太赫兹行波管非对称降压收集极设计

Design of an asymmetric multi-stage depressed collector for terahertz traveling wave tubes

多级降压收集极是太赫兹行波管中回收废电子注的重要部件,对整管工作效率有重要影响.为提升整管工作效率,提出一种非轴对称结构的太赫兹频段行波管降压收集极的设计方案.通过研究注波互作用后的废电子注能量特性,设计了轴对称太赫兹频段行波管降压收集极结构,再采用非轴对称结构进行优化.三维粒子模拟计算结果显示,在考虑二次电子发射的情况下,采用三级轴对称降压收集极的太赫兹行波管,最佳回收效率为79.30%,粒子回流率为3.12%,整管工作效率为4.47%;而当采用三级非轴对称结构降压收集极时,太赫兹行波管的回收效率升至89.50%,粒子回流率降至0.53%,整管工作效率为8.38%.采用非对称结构设计的降压收集极可有效提高太赫兹行波管的整管工作效率.

The multi-stage depressed collector(MDC)plays an important role in the terahertz traveling wave tube(TWT)for recovering spent electron beam,which has significant impact on its working total efficiency.For the purpose of improving the efficiency of the whole tube,the designscheme method of a depressed collector with non-axisymmetric structure in terahertz TWT is proposed.The axisymmetric depressed collector for terahertz TWT is designed by analyzing the energy characteristics of spent electron beam after beam-wave interaction,and then on-axisymmetric structure is used for optimization.The results of three-dimensional particle simulation(PIC)show that for the TWT with the three-stage axisymmetric MDC,the optimal recovery efficiency is 79.30%,electron reflux rate is 3.12%,and the working efficiency is 4.47%when considering the secondary electron emission.For the TWT with the three-stage non-axisymmetric MDC,the recovery efficiency increases to 89.50%,the particle reflux rate decreases to 0.53%,and the whole tube working efficiency reaches 8.38%.The working efficiency of the whole tube can be increased effectively by taking the asymmetric structure.