 120°C bake.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA27

About •

Received ※ 01 August 2022 — Revised ※ 07 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 19 August 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPA30

Nb₃Sn Coating of a 2.6 GHz SRF Cavity by Sputter Deposition Technique

691

M.S. Shakel, W. Cao, H. Elsayed-Ali, Md.N. Sayeed
ODU, Norfolk, Virginia, USA
G.V. Eremeev
Fermilab, Batavia, Illinois, USA
U. Pudasaini, A-M. Valente-Feliciano
JLab, Newport News, Virginia, USA

Funding: Supported by DOE, Office of Accelerator R&D and Production, Contact No. DE-SC0022284, with partial support by DOE, Office of Nuclear Physics DE-AC05-06OR23177, Early Career Award to G. Eremeev.
Nb₃Sn is of interest as a coating for SRF cavities due to its higher transition temperature Tc ~18.3 K and superheating field Hsh ~400 mT, both are twice that of Nb. Nb₃Sn coated cavities can achieve high-quality factors at 4 K and can replace the bulk Nb cavities operated at 2 K. A cylindrical magnetron sputtering system was built, commissioned, and used to deposit Nb₃Sn on the inner surface of a 2.6 GHz single-cell Nb cavity. With two identical cylindrical magnetrons, this system can coat a cavity with high symmetry and uniform thickness. Using Nb-Sn multilayer sequential sputtering followed by annealing at 950°C for 3 hours, polycrystalline Nb₃Sn films were first deposited at the equivalent positions of the cavity’s beam tubes and equator. The film’s composition, crystal structure, and morphology were characterized by energy dispersive spectroscopy, X-ray diffraction, and atomic force microscopy. The Tc of the films was measured by the four-point probe method and was 17.61 to 17.76 K. Based on these studies, ~1.2 micron thick Nb₃Sn was deposited inside a 2.6 GHz Nb cavity. We will discuss first results from samples and cavity coatings, and the status of the coating system.

Poster WEPA30 [1.769 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA30

About •

Received ※ 03 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 22 August 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPA31

Lower Temperature Annealing of Vapor Diffused Nb₃Sn for Accelerator Cavities

695

J.K. Tiskumara, J.R. Delayen
ODU, Norfolk, Virginia, USA
G.V. Eremeev
Fermilab, Batavia, Illinois, USA
U. Pudasaini
JLab, Newport News, Virginia, USA

Nb₃Sn is a next-generation superconducting material for the accelerator cavities with higher critical temperature and superheating field, both twice compared to Nb. It promises superior performance and higher operating temperature than Nb, resulting in significant cost reduction. So far, the Sn vapor diffusion method is the most preferred and successful technique to coat niobium cavities with Nb₃Sn. Although several post-coating techniques (chemical, electrochemical, mechanical) have been explored to improve the surface quality of the coated surface, an effective process has yet to be found. Since there are only a few studies on the post-coating heat treatment at lower temperatures, we annealed Nb₃Sn-coated samples at 800 C - 1000 C to study the effect of heat treatments on surface properties, primarily aimed at removing surface Sn residues. This paper discusses the systematic surface analysis of coated samples after annealing at temperatures between 850 C and 950 C.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA31

About •

Received ※ 02 August 2022 — Revised ※ 05 August 2022 — Accepted ※ 07 August 2022 — Issue date ※ 02 September 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPA32

Spallation Neutron Source Cryogenic Moderator System Helium Gas Analysis System

699

B. DeGraff, L. Pinion
ORNL RAD, Oak Ridge, Tennessee, USA
R. Armstrong, J. Denison, M.P. Howell, S.-H. Kim, D. Montierth
ORNL, Oak Ridge, Tennessee, USA
M.D. Williamson
LBNL, Berkeley, California, USA

Funding: This work was supported by SNS through UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE.
The Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL) operates the Cryogenic Moderator System (CMS). The CMS comprises a 20-K helium refrigerator and three helium to hydrogen heat exchangers in support of hydrogen cooled spallation moderation vessels. This system uses vessels filled with activated carbon as the final major component to remove oil vapor from the compressed helium in the cryogenic cold box. SNS uses a LINDE multi-component gas analyzer to detect the presence of contaminants in the warm helium flow upstream of the cold box including aerosolized oil vapor. The design challenges of installing and operating this analyzer on the CMS system due to normal system operating pressures will be discussed. The design, fabrication, installation, commissioning, and initial results of this system operation will be presented. Future upgrades to the analyzer system will also be discussed.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA32

