微秒长脉冲有磁场高功率微波二极管真空界面设计

Design of a vacuum interface of a microsecond timescale HPM diode with guiding magnetic field

介绍了一种微秒长脉冲有磁场的真空二极管界面的设计和实验结果。采取了三种措施来抑制沿面闪络:一是阴极电子束挡板,用来拦截来自阴极和电子束漂移管的回流电子束;二是接地屏蔽板,使电场等势线和界面成约45°角,使阴极三结合点处发射的电子远离绝缘板;三是降低阴极三结合点处的场强,并使用一悬浮电位的金属环阻止电子倍增过程。计算了二极管内电场、磁场分布和电子束的运动轨迹并据此优化了真空界面的结构,实验验证了该二极管真空界面可以在400 kV、800 ns条件下正常工作,可以支持长脉冲高功率微波器件的研究。

Long pulse high power pulse driver in the microsecond range is an important platform for conducting high power microwave(HPM) device studies and one of the key technologies is to prohibit surface flashover of the vacuum diode interface under the conditions of long pulse duration and the presence of guiding magnetic field. We report a design of a vacuum interface which works in the microsecond timescale with guiding magnetic field. Three measures are adopted to suppress the surface flashover. First is a cathode electron beam blocker, which intercepts the electron beam from the cathode and electron beam drift tube;Second is a grounded plate field shaper, which makes the electric field equipotential line and the interface form an angle of about 45°, so that the electrons emitted from the triple junction are directed away from the insulator;Third is a floating metal ring, which prevents the electron multiplication if emission from cathode stalk triple junction does occur. The electric field and magnetic field in the diode and the trajectory of electron beam are calculated, and the geometry of the vacuum interface is optimized.Experiments show that the vacuum interface of the diode can work at voltage of 400 kV and pulse width of 800 ns,which allows the study of long pulse high power microwave tubes.