摘要
利用电子束流对高速定向稀薄气体束流的碰撞电离需要在极短时间内产生离子束流,从而收集到较窄的离子脉冲信号。传统热阴极固有的热响应时间限制了电子发射精度,为此,论文设计并仿真了一种能够产生具有指定能量的高脉冲电子束流的热阴极脉冲电子枪,通过从阴极表面提前引出一定数量的热电子,使其能够实现纳秒级脉冲电子束流控制,克服了阴极热响应产生的时间延迟影响,保障了对稀薄气体分子的高效电离。该电子枪由热阴极、反射罩、加速栅极、聚焦极与接地屏蔽罩等部件构成,同时根据使用需求设计了匹配的移动机构,在使用时调节电子束流与需要电离的分子束流的距离,以优化电离效率。仿真表明,该热阴极脉冲电子枪能够在40 ns的脉冲电压周期内产生约70 eV的脉冲电子束流,电子发射效率达13.58%,验证了其用于高速定向稀薄气体束流碰撞电离的有效性,为后续实验研究与应用提供了理论与数据基础。
The collision ionization of high-speed directional rarefied gas beam by an electron beam requires the generation of ion beam within an extremely short time,so as to enable the collection of narrower ion pulