MAGNETIC HYGIENE CONTROL ON LCLS-II CRYOMODULES FABRICATED AT JLAB

Conference · Sun Dec 31 23:00:00 EST 2017

DOI:https://doi.org/10.18429/JACoW-SRF2017-MOPB044· OSTI ID:1985146

Cheng, Guangfeng ^[1]; Fischer, John ^[1]; Daly, Edward ^[1]; Davis, Giles ^[1]; Huque, Naeem ^[1]; Legg, Robert ^[1]; Park, HyeKyoung ^[1]; Wilson, Katherine ^[1]; Zhao, Liang ^[1]

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1. Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

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.

• Research Organization: Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Nuclear Physics (NP)
• DOE Contract Number: AC05-06OR23177
• OSTI ID: 1985146
• Report Number(s): JLAB-ACE-17-2518; DOE/OR/23177-4178
• Country of Publication: United States
• Language: English