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在高频加速系统中,加速腔的输入耦合器是至关重要的部分之一,其性能直接影响高频功率的耦合和加速腔的特性.北京正负电子对撞机重大改造工程(BEPCⅡ)中的高频系统中,超导高频加速腔采用的是同轴天线型功率输入耦合器,这是首次在国内采用的500MHz频率的大功率耦合器．本文中对这种超导腔耦合器的二次电子倍增效应情况、传输系数、热分布情况三方面的特性进行了研究．研究结果表明,耦合器在多个功率点存在二次电子倍增效应,必需采取相应的措施来改善其对耦合器的不利影响;通过对耦合器结构尺寸的优化使其在BEPCⅡ工作频率(499．8MHz)下能更有效地传输功率;通过模拟计算,得到了耦合器内外导体的热分布图象,为校核和改进冷却设计和布局的合理性提供了重要的依据．
In the high-frequency acceleration system, the input coupler of accelerating cavity is one of the most important parts, and its performance directly affects the coupling of high-frequency power and the characteristics of the accelerating cavity.The major renovation project of Beijing Electron Positron Collider (BEPCⅡ) In the high-frequency system, the superconducting high-frequency acceleration cavity is coaxial antenna-type power input coupler, which is the first time in the country with a 500MHz frequency high-power coupler. In this paper, the superconductor cavity coupler secondary electron multiplication effect, the transmission coefficient, the distribution of heat characteristics of the three aspects were studied. The results show that the coupler has secondary electron multiplication effect at multiple power points and corresponding measures must be taken to improve its adverse effect on the coupler. By optimizing the size of the coupler, it is required to operate at BEPC Ⅱ operating frequency (499). 8MHz) to transmit power more efficiently. Through the simulation calculation, the heat distribution images of the inner and outer conductors of the coupler are obtained, which provides an important basis for checking and improving the rationality of the cooling design and layout.