一种新型周期永磁聚焦系统过渡区的设计

Design of new structure of transition region for periodic permanent magnetic focusing

分析了过渡区中电子注调节的基本原理,设计了一种渐变式的过渡区结构,其注腰半径为0.8mm,周期均匀磁场峰值为0.29 T,周期为4.5 mm,压缩比为22。该结构能够在减小电子枪压缩比的情况下对电子注进行再压缩,得到符合互作用要求的电子注。将采用渐变式过渡区结构的电子注匹配与采用传统方法的电子注匹配进行了比较,模拟结果表明:采用渐变式过渡区结构匹配电子注不仅能有效改善电子注的层流性(波动性为8%),还能够提高电子光学系统的稳定性。根据此方法对Ku波段6 kW行波管的电子光学系统进行了模拟计算,得到了良好的设计结果。

Considering that generation and maintain of small radius, high power beam is restricted by the compression ratio of electron gun, the effect of magnetic field on electron trajectories in transition region was analyzed. A method was presented to compress the beam by changing the magnetic field in transition region gradually. Compared with the traditional one, the method requires lower compression of electron gun while providing small radius beam for interaction, it also optimizes the beam quality. The method was used to simulate an electron optical system for Ku-band 6 kW TWT, some good results are obtained.