About •

Received ※ 06 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 05 October 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPA33

Laser Stripping for 1.3 GeV H⁻ Beam at the SNS

702

T.V. Gorlov, A.V. Aleksandrov, S.M. Cousineau, Y. Liu, A.R. Oguz
ORNL, Oak Ridge, Tennessee, USA
M.J. Kay
UTK, Knoxville, Tennessee, USA
P.K. Saha
JAEA/J-PARC, Tokai-mura, Japan

Funding: This work has been authored by UT-Battelle, LLC, under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy.
A realistic full duty factor laser stripping charge exchange injection scheme for future 1.3 GeV beam at the SNS is considered. Different schemes of laser stripping involving combinations of photoexcitation, photoionization and magnetic field stripping are calculated. The laser power and magnetic field strength needed for different approaches are estimated and compared. The most practical scheme of laser stripping is selected for development.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA33

About •

Received ※ 29 July 2022 — Revised ※ 05 August 2022 — Accepted ※ 09 August 2022 — Issue date ※ 23 August 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPA37

Benchmarking and Exploring Parameter Space of the 2-Phase Bubble Tracking Model for Liquid Mercury Target Simulation

711

L. Lin, M.I. Radaideh, H. Tran, D.E. Winder
ORNL, Oak Ridge, Tennessee, USA

Funding: This project was funded by the U.S. DOE under grant DE-SC0009915.
High intensity proton pulses strike the Spallation Neutron Source (SNS)’s mercury target to provide bright neutron beams. These strikes deposit extensive energy into the mercury and its steel vessel. Prediction of the resultant loading on the target is difficult when helium gas is intentionally injected into the mercury to reduce the loading and to mitigate the pitting damage on the vessel. A 2-phase material model that incorporates the Rayleigh-Plesset (R-P) model is expected to address this complex multi-physics dynamics problem by including the bubble dynamics in the liquid mercury. We present a study comparing the measured target strains in the SNS target station with the simulation results of the solid mechanics simulation framework. We investigate a wide range of various physical model parameters, including the number of bubble families, bubble size distribution, viscosity, surface tension, etc. to understand their impact on simulation accuracy. Our initial findings reveal that using 8-10 bubble families in the model renders a simulation strain envelope that covers the experimental ones. Further optimization studies are planned to predict the strain response more accurately.

Poster WEPA37 [1.985 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA37

About •

Received ※ 27 July 2022 — Revised ※ 08 August 2022 — Accepted ※ 12 August 2022 — Issue date ※ 01 September 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPA48

Electromagnetic Design of a Compact RF Chopper for Heavy-Ion Beam Separation at FRIB

738

A.C. Araujo Martinez, R.B. Agustsson, Y.C. Chen, S.V. Kutsaev
RadiaBeam, Santa Monica, California, USA
A.S. Plastun, X. Rao
FRIB, East Lansing, Michigan, USA

Funding: This work was supported by the U.S. Department of Energy, Office of High Energy Physics, under SBIR grant DE- SC0020671.
Rare isotope beams are produced at FRIB via fragmentation of a primary heavy ion beam in a thin target. The isotope beam of interest is contaminated with other fragments, which must be filtered out to ensure the delivery of rare isotopes with desired rates and purities. One of the stages of fragment separation uses an RF deflecting cavity to provide time-of-flight separation. However, to avoid neighboring bunches overlapping with each other and with the contaminants, it is necessary to increase the inter-bunch distance by a factor of four, corresponding to a 20.125 MHz rate. To solve this problem, we have developed an RF chopper system for the 500 keV/u primary heavy-ion beams. The system consists of a deflecting quarter wave resonator (QWR) cavity operating at 60.375 MHz, two dipole steering magnets, and a beam dump. In this paper, we present and discuss the optimization of the electromagnetic design of the QWR cavity and magnets, as well as some aspects, related to beam dynamics and conceptual engineering design.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA48

About •

Received ※ 02 August 2022 — Revised ※ 05 August 2022 — Accepted ※ 06 August 2022 — Issue date ※ 08 September 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPA49

Ferrite-Free Circulator for Precise Measurements of SRF Cavities with High Q-Factor

