Low Temperature Heat Treatment on the HWR Cavity

Institute for Basic Science have been constructing Superconducting LINAC composed of quarter wave resonator (QWR) and half wave resonator (HWR). All QWR cavities have been completely fabricated and successfully tested to be assembled in QWR cryomodules. For now, we have been testing HWR cavities over 50%. For the testing period, the success rate experienced up and downs like we went through during the QWR tests. In many cases, we observed that some cavities did not reach requirement performance 2K although they showed high performance at 4K. We increased the temperature of heat treatment to cure the rapid Q drop at the high gradient and observed most cavities passed the test after heat treatment.
Proceedings of the 20th International Conference on RF Superconductivity, SRF2021, East Lansing, MI, USA