S波段相对论速调管放大器输入腔的3维分析与模拟

 利用3维软件设计了适用于S波段相对论速调管放大器的单重入输入腔,该腔体采用了偏心设计,以便减小耦合孔处的不均匀场对腔间隙场的影响，分析了腔体耦合孔尺寸对腔间隙场均匀性的影响；建立了带输入波导结构的3维输入腔开放腔模型，并应用此模型，采用3维PIC程序模拟了注入微波功率、束直流对输入腔间隙后束流调制的影响。研究结果表明：耦合孔尺寸对腔间隙电场均匀性影响较大，当耦合孔离轴越近时，腔间隙场越不均匀；在结构参数和束参数固定的条件下，基波电流调制深度随着间隙电压的增加而增加，但达到最大基波调制电流的漂移距离几乎不变；在结构参数和注入微波参数固定的条件下，束直流越大，达到最大基波调制电流所需的漂移距离越短。研究结果为腔体的设计和输入腔束流调制实验提供了参考依据。

Three dimensional analysis and simulation of input cavity for S-band relativistic klystron amplifier

In this paper, high frequency characteristics analysis on an input cavity of an S-band relativistic klystron amplifier is presented. The influence of large coupling hole on symmetry and uniformity of the electric field in the gap region is discussed and a bias design in the input cavity is used to reduce the influence. The field in the gap region are sensitive to the coupling hole size and when the coupling hole is closer to the axis, the field in the gap region is more asymmetric. A three-dimension fully electromagnetic particle-in-cell(PIC) code is used to simulate the fundamental harmonic modulated current while the electron beam is propagating the input cavity gap. The simulation results show that the amplitude of the fundamental harmonic modulated current is relative to the gap voltag