742

A.I. Pronikov, A.Yu. Smirnov
RadiaBeam, Santa Monica, California, USA
A.A. Krasnok
Florida International University, Miami, Florida, USA
S.N. Romanenko
Zaporizhzhya National Technical University, Zaporizhzhya, Ukraine
V.P. Yakovlev
Fermilab, Batavia, Illinois, USA

Funding: This work was supported by the US Department of Energy, Offices of High Energy and Nuclear Physics, awards DE-SC0020926 and DE-SC0022439.
In this work, we suggest and investigate new magnetless circulators based on three resonators connected in a loop and parametrically modulated in time with mutual phase lag. The first design consists of three Fano resonators with a spectrally asymmetric response, in contrast to schemes based on the Lorentz resonators explored thus far. The second design includes three Fano-Lorentz resonators, i.e., it also possesses spatial asymmetry. We demonstrate that the asymmetric approach provides strong and reversible isolation for the practically feasible modulation amplitude and rate. The results of our work are promising for precise measurements of superconducting radio frequency cavities with high Q-factor.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA49

About •

Received ※ 04 August 2022 — Revised ※ 07 August 2022 — Accepted ※ 09 August 2022 — Issue date ※ 13 September 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPA50

Initial Development of a High-Voltage Pulse Generator for a Short-Pulse Kicker

745

J. Prager, K.E. Miller, K. Muggli, C. Schmidt, H. Yeager
EHT, Seattle, Washington, USA

Funding: This work was funded by a DOE SBIR (DE-SC0021470).
The future Electron Ion Collider, to be located at Brookhaven National Laboratory (BNL), will require a new short-pulse stripline kicker for the 150 MeV energy recovery LINAC. The pulse generator must produce ±50 kV pulses with widths less than 38 ns into a 50° kicker load and with low jitter. The power system must be highly reliable and robust to potential faults. Eagle Harbor Technologies (EHT), Inc. is leveraging our previous experience developing inductive adders to produce a high-voltage pulse generator that can meet the needs of the BNL kickers. In this program, EHT designed a single inductive adder stage and demonstrated the challenging pulse characteristics including fast rise and fall times, low jitter, and flattop stability while operating at the full current (1 kA). EHT will present the development status and output waveforms.

Poster WEPA50 [1.118 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA50

About •

Received ※ 01 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 12 August 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPA52

Demonstration of Twice-Reduced Lorentz-Force Detuning in SRF Cavity by Copper Cold Spraying

749

R.A. Kostin, C.-J. Jing, A. Kanareykin
Euclid TechLabs, Solon, Ohio, USA
G. Ciovati
JLab, Newport News, Virginia, USA

Funding: The project is funded by DOE SBIR # DE-SC0019589
Superconducting RF (SRF) cavities usually are made from thin-walled high RRR Niobium and are susceptible to Lorentz Force Detuning (LFD) ’ cavity deformation phenomena by RF fields. In this paper, we present high gradient cryogenic results of an SRF cavity with two times reduced LFD achieved by copper cold spray reinforcement without sacrificing cavity flexibility for tuning. Finite-element model was developed first to find the best geometry for LFD reduction, which incorporated coupled RF, structural and thermal modules, and is also presented.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA52

About •

Received ※ 27 July 2022 — Revised ※ 03 August 2022 — Accepted ※ 09 August 2022 — Issue date ※ 16 August 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPA53

An Open Radiofrequency Accelerating Structure

753

S.V. Kuzikov
Euclid TechLabs, Solon, Ohio, USA

We report an open multi-cell accelerating structure. Being integrated with a set of open-end waveguides, this structure can suppress high-order modes (HOMs). All the accelerating cells are connected at the side to rectangular cross-section waveguides which strongly coupled with free space or absorbers. Due to the anti-phased contribution of the cell pairs, the operating mode does not leak out, and has as high-quality factor as for a closed accelerating structure. However, the compensation does not occur for spurious high-order modes. This operating principle also allows for strong coupling between the cells of the structure, which is why high homogeneity of the accelerating fields can be provided along the structure. We discuss the obtained simulation results and possible applications. Its include a normal conducting high-shunt impedance accelerator, a tunable photoinjector’s RF gun, and a high-current, high-selective SRF accelerators.

