MICROPHONICS TESTING OF LCLS II CRYOMODULES AT JLAB

Conference · Thu Aug 01 00:00:00 EDT 2019

DOI:https://doi.org/10.18429/JACoW-SRF2019-TUP034· OSTI ID:1975495

Powers, Thomas ^[1]; Davis, K. ^[1]; Brock, N. ^[1]

---

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

Jefferson Lab is partnering with Fermilab to build 40 cryomodules for the LCLS II accelerator that will be installed at the Stanford Linear Accelerator (SLAC). The LCLS II cryomodule is an 8-seat CW cryomodule which operates at 1300 MHz and is based on the XFEL design. The cavities have design loaded-Q of 4×107, which means that it has a control bandwidth of 16 Hz. The JLab prototype cryomodule was instrumented with a series of 10 accelerometers, and impulse hammer response measurements were made while the cryomodule was being built and after it was installed in the JLAB cryomodule test facility. This was done so that we could better understand the shapes of the modes of the structure. These results were compared to impulse hammer testing from the outside of the cryomodule to individual cavity frequency shifts when the cryomodule was cold. Additionally, background microphonics and transfer function measurements were made on several other LCLS II cryomodules in the JLab cryomodule test facility (CMTF). The prototype cryomodule had excessive microphonics up to 100 Hz peak due to a thermo-acoustic oscillation in the cryogenic supply circuit. Design modifications were implemented and subsequently the cryomodules had microphonics on the order of 10 to 20 Hz.

• Research Organization: Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Nuclear Physics (NP)
• DOE Contract Number: AC05-06OR23177
• OSTI ID: 1975495
• Report Number(s): JLAB-ACC-19-3148; DOE/OR/23177-6246
• Resource Relation: Conference: SRF2019 - Proceedings, Dresden, Germany, June 30, 2019
• Country of Publication: United States
• Language: English