High-power performance and analysis of six X-band high-gradient accelerating structures

Le résumé fourni par la source

Six X-band accelerating structures with identical radio frequency (rf) designs have been developed and fabricated for the Very Compact Inverse Compton Scattering Gamma-Ray Source (VIGAS) project at Tsinghua University, representing the first large-scale deployment of such devices with consistent rf performance in China. This article presents the tuning, conditioning, and high-power performance results of these structures, with emphasis on in-depth analysis of conditioning processes and rf breakdown phenomena. The six structures achieved an accelerating gradient of 80 MV / m with a breakdown rate of no more than 1 × 10 − 4 per pulse after systematic conditioning. Our study reveals several critical aspects of rf breakdown behavior in X-band high-gradient accelerating structures. Key observations include the localization of breakdown events in regions of high electric field, particularly in cells adjacent to the input coupler; a power-law dependence of the normalized breakdown rate on cumulative pulse count, with notable variation in fitting parameters across different structures; and a two-exponential statistical distribution characterizing breakdown intervals. These findings offer important implications for optimizing conditioning strategies for high-gradient rf structures. Furthermore, the analysis of performance variations among nominally identical structures uncovers underlying physical mechanisms governing breakdown, establishing a useful benchmark for the development of future compact accelerator facilities.

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