无箔二极管参数对电子束包络的影响

Influence of Foilless Diode Parameters on Electron Beam Envelope

针对O型高功率微波产生器件采用的无箔二极管结构,在引导磁场为0.6T的条件下,研究了二极管电压、电流、阴阳极间距、漂移管管头倾角和阳极半径等参数对电子束包络的影响。结果显示:阴极附近和漂移管内部的电子束包络随二极管参数的变化规律有明显差异,阴极附近电子束包络幅值较小并不能确保漂移管内部电子束包络幅值较小;适当增大二极管阻抗有助于减小漂移管内电子束包络幅值;受电子束径向运动的空间周期性影响,漂移管内部的电子束包络幅值随阴阳极间距增大会出现振荡变化;漂移管管头倾角超过90°后,管头倾角对电子束包络幅值影响很小;当阳极半径明显大于阴阳极间距时,阳极半径对漂移管内电子束包络幅值的影响也较小。通过合理优化二极管参数,可以有效减小电子束包络幅值,这是低磁场O型高功率微波器件稳定工作的重要基础。

This paper studies the influences of diode voltage,beam current,diode gap,slope angle of drift tube head and anode radius on the electron beam envelope in the foilless diode which is usually adopted in O-type high power microwave(HPM)generators under a guiding magnetic field of 0.6 T.The results demonstrate that the dependence of beam envelope amplitude near the cathode on foilless diode parameters may differ from that in the drift tube,and a smaller beam envelope amplitude near the cathode cannot ensure a smaller beam envelope amplitude in the drift tube.Moderately increasing the diode impedance is beneficial to reduce the beam envelope amplitude in the drift tube.Meanwhile,due to the spatial periodicity of radial motion of electron beam,the beam envelope amplitude in the drift tube will present periodic change when the diode gap increases.The influence of slope angle of drift tube head on beam envelope is slight when the angle exceeds 90°,and the anode radius also has just very limited influence on beam envelope in the drift tube as long as it is obviously larger than the diode gap.Clearly,the beam envelope amplitude can be decreased effectively by optimizing the diode parameters,which can provide an important condition for O-type HPM generators operating stably under low guiding magnetic field.