The theoretical analysis to the RF cavity at China Spallation Neutron Source (CSNS) , a typical ferrite-loaded coaxial resonant cavity operating in swept condition by using the coaxial transmission line theory is presented. The modeling method of the cavity in the CST three-dimensional simulation software is also described in details, especially about the use of ceramic insulators representing resonant capacitors. The characteristics of the cavity obtained by the coaxial transmission line method, the CST simulations and the measurements have been compared, and are consistent. The parasitic mode induced by the Busbar has been studied by the CST simulations and the measurements, and different improvement methods over the prototype cavity are given. The impact of the filling factor of ferrite rings on the frequency tuning in the cavity has also been analyzed, and it turns out that a larger tuning range for the bias current is needed for a shorter cavity.%利用同轴线理论分析了扫频工作的中国散裂中子源(CSNS)铁氧体加载同轴谐振腔的主要性能参数.给出了铁氧体加载腔在三维电磁场仿真计算中的建模过程,在场分析的基础上提出了陶瓷介质等效谐振电容的方法.将模拟计算得到的腔体的谐振特性与同轴线理论计算和实际腔体测量结果相比较,三者吻合得非常好.通过对腔体样机母排引入的寄生模的实验和模拟研究,提出了解决寄生模问题的方法;通过对腔体内铁氧体环的填充系数的研究,给出了短尺寸腔的扫频工作方案.
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