设计了一种非浸没式小型化轴向无箔二极管, 其阴极发射区位于螺线管中心孔以外, 采用螺线管、永磁体和软磁体构成的复合引导磁场系统。采用CST优化设计二极管结构, 使其满足800 kV电压下绝缘要求; 优化设计磁场系统结构及物理参数, 使其满足引导强流相对论电子束高效率传输的要求。采用粒子模拟（PIC）软件仿真电子束产生及传输过程, 验证其高传输效率。设计的阳极筒直径比原结构缩小约40%, 在产生同样均匀区轴向磁场强度情况下, 引导磁场重量和功耗比原结构降低约40%, 仿真结果显示主引导磁场0.85 T下, 8 kA电流能够实现100%传输效率。

A composite guide magnetic field system for axial foilless diode was designed, which included a solenoid, a permanent magnet and a soft magnet. The cathode emission region was put outside the solenoid magnet, to get smaller inner radius of solenoid and lower electric field on cathode rod surface. The permanent magnet and the soft magnet compensate magnetic density of the cathode emission region, to meet the requirement for stable transmission. Weight and power of the guide magnetic field system were both reduced more than 40% as compared with the system using a classical solenoid magnet. PIC simulation on transmission characteristic of electron beams in the composite guide magnetic field system was studied, which proved that axial electron beams could be stably transmitted in the system.