Medium-temperature furnace baking of 1.3 GHz 9-cell superconducting cavities at IHEP. (6th August 2021)

• Record Type: Journal Article
• Authors: He, Feisi; Pan, Weimin; Sha, Peng; Zhai, Jiyuan; Mi, Zhenghui; Dai, Xuwen; Jin, Song; Zhang, Zhanjun; Dong, Chao; Liu, Baiqi; Zhao, Hui; Ge, Rui; Zhao, Jianbing; Mu, Zhihui; Du, Lei; Sun, Liangrui; Zhang, Liang; Yang, Conglai; Zheng, Xiaobing
• Is Part Of: Superconductor science & technology. Volume 34:Number 9(2021)
• Publication Date: 2021-08-06
• Subjects: superconducting cavity -- quality factor -- gradient -- medium-temperature furnace baking -- vertical test; Superconductivity -- Periodicals; Superconductors -- Periodicals; 537.623
• DOI: 10.1088/1361-6668/ac1657
• Languages: English
• ISSNs: 0953-2048

Abstract

Abstract: Recently, heat treatment in the range of 250 °C–500 °C has been attempted with the aim of improving the quality factor ( Q ) of superconducting radio-frequency (SRF) cavities worldwide. Herein, medium-temperature (mid-T) furnace baking experiments were conducted at the Institute of High Energy Physics to obtain higher Q values. First, 1.3 GHz 1-cell cavities received mid-T furnace baking at different temperatures, resulting in not only the improvement of Q but also an anti- Q -slope behavior. Furthermore, mid-T furnace baking was applied to six 1.3 GHz 9-cell cavities, all of which indicated higher Q and anti- Q -slope behavior. The average Q was 3.8 × 10 10 at 16 MV m −1 . The maximum gradients of the 9-cell cavities were 22.7–26.5 MV m −1 . Finally, the mid-T furnace baked 1.3 GHz 9-cell cavities were welded with helium vessel, with no degradation in the vertical tests. In addition, the mid-T furnace baking process was simplified in comparison with European X-ray Free Electron Laser and Linear Coherent Light Source because of the cancellation of light electro-polishing. This simplification is beneficial in the mass production of SRF cavities with high Q, which are widely adopted in free electron lasers and high-energy colliders.