LCLS-II-HE verification cryomodule high gradient performance and quench behavior
Abstract
An 8-cavity, 1.3 GHz, LCLS-II-HE cryomodule was assembled and tested at Fermilab to verify performance before the start of production. Its cavities were processed with a novel nitrogen doping treatment to improve gradient performance. The cryomodule was tested with a modified protocol to process sporadic quenches, which were observed in LCLS-II production cryomodules and are attributed to multipacting. Dedicated vertical test experiments support the attribution to multipacting. The verification cryomodule achieved an acceleration voltage of 200 MV in continuous wave mode, corresponding to an average accelerating gradient of 24.1 MV/m, significantly exceeding the specification of 173 MV. The average Q0 (3.0x10^10) also exceeded its specification (2.7x10^10). After processing, no field emission was observed up to the maximum gradient of each cavity. This paper reviews the cryomodule performance and discusses operational issues and mitigations implemented during the several month program.
Keywords
Cite
@article{arxiv.2110.14580,
title = {LCLS-II-HE verification cryomodule high gradient performance and quench behavior},
author = {S. Posen and A. Cravatta and M. Checchin and S. Aderhold and C. Adolphsen and T. Arkan and D. Bafia and A. Benwell and D. Bice and B. Chase and C. Contreras-Martinez and L. Dootlittle and J. Fuerst and D. Gonnella and A. Grassellino and C. Grimm and B. Hansen and E. Harms and B. Hartsell and G. Hays and J. Holzbauer and S. Hoobler and J. Kaluzny and T. Khabiboulline and M. Kucera and D. Lambert and R. Legg and F. Lewis and J. Makara and H. Maniar and J. T. Maniscalco and M. Martinello and J. Nelson and S. Paiagua and Y. Pischalnikov and P. Prieto and J. Reid and M. Ross and C. Serrano and N. Solyak and A. Syed and D. Sun and G. Tatkowski and R. Wang and M. White and L. Zacarias},
journal= {arXiv preprint arXiv:2110.14580},
year = {2021}
}
Comments
15 pages, 24 figures