DUMBBELL FABRICATION AND TUNING OF THE IHEP LARGE GRAIN 9-CELL CAVITY

As the key component of the “IHEP 1.3 GHz SCRF Accelerating Unit and Horizontal Test Stand Project”, a low-loss shape bare tube 9-cell cavity using Ningxia large grain niobium is being fabricated at IHEP. This paper presents the fabrication procedure and frequency tuning method of the dumbbells of this cavity. Due to the special properties of the large grain material, several mechanical and RF problems were found and successfully solved. After equator welding, this cavity will be surface treated and tested late this year.