NAPAC2022 - List of Authors (Petersen, T.B.)

Paper	Title	Page
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)

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)

WEPA03	Status of the SLAC/MSU SRF Gun Development Project	623
	J.W. Lewellen, C. Adolphsen, R. Coy, L. Ge, F. Ji, M.J. Murphy, L. Xiao SLAC, Menlo Park, California, USA A. Arnold, S. Gatzmaga, P. Murcek, R. Xiang HZDR, Dresden, Germany Y. Choi, C. Compton, X.-J. Du, D.B. Greene, W. Hartung, S.H. Kim, T. Konomi, S.J. Miller, D.G. Morris, M.S. Patil, J.T. Popielarski, L. Popielarski, K. Saito, T. Xu FRIB, East Lansing, Michigan, USA M.P. Kelly, T.B. Petersen ANL, Lemont, Illinois, USA
	Funding: US Department of Energy. The LCLS-II-HE project at SLAC is intended to increase the photon energy reach of the LCLS-II FEL to at least 20 keV. In addition to upgrading the undulator system, and increasing the electron beam energy to 8 GeV, the project will also construct a low-emittance injector (LEI) in a new tunnel. To achieve the LEI emittance goals, a low-MTE photocathode will be required, as will on-cathode electric fields up to 50% higher than those achievable in the current LCLS-II photoinjector. The beam source for the LEI will be based around a superconducting quarterwave cavity resonant at 185.7 MHz. A prototype gun is currently being designed and fabricated at the Facility for Rare Isotope Beams (FRIB) at Michigan State University. This paper presents the performance goals for the new gun design, an overview of the prototype development effort, current status, and future plans including fabrication of a "production" gun for the LEI.
	Poster WEPA03 [4.510 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA03
About •	Received ※ 21 July 2022 — Revised ※ 28 July 2022 — Accepted ※ 08 August 2022 — Issue date ※ 11 August 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THZD2	Advances in the ATLAS Accelerator
	M.P. Kelly, C. Dickerson, B.M. Guilfoyle, M.R. Hendricks, M. Kedzie, T.B. Petersen, T. Reid ANL, Lemont, Illinois, USA
	Funding: DOE-NP The ATLAS Superconducting Linac at Argonne National Laboratory is a leading facility for nuclear reaction and structure studies, providing ion beams over the full mass range to a community of users from the US and abroad. The technology of ATLAS has been continuously upgraded since commissioning in 1978 and has remained at the forefront of superconducting linac development, especially for low-beta Linacs, for more than four decades. We present an overview of the present state ATLAS superconducting technology, the latest approaches for superconducting cavity cryomodules commissioned within the last 10 years and the outlook and potential impact of transformative new technologies to low-beta ion accelerators.
	Slides THZD2 [14.708 MB]
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Paper

Title

Page

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)

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)

WEPA03

Status of the SLAC/MSU SRF Gun Development Project

623

J.W. Lewellen, C. Adolphsen, R. Coy, L. Ge, F. Ji, M.J. Murphy, L. Xiao
SLAC, Menlo Park, California, USA
A. Arnold, S. Gatzmaga, P. Murcek, R. Xiang
HZDR, Dresden, Germany
Y. Choi, C. Compton, X.-J. Du, D.B. Greene, W. Hartung, S.H. Kim, T. Konomi, S.J. Miller, D.G. Morris, M.S. Patil, J.T. Popielarski, L. Popielarski, K. Saito, T. Xu
FRIB, East Lansing, Michigan, USA
M.P. Kelly, T.B. Petersen
ANL, Lemont, Illinois, USA

Funding: US Department of Energy.
The LCLS-II-HE project at SLAC is intended to increase the photon energy reach of the LCLS-II FEL to at least 20 keV. In addition to upgrading the undulator system, and increasing the electron beam energy to 8 GeV, the project will also construct a low-emittance injector (LEI) in a new tunnel. To achieve the LEI emittance goals, a low-MTE photocathode will be required, as will on-cathode electric fields up to 50% higher than those achievable in the current LCLS-II photoinjector. The beam source for the LEI will be based around a superconducting quarterwave cavity resonant at 185.7 MHz. A prototype gun is currently being designed and fabricated at the Facility for Rare Isotope Beams (FRIB) at Michigan State University. This paper presents the performance goals for the new gun design, an overview of the prototype development effort, current status, and future plans including fabrication of a "production" gun for the LEI.

Poster WEPA03 [4.510 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA03

About •

Received ※ 21 July 2022 — Revised ※ 28 July 2022 — Accepted ※ 08 August 2022 — Issue date ※ 11 August 2022

Cite •

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

THZD2

Advances in the ATLAS Accelerator

M.P. Kelly, C. Dickerson, B.M. Guilfoyle, M.R. Hendricks, M. Kedzie, T.B. Petersen, T. Reid
ANL, Lemont, Illinois, USA

Funding: DOE-NP
The ATLAS Superconducting Linac at Argonne National Laboratory is a leading facility for nuclear reaction and structure studies, providing ion beams over the full mass range to a community of users from the US and abroad. The technology of ATLAS has been continuously upgraded since commissioning in 1978 and has remained at the forefront of superconducting linac development, especially for low-beta Linacs, for more than four decades. We present an overview of the present state ATLAS superconducting technology, the latest approaches for superconducting cavity cryomodules commissioned within the last 10 years and the outlook and potential impact of transformative new technologies to low-beta ion accelerators.

Slides THZD2 [14.708 MB]

Cite •

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