Poster WEPA53 [1.817 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA53

About •

Received ※ 01 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 12 August 2022 — Issue date ※ 16 August 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPA55

Applications of Machine Automation with Robotics and Computer Vision in Cleanroom Assemblies

756

A. Liu, J.R. Callahan, E. Gomez, S.M. Milller, W. Si
Euclid TechLabs, Solon, Ohio, USA

Funding: This work is supported by the US DOE SBIR program under contract number DE-SC0021736.
Modern linear particle accelerators use superconducting radio frequency (SRF) cavities for achieving extremely high-quality factors (Q) and higher beam stability. The assembly process of the system, although with a much more stringent cleanness requirement, is very similar to the ultrahigh vacuum (UHV) system operation procedure. Humans, who are conventionally the operators in this procedure, can only avoid contaminating the system by wearing proper sterile personal protection equipment to avoid direct skin contact with the systems, or dropping particulates. However, humans unavoidably make unintentional mistakes that can contaminate the environment: cross contamination of the coverall suits during wearing, slippage of masks or goggles, damaged gloves, and so forth. Besides, humans are limited when operating heavy weights, which may lead to incorrect procedures, or even worse, injury. In this paper, we present our recent work on a viable and cost-effective machine automation system composed of a robotic arm and a computer vision system for the assembly process in a cleanroom environment, for example for SRF string assemblies, and more.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA55

About •

Received ※ 30 July 2022 — Revised ※ 04 August 2022 — Accepted ※ 06 August 2022 — Issue date ※ 12 August 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPA56

Encapsulation of Photocathodes Using High Power Pulsed RF Sputtering of hBN

760

A. Liu, J.R. Callahan, S. Poddar
Euclid TechLabs, Solon, Ohio, USA
J.P. Biswas, M. Gaowei
BNL, Upton, New York, USA

Funding: This work is supported by the US DOE SBIR program under contract number DE-SC0021511 and DE-SC0020573.
Photocathodes of various materials are used in photoinjectors for generating photoelectron beams. Of particular interest are the alkali antimonides because of their ultra-high quantum efficiency (QE) and relatively low requirements for growth, and metallic materials such as Cu and Mg which have lower QE but are easier to maintain and have longer lifetime. The biggest challenge of using the alkali antimonide photocathode is that it has an extremely stringent requirement on vacuum and is destroyed rapidly by residual air in the system, while exposure of Mg and Cu in air also impacts the photocathode performance because of the oxidation. The photocathode can be protected against harmful gas molecules by using one or two monolayers of a 2D material such as graphene or hexagonal boron nitride (hBN). Furthermore, hBN monolayers even have the potential to improve the QE of the photocathode when working as the encapsulation thin-film. In this paper, we will discuss the feasibility of coating a photocathode with hBN by high power pulsed RF sputtering by using metallic photocathodes as examples, and compare the performance with encapsulated photocathodes with transferred hBN thin-films.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA56

About •

Received ※ 31 July 2022 — Revised ※ 04 August 2022 — Accepted ※ 08 August 2022 — Issue date ※ 10 August 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPA63

Extensions of the Complex (IQ) Baseband RF Cavity Model Including RF Source and Beam Interactions

767

S.P. Jachim, B.J. Cook, J.R.S. Falconer
Arizona State University, Tempe, USA

Funding: This work was supported in part by NSF award #1935994.
This paper extends prior work describing a complex envelope (i.e., baseband) dynamic model of excited accelerator RF cavities, including the effects of frequency detuning, beam loading, reflections, multiple drive ports, and parasitic modes. This model is presented here in closed-form transfer function and state-variable realizations, which may be more appropriate for analytic purposes. Several example simulations illustrate the detailed insight into RF system behavior afforded by this model.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA63

About •

Received ※ 28 July 2022 — Revised ※ 08 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 15 August 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPA64

Design and Commissioning of the ASU CXLS Machine Protection System

770

S.P. Jachim, B.J. Cook, J.R.S. Falconer, A.J. Gardeck, W.S. Graves, M.R. Holl, R.S. Rednour, D.M. Smith, J.V. Vela
Arizona State University, Tempe, USA

Funding: This work was supported in part by NSF award #1935994.
To protect against fault conditions in the high-power RF transport and accelerating structures of the Arizona State University (ASU) Compact X-Ray Light Source (CXLS), the Machine Protection System (MPS) extinguishes the 6.5-MW RF energy sources within approximately 50 ns of the fault event. In addition, each fault is localized and reported remotely via USB for operational and maintenance purposes. This paper outlines the requirements, design, and performance of the MPS applied on the CXLS.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA64

About •

Received ※ 13 July 2022 — Revised ※ 28 July 2022 — Accepted ※ 08 August 2022 — Issue date ※ 12 August 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPA77

A New PCB Rotating Coil at NSLS-II

816

M. Musardo, J. Avronsart, F.A. DePaola, L. Doom, R. Faussete, F.C. Lincoln, S.K. Sharma, T. Tanabe
BNL, Upton, New York, USA
D. Assell, J. DiMarco
Fermilab, Batavia, Illinois, USA
A. Banerjee
SBU, Stony Brook, New York, USA
C.L. Doose, A.K. Jain
ANL, Lemont, Illinois, USA

Several R&D projects are underway at NSLS-II towards an upgrade of its storage ring with a new lattice that will use high field magnets with small bores of 16-22 mm. A large fraction of the high field magnets are expected to be of permanent magnet technology that will require precise magnetic measurements and field harmonics corrections. A new magnetic measurement bench has been built based on a printed circuit board (PCB) coil of 12 mm diameter and 270 mm active length. This PCB coil has the capabil-ity of measuring field quality to a level of 10 ppm of the main field up to the 15th harmonic with a sensitivity between 0.01 m2 and 0.02 m2 at the reference radius of 5 mm. This paper will describe the main features of the rotating coil bench and discuss the measurement results of a permanent-magnet Halbach quadrupole of 12.7 mm bore diameter.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA77

About •

Received ※ 28 July 2022 — Revised ※ 06 August 2022 — Accepted ※ 12 August 2022 — Issue date ※ 29 August 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEADE1

Integrating Diversity and Inclusion in the Workplace: Los Alamos National Laboratory’s Strategies for Expanding Diversity and Fostering Inclusion and Belonging

K.S. Haight
LANL, Los Alamos, New Mexico, USA

Diversity fuels an innovative, agile and principled workforce that is essential to solving problems of global importance. Diversity of thought, experience, and perspective leads to better problem solving and promotes creativity. But diversity in the workplace does not organically grow without conscientious attention. Like growing a tree requires water, sun and fresh air, growing a diverse workforce requires awareness, strategy and reflection. Los Alamos National Laboratory’s approach to expanding diversity employs awareness, strategic action-oriented programs, and consistent reflection and rerouting to build a workforce that reflects the nation and world we are tasked to protect. But expanding diversity is meaningless without also fostering inclusion and belonging. Hear about successes and areas for further redirection from Los Alamos’s EEO and Affirmative Action Officer. Hear about the diversity of our Accelerator community and how this sector of our workforce compares to the broader community. And hear how the voices of our workforce are shaping our programs and initiatives to ensure that every unique voice, every idea and opinion, are welcome and respected.

Slides WEADE1 [1.698 MB]

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THYE1

Overview of Superconducting Magnet Technologies

S.O. Prestemon
LBNL, Berkeley, California, USA

Very high field superconducting magnets represent a critical technology for future accelerators, high field user magnets, and energy applications such as magnetic fusion and wind turbines. We discuss exciting technical developments in the field and the national and international communities efforts to organize R&D to advance the field.

Slides THYE1 [12.687 MB]

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THYE2

Development of Short-Period Nb₃Sn Superconducting Planar Undulators at the Advanced Photon Source

I. Kesgin
ANL, Lemont, Illinois, USA

Superconducting technology has enabled the development of short-period undulators for higher-brightness X-rays at synchrotron light sources. Superconducting undulators (SCUs) hold great promise for XFELs as well. All operational devices are currently Nb Ti-based. Nb₃Sn has the potential to further enhance the performance of SCUs. This paper will describe the technical challenges and progress to date of this technology.

Slides THYE2 [2.436 MB]

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THYE3

Superconducting Undulators and Cryomodules for X-ray Free-Electron Lasers

870

D.C. Nguyen, G.J. Bouchard, B.M. Dunham, G.L. Gassner, Z. Huang, E.M. Kraft, P. Krejcik, M.A. Montironi, H.-D. Nuhn, T.O. Raubenheimer, Z.R. Wolf, Z. Zhang
SLAC, Menlo Park, California, USA
J.M. Byrd, J.D. Fuerst, E. Gluskin, Y. Ivanyushenkov, M. Kasa, E.R. Moog, M.F. Qian, Y. Shiroyanagi
ANL, Lemont, Illinois, USA

Funding: Work supported by the US DOE Office of Science, Basic Energy Sciences, Office of Accelerator and Detector Research (Manager: Dr. Eliane Lessner).
We present connectable designs of superconducting undulators (SCU) and cryomodules (CM) based on previous SCU and CM designs at Argonne National Lab. The new SCU and CM designs will allow us to connect one CM to the next to form a contiguous line of SCUs with no breaks between the cryomodules. The SCU design will have correctors and phase shifters integrated into the main SCU magnet core, as well as external corrector magnets for trajectory corrections. There will also be a cryogenic magnetic quadrupole and a cold RF beam position monitor (BPM) integrated in the SCU CM. In addition to providing the usual FODO transverse focusing, the quadrupole and BPM will be used for the beam-based alignment technique that is critical for X-ray FEL operation. In this paper, we will present the conceptual design of the new SCU CM as well as results of FEL simulations using the SCUs as afterburners for the LCLS hard X-ray undulators.

Slides THYE3 [2.657 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-THYE3

About •

Received ※ 02 August 2022 — Revised ※ 07 August 2022 — Accepted ※ 08 August 2022 — Issue date ※ 16 August 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THYE4

Development of an Ultra-Low Vibration Cryostat Based on a Closed-Cycle Cryocooler

874

R.W. Roca
Illinois Institute of Technology, Chicago, Illinois, USA
E.W. Knight, R.A. Kostin, Y. Zhao
Euclid TechLabs, Solon, Ohio, USA

Low temperature and low vibration cryostats are useful in a variety of applications such as x-ray diffraction, quantum computing, x-ray monochromators and cryo-TEMs. In this project, we explore an ultra-low vibration cryostat with the cooling provided by a closed cycle cryocooler. Closed-cycle cryocoolers inevitably introduce vibrations into the system, and in this project, flexible copper braiding was used to decouple vibrations and provide cooling at the same time. In order to develop the cryostat, capacity map of a two stage Sumitomo cryocooler was measured as well as vibration transmission through different copper braids using an IR interferometer. This paper covers the capacity map and vibration measurements in the first prototype.

Slides THYE4 [4.989 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-THYE4

About •

Received ※ 16 July 2022 — Revised ※ 10 August 2022 — Accepted ※ 20 August 2022 — Issue date ※ 12 September 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THYE5

Analysis of Low RRR SRF Cavities

877

K. Howard, Y.K. Kim
University of Chicago, Chicago, Illinois, USA
D. Bafia, A. Grassellino
Fermilab, Batavia, Illinois, USA

Recent findings in the superconducting radio-frequency (SRF) community have shown that introducing certain impurities into high-purity niobium can improve quality factors and accelerating gradients. Success has been found in nitrogen-doping, diffusion of the native oxide into the niobium surface, and thin films of alternate superconductors atop a niobium bulk cavity. We question why some impurities improve RF performance while others hinder it. The purpose of this study is to characterize the impurity profile of niobium with a low residual resistance ratio (RRR) and correlate these impurities with the RF performance of low RRR cavities so that the mechanism of recent impurity-based improvements can be better understood and improved upon. Additionally, we performed surface treatments, low temperature baking and nitrogen-doping, on low RRR cavities to evaluate how the intentional addition of more impurities to the RF layer affects performance. We have found that low RRR cavities experience low temperature-dependent BCS resistance behavior more prominently than their high RRR counterparts. The results of this study have the potential to unlock a new understanding on SRF materials.

Slides THYE5 [5.013 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-THYE5

About •

Received ※ 03 August 2022 — Revised ※ 07 August 2022 — Accepted ※ 09 August 2022 — Issue date ※ 01 October 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THYE6

First Demonstration of a ZrNb Alloyed Surface for Superconducting Radio-Frequency Cavities

881

Z. Sun, M. Liepe, T.E. Oseroff
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Surface design of the RF surface is a promising path to next-generation SRF cavities. Here, we report a new strategy based on ZrNb surface alloying. Material development via an electrochemical process will be detailed. RF performance evaluated in the Cornell sample host cavity will be discussed. Cornell demonstrates that ZrNb alloying is a viable new technology to improve the performance of SRF cavities.

Slides THYE6 [1.459 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-THYE6

About •

Received ※ 22 July 2022 — Accepted ※ 08 August 2022 — Issue date ※ 20 August 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)