SRF2017 - List of Authors (Park, H.)

Paper	Title	Page
MOPB044	Magnetic Hygiene Control on LCLS-II Cryomodules Fabricated at JLab	153
	G. Cheng, E. Daly, G.K. Davis, J.F. Fischer, N.A. Huque, R.A. Legg, H. Park, K.M. Wilson, L. Zhao JLab, Newport News, Virginia, USA
	Funding: U.S. DOE Contract No. DE-AC05-06OR23177 and the LCLS-II project. Jefferson Lab (JLab) is in collaboration with Fermi Na-tional Accelerator Laboratory (Fermilab) to build 18 cryomodules to install at the SLAC National Accelerator Laboratory's tunnel as part of the Linac Coherent Light Source upgrade project (LCLS-II). Each LCLS-II cry-omodule hosts 8 superconducting niobium cavities that adopt the nitrogen doping technique, which aims to en-hance the cavity quality factor Qo to reduce the consumption of liquid helium used to cool down the cavities. It is known that the Qo of niobium cavities is affected by cavity surface magnetic field. Traditionally, magnetic shields made of high magnetic permeability mu-metals are employed as a passive shielding of the ambient magnetic fluxes. During the LCLS-II cryomodule development, magnetic hygiene control that includes magnetic shielding and demagnetization of parts and the whole-machine is implemented. JLab and Fermilab worked closely on developing magnetic hygiene control procedures, identifying relevant tools, investigating causes of magnetization, magnetic field monitoring, etc. This paper focuses on JLab's experiences with LCLS-II cryomodule magnetic hygiene control during its fabrication. Authored by Jefferson Science Associates, LLC. The U.S. Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce this manuscript for Government purposes.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB044
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TUPB053	Lessons Learned from RF-Dipole Prototype Cavities for LHC High Luminosity Upgrade	506
	S.U. De Silva, J.R. Delayen ODU, Norfolk, Virginia, USA Z. Li SLAC, Menlo Park, California, USA H. Park JLab, Newport News, Virginia, USA
	The rf-dipole cavity has successfully demonstrated the principles of using a compact cavity operating in TE11-like mode in generating a transverse kick. Several proof-of-principle rf-dipole cavities have been fabricated and the rf tests have demonstrated high transverse gradients. The rf-dipole geometry has been adapted into a square-shaped geometry designed to meet the dimensional constraints for the LHC also maintaining crabbing in both horizontal and vertical planes. Recently, two prototype rf-dipole cavities intended for the test at SPS for have been completed that is designed to accommodate the FPC and HOM dampers. The performance during the rf tests have shown excellent results on achieving the design requirements of operation for the crab cavities for SPS. This paper presents the experiences and lessons learned during the cavity preparation and testing, including process validation, frequency tracking.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB053
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TUPB054	RF Tests of RF-Dipole Prototype Crabbing Cavities for LHC High Luminosity Upgrade	509
	S.U. De Silva, J.R. Delayen ODU, Norfolk, Virginia, USA Z. Li SLAC, Menlo Park, California, USA H. Park JLab, Newport News, Virginia, USA
	The superconducting rf-dipole crabbing cavity is one of the two crabbing cavity designs proposed for the LHC high luminosity upgrade. The proof-of-principle (P-o-P) rf-dipole cavity operating at 400 MHz has demonstrated performance exceeding the design specifications. The prototype cavity for SPS beam test has been designed to include the fundamental power coupler, HOM couplers, and all the ancillary components intended to meet the design requirements. The crab cavities will be installed in the SPS beam line prior to the installation in LHC; this will be the first crabbing cavity operation on a proton beam. The fabrication of two prototype rf-dipole cavities is currently being completed at Jefferson Lab. This paper presents the details on cavity processing and cryogenic test results of the rf-dipole cavities.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB054
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WEYA06	Superconducting Twin-axis Cavity for ERL Applications
	H. Park, S.U. De Silva, J.R. Delayen, L. Sweat ODU, Norfolk, Virginia, USA J.R. Delayen, A. Hutton, F. Marhauser, H. Park JLab, Newport News, Virginia, USA
	The elliptical twin-axis cavity is a new kind of superconducting cavity that consists of two parallel beam pipes, which can accelerate or decelerate two beams in two separate beam pipes. The new cavity geometry is intended to create a uniform accelerating or decelerating fields for both beams. The twin-axis cavity can offer advantages in low-energy ERL applications by allowing increased bunch charge while preserving emittance. A 1.5 GHz superconducting twin-axis cavity has been designed, developed, fabricated, and tested. Experimental results will be presented.
	Slides WEYA06 [7.061 MB]
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THPB080	Measurement of Frequency, Temperature, RF Field Dependent Surface Resistance Using Superconducting Half Wave Cavity	925
	H. Park JLab, Newport News, Virginia, USA S.U. De Silva, J.R. Delayen, H. Park ODU, Norfolk, Virginia, USA
	A theory of surface resistance of superconductor was rigorously formulated by Bardeen, Cooper, Schrieffer more than 50 years ago. Since then the accelerator community has been used the theory as a guideline to improve the surface resistance of the superconducting cavity. It has been observed that the surface resistance is dependent on frequency, temperature and rf field strength, and surface preparation. To verify these dependences, a well-controlled study is required. Although many different types of cavities have been tested, the typical superconducting cavities are built for specific frequencies of their application. They do not provide data other than at its own frequency. A superconducting half wave cavity is a cavity that enables us to collect the surface resistance data across frequencies of interest for particle accelerators and evaluate preparation techniques. This paper will present the design of the half wave cavity, its electromagnetic mode characteristics and experimental results.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-THPB080
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Paper

Title

Page

Magnetic Hygiene Control on LCLS-II Cryomodules Fabricated at JLab

153

G. Cheng, E. Daly, G.K. Davis, J.F. Fischer, N.A. Huque, R.A. Legg, H. Park, K.M. Wilson, L. Zhao
JLab, Newport News, Virginia, USA

Funding: U.S. DOE Contract No. DE-AC05-06OR23177 and the LCLS-II project.
Jefferson Lab (JLab) is in collaboration with Fermi Na-tional Accelerator Laboratory (Fermilab) to build 18 cryomodules to install at the SLAC National Accelerator Laboratory's tunnel as part of the Linac Coherent Light Source upgrade project (LCLS-II). Each LCLS-II cry-omodule hosts 8 superconducting niobium cavities that adopt the nitrogen doping technique, which aims to en-hance the cavity quality factor Qo to reduce the consumption of liquid helium used to cool down the cavities. It is known that the Qo of niobium cavities is affected by cavity surface magnetic field. Traditionally, magnetic shields made of high magnetic permeability mu-metals are employed as a passive shielding of the ambient magnetic fluxes. During the LCLS-II cryomodule development, magnetic hygiene control that includes magnetic shielding and demagnetization of parts and the whole-machine is implemented. JLab and Fermilab worked closely on developing magnetic hygiene control procedures, identifying relevant tools, investigating causes of magnetization, magnetic field monitoring, etc. This paper focuses on JLab's experiences with LCLS-II cryomodule magnetic hygiene control during its fabrication.
Authored by Jefferson Science Associates, LLC. The U.S. Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce this manuscript for Government purposes.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB044

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TUPB053

Lessons Learned from RF-Dipole Prototype Cavities for LHC High Luminosity Upgrade

506

S.U. De Silva, J.R. Delayen
ODU, Norfolk, Virginia, USA
Z. Li
SLAC, Menlo Park, California, USA
H. Park
JLab, Newport News, Virginia, USA

The rf-dipole cavity has successfully demonstrated the principles of using a compact cavity operating in TE11-like mode in generating a transverse kick. Several proof-of-principle rf-dipole cavities have been fabricated and the rf tests have demonstrated high transverse gradients. The rf-dipole geometry has been adapted into a square-shaped geometry designed to meet the dimensional constraints for the LHC also maintaining crabbing in both horizontal and vertical planes. Recently, two prototype rf-dipole cavities intended for the test at SPS for have been completed that is designed to accommodate the FPC and HOM dampers. The performance during the rf tests have shown excellent results on achieving the design requirements of operation for the crab cavities for SPS. This paper presents the experiences and lessons learned during the cavity preparation and testing, including process validation, frequency tracking.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB053

Export •

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

TUPB054

RF Tests of RF-Dipole Prototype Crabbing Cavities for LHC High Luminosity Upgrade

509

S.U. De Silva, J.R. Delayen
ODU, Norfolk, Virginia, USA
Z. Li
SLAC, Menlo Park, California, USA
H. Park
JLab, Newport News, Virginia, USA

The superconducting rf-dipole crabbing cavity is one of the two crabbing cavity designs proposed for the LHC high luminosity upgrade. The proof-of-principle (P-o-P) rf-dipole cavity operating at 400 MHz has demonstrated performance exceeding the design specifications. The prototype cavity for SPS beam test has been designed to include the fundamental power coupler, HOM couplers, and all the ancillary components intended to meet the design requirements. The crab cavities will be installed in the SPS beam line prior to the installation in LHC; this will be the first crabbing cavity operation on a proton beam. The fabrication of two prototype rf-dipole cavities is currently being completed at Jefferson Lab. This paper presents the details on cavity processing and cryogenic test results of the rf-dipole cavities.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB054

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

WEYA06

Superconducting Twin-axis Cavity for ERL Applications

H. Park, S.U. De Silva, J.R. Delayen, L. Sweat
ODU, Norfolk, Virginia, USA
J.R. Delayen, A. Hutton, F. Marhauser, H. Park
JLab, Newport News, Virginia, USA

The elliptical twin-axis cavity is a new kind of superconducting cavity that consists of two parallel beam pipes, which can accelerate or decelerate two beams in two separate beam pipes. The new cavity geometry is intended to create a uniform accelerating or decelerating fields for both beams. The twin-axis cavity can offer advantages in low-energy ERL applications by allowing increased bunch charge while preserving emittance. A 1.5 GHz superconducting twin-axis cavity has been designed, developed, fabricated, and tested. Experimental results will be presented.

Slides WEYA06 [7.061 MB]

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

THPB080

Measurement of Frequency, Temperature, RF Field Dependent Surface Resistance Using Superconducting Half Wave Cavity

925

H. Park
JLab, Newport News, Virginia, USA
S.U. De Silva, J.R. Delayen, H. Park
ODU, Norfolk, Virginia, USA

A theory of surface resistance of superconductor was rigorously formulated by Bardeen, Cooper, Schrieffer more than 50 years ago. Since then the accelerator community has been used the theory as a guideline to improve the surface resistance of the superconducting cavity. It has been observed that the surface resistance is dependent on frequency, temperature and rf field strength, and surface preparation. To verify these dependences, a well-controlled study is required. Although many different types of cavities have been tested, the typical superconducting cavities are built for specific frequencies of their application. They do not provide data other than at its own frequency. A superconducting half wave cavity is a cavity that enables us to collect the surface resistance data across frequencies of interest for particle accelerators and evaluate preparation techniques. This paper will present the design of the half wave cavity, its electromagnetic mode characteristics and experimental results.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-THPB080

Export •

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