Achieving high gradient performance of 9-cell cavities at KEK for the international linear collider

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• 作者：Y. Yamamoto ; H. Hayano ; E. Kako ; S. Noguchi ; T. Shishido ; K. Watanabe
• 关键词：ILC ; Superconducting cavity ; Vertical test ; Local mechanical grinding ; Problematic defect ; Field emission
• 刊名：Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
• 出版年：2013
• 出版时间：21 November, 2013
• 年：2013
• 卷：729
• 期：Complete
• 页码：589-595
• 全文大小：4157 K

文摘

Since 2008, vertical tests of 1.3 GHz 9-cell cavities at the superconducting RF test facility (STF) in KEK have been carried out for the International Linear Collider (ILC). The tested cavities are mainly KEK-05 through KEK-22. Test results showed that KEK-12, KEK-13, KEK-17, and KEK-21 attained the unloaded Q value (Q<sub>0sub>) of 0.8¡Á10<sup>10sup> at the accelerating gradient (E<sub>accsub>) of 35 MV/m (ILC specification) only by the electro-polishing (EP) process. These four cavities had no problematic defect on any electron beam welding seams at their equators; however, field emission was still observed in the vertical tests. This paper reports on the recent progress of the cavity performance at KEK-STF, along with a detailed analysis of problematic defects and the effect of the local mechanical grinding.