高性能强流脉冲电子束源关键技术研究

Development of high performance, high-current pulsed electron beam sources

强流脉冲电子束源是高功率微波系统的核心部件之一,针对未来应用需求,亟需从绝缘、束流输运和热管理等多个方面提升强流束源技术性能。介绍了国防科技大学在高功率微波源用强流真空电子束源方面的研究进展。针对高功率微波管保真空需求,基于陶瓷金属钎焊,设计并研制了一种强场陶瓷真空界面,耐压大于600 kV、平均绝缘场强达到44 kV/cm、耐受脉宽大于80 ns,重复频率运行稳定;研制了一种基于SiC纳米线的强流电子束源冷阴极,在90 kV/cm的场条件下获得了1.17 kA/cm^2的束流密度,相比传统天鹅绒阴极,SiC纳米线阴极的宏观电稳定性、发射均匀性及运行寿命均得到显著提高;针对相对论返波管,研制基于螺旋水槽型的强流电子束收集极,克服了高比能和低流速的矛盾,耐受热流密度达到10^12 W/m^2,能够满足系统长脉冲、高重复频率运行要求。

As a core part,the performance of a high-current electron beam source is inevitably essential for high-power sources and accelerators.The attractive features are high-electric field vacuum interface,high quality high current density electron emission,and high peak thermal load collector,which are compatible with high repetition rate operations.This paper presents an optimized ceramic insulation structure with hold-off voltage pulse of 600 kV,100 ns,and 5 Hz.Mechanisms and surface improvements are developed.Large-scale,well-aligned SiC nano-wires as high-current,pulsed electron beam emitters are explored.They show an superior advantage on cathode lifetime and emission quality.In addition the thermal control and cooling methods for a repetitively operated high current collector are gathered,and the specially designed device can work stably with a heat flux of 10^12 W/m^2.These efforts make solid contributions to the HPM sources for practical use.