超伝導加速空洞の高電界化に向けた研究（その1）

抄録

High gradient effort on 1.3 GHz superconducting cavity of single cell and 9-cell was started around 20 years ago. Many efforts and developments have been made and the TESLA technology became a baseline of cavity fabrication and surface treatment of XFEL cavity and ILC cavity. However, ILC goal which is 35 MV/m@Q0=8E9 with 90% yield is a little beyond of the present status. Continuous effort for high gradient with high yield has been made to reach ILC specification. The opportunity of the construction of surface treatment facility at KEK-STF advances the research of the cavity high gradient. The optimization of the electro-chemical facility by the chemical analysis, surface analysis and the coupon experiments has been done. The optical observation of the cavity inner surface together with quench localization technique suggests that some defect is responsible for quench at low gradient. The electromagnetic calculation and defect removal tool suggests the understanding of defect and its solution. This paper covers the topics that are now under research and in progress at KEK-STF.