NAPAC2022 - List of Keywords (LLRF)

Paper	Title	Other Keywords	Page
MOPA30	LCLS-II BCS Average Current Monitor	cavity, electron, hardware, MMI	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)

MOPA88	FRIB and UEM LLRF Controller Upgrade	controls, cavity, FPGA, operation	256
	S.R. Kunjir, E. Bernal, D.G. Morris, S. Zhao FRIB, East Lansing, Michigan, USA C.-Y. Ruan MSU, East Lansing, Michigan, USA
	Funding: Supported by the U.S. DOE Office of Science under Cooperative Agreement DE-SC0000661, the State of Michigan, Michigan State University and U.S. National Science Foundation grant DMR-1625181. The Facility for Rare Isotope Beams (FRIB) is developing a 644 MHz superconducting (SC) cavity for a future upgrade project. The current low level radio frequency (LLRF) controller at FRIB is not able to operate at 644 MHz. The Ultrafast Electron Microscope (UEM) laboratory within the Department of Physics at Michigan State University designed an LLRF controller based on analog RF components to operate a 1.013 GHz room temperature (RT) cavity. With requirements for improved stability, performance and user controls there was a need to upgrade the analog LLRF controller. The FRIB radio frequency (RF) group designed, developed and fabricated a new digital LLRF controller, with high-speed serial interface between system on chip field programmable gate array and fast data converters and capable of high frequency direct sampling, to meet the requirements of 644 MHz SC cavity and 1.013 GHz UEM RT cavity. This paper gives an overview of the upgraded digital LLRF controller, its features, improvements and preliminary test results.
	Poster MOPA88 [2.818 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA88
About •	Received ※ 01 August 2022 — Revised ※ 03 August 2022 — Accepted ※ 04 August 2022 — Issue date ※ 16 August 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPA43	Novel RF Phase Detector for Accelerator Applications	detector, controls, cavity, feedback	446
	J.M. Potter JP Accelerator Works, Los Alamos, New Mexico, USA
	A novel phase detector has been developed that is suitable for use in an rf phase locked loop for locking an rf source to an rf accelerator structure or phase locking the accelerator structure to a fixed or adjustable frequency rf source. It is also useful for fast phase feedback to control the phase of an accelerator rf field. The principle is applicable to a wide range of frequencies and amplitudes. The phase is uniquely and unambiguously determined over 360°, eliminating the need for external phase shifters or phase references. The operation of this phase detector is described in detail. An application is described that uses a DDS-based LLRF source as the rf input to a high-power rf system.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA43
About •	Received ※ 02 August 2022 — Revised ※ 04 August 2022 — Accepted ※ 05 August 2022 — Issue date ※ 06 October 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPA58	Iterative Tuning of the Beam Feedforward Controller for LANSCE LINAC Digital Low Level RF Control System	controls, beam-loading, cavity, neutron	475
	S. Kwon, A.T. Archuleta, L.J. Castellano, M.S. Prokop, C. Rose, P.A. Torrez, P. Van Rooy LANL, Los Alamos, New Mexico, USA
	Funding: USDOE This paper addresses an iterative particle beam phase and amplitude feedforward controller tuning method based on the gradient search approach. The method does not need an a priori plant model as it only needs data collected in previous experimental runs. The controller is implemented on a field programmable gate array (FPGA) equipped with a real-time operating system and a network connection. Data from each RF pulse is collected and sent via the network to the FPGA for processing. The controller tuning is performed between the RF pulses. Once the tuning is performed, the controller parameters are downloaded to the controller in the FPGA and new controller parameters are applied at the upcoming RF pulse
	Poster TUPA58 [0.998 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA58
About •	Received ※ 01 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 10 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	controls, DTL, cavity, MMI	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)

TUPA69	Improving Cavity Phase Measurements at Los Alamos Neutron Science Center	cavity, GUI, controls, neutron	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)

Paper

Title

Other Keywords

Page

MOPA30

LCLS-II BCS Average Current Monitor

cavity, electron, hardware, MMI

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)

MOPA88

FRIB and UEM LLRF Controller Upgrade

controls, cavity, FPGA, operation

256

S.R. Kunjir, E. Bernal, D.G. Morris, S. Zhao
FRIB, East Lansing, Michigan, USA
C.-Y. Ruan
MSU, East Lansing, Michigan, USA

Funding: Supported by the U.S. DOE Office of Science under Cooperative Agreement DE-SC0000661, the State of Michigan, Michigan State University and U.S. National Science Foundation grant DMR-1625181.
The Facility for Rare Isotope Beams (FRIB) is developing a 644 MHz superconducting (SC) cavity for a future upgrade project. The current low level radio frequency (LLRF) controller at FRIB is not able to operate at 644 MHz. The Ultrafast Electron Microscope (UEM) laboratory within the Department of Physics at Michigan State University designed an LLRF controller based on analog RF components to operate a 1.013 GHz room temperature (RT) cavity. With requirements for improved stability, performance and user controls there was a need to upgrade the analog LLRF controller. The FRIB radio frequency (RF) group designed, developed and fabricated a new digital LLRF controller, with high-speed serial interface between system on chip field programmable gate array and fast data converters and capable of high frequency direct sampling, to meet the requirements of 644 MHz SC cavity and 1.013 GHz UEM RT cavity. This paper gives an overview of the upgraded digital LLRF controller, its features, improvements and preliminary test results.

Poster MOPA88 [2.818 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA88

About •

Received ※ 01 August 2022 — Revised ※ 03 August 2022 — Accepted ※ 04 August 2022 — Issue date ※ 16 August 2022

Cite •

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

TUPA43

Novel RF Phase Detector for Accelerator Applications

detector, controls, cavity, feedback

446

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

A novel phase detector has been developed that is suitable for use in an rf phase locked loop for locking an rf source to an rf accelerator structure or phase locking the accelerator structure to a fixed or adjustable frequency rf source. It is also useful for fast phase feedback to control the phase of an accelerator rf field. The principle is applicable to a wide range of frequencies and amplitudes. The phase is uniquely and unambiguously determined over 360°, eliminating the need for external phase shifters or phase references. The operation of this phase detector is described in detail. An application is described that uses a DDS-based LLRF source as the rf input to a high-power rf system.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA43

About •

Received ※ 02 August 2022 — Revised ※ 04 August 2022 — Accepted ※ 05 August 2022 — Issue date ※ 06 October 2022

Cite •

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

TUPA58

Iterative Tuning of the Beam Feedforward Controller for LANSCE LINAC Digital Low Level RF Control System

controls, beam-loading, cavity, neutron

475

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

Funding: USDOE
This paper addresses an iterative particle beam phase and amplitude feedforward controller tuning method based on the gradient search approach. The method does not need an a priori plant model as it only needs data collected in previous experimental runs. The controller is implemented on a field programmable gate array (FPGA) equipped with a real-time operating system and a network connection. Data from each RF pulse is collected and sent via the network to the FPGA for processing. The controller tuning is performed between the RF pulses. Once the tuning is performed, the controller parameters are downloaded to the controller in the FPGA and new controller parameters are applied at the upcoming RF pulse

Poster TUPA58 [0.998 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA58

About •

Received ※ 01 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 10 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

controls, DTL, cavity, MMI

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)

TUPA69

Improving Cavity Phase Measurements at Los Alamos Neutron Science Center

cavity, GUI, controls, neutron

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)