JLAB, Newport News, Virginia, USA
PKU/IHIP, Beijing, People's Republic of China
Quench limits accelerating gradient in SRF cavities to a gradient lower than theoretically expected for superconducting niobium. Identification of the quenching site with thermometry and OST, optical inspection, and replica of the culprit is an ongoing effort at Jefferson Lab aimed at better understanding of this limiting phenomenon. In this contribution we present our finding with several SRF cavities that were limited by quench.
PKU/IHIP, Beijing, People's Republic of China
JLAB, Newport News, Virginia, USA
A computer program which was used to simulate and analyze the thermal behaviors of SRF cavities has been developed at Jefferson Lab using C++ code. This code was also used to verify the quench initiation due to geometrical defects in high magnetic field region of SRF cavities. We built a CEBAF single cell cavity with 4 artificial defects near equator, and this cavity has been tested with T-mapping. The preheating behavior and quench initiation analysis of this cavity will be presented here using the computer program.
daijin@pku.edu.cn
PKU/IHIP, Beijing, People's Republic of China
JLAB, Newport News, Virginia, USA
KEK, Ibaraki, Japan
Three kinds of geometrical features analysis techniques were adopted in association with cavity gradient R&D at Jefferson Lab: (1) Feature shape analysis by Kyoto camera system; (2) 3D shape analysis using a HIROX KH-7700 High Resolution Digital-Video Microscopy System; (3) Replica technique plus surface profiler for profile measurement of geometrical features. Up to now, many features were found in two nine cell SRF cavities: PKU2 from Peking University in China and NR1 from Niowave-Roark in America. Both of them have been RF tested at 2K. The shape analysis of geometrical surface features and correlation with RF test results using a thermal analysis code will be presented here.
daijin@pku.edu.cn