层叠平板Blumlein线加载高梯度绝缘微堆耦合效应仿真分析

Simulation analysis of coupling effect during multi-plate Blumlein lines loading high gradient insulator

针对介质壁加速器中加速单元因耦合问题输出效率降低的现象,利用基于时域有限差分法的电磁场仿真软件,分别对一组和三组、单级和15级层叠平板Blumlein线加载高梯度绝缘微堆进行了分析。结果表明,较多的平行电极使层叠B线自身带有较大的耦合电容,会导致输出前沿变慢和输出幅值降低。三组层叠B线同时工作时输出效率降低,主要因为相邻组的层叠B线会作为在本组的耦合电容而严重分流,同时,相邻组对本组放电也会影响本组输出效率。将各级B线旋转一定角度呈扇形以减小平行电极有效相对面积,以此降低自身耦合电容,取得一定效果。

Due to the coupling problem,the output efficiency of the accelerating unit for the dielectric wall accelerator is reduced.With electromagnetic field simulation software based on FDTD method,the multi-plate Blumlein lines loading the high gradient insulator(HGI)is analyzed.The simulation includes one and three groups of 1-stage and 15-stage Blumlein line(BL)respectively loading HGIs.The results show more parallel electrodes in multi-BLs bring itself a large coupling capacitance,which leads to a slower rising edge and a lower amplitude.The output efficiency drops when three groups of multi-BLs work together because the adjacent group of multi-stage-BLs become a coupling capacitor and split current seriously.At the same time,the adjacent group of multi-stage BLs also discharge and affect output efficiency.A preliminary optimization is studied.By rotating every BL stages a certain angle to reduce the effective opposite area of parallel electrodes,the group of multi-BLs decreases its own coupling capacitance,and some benefit achieved.However,it requires further verification whether the optimization can reduce the coupling capacitance between the BL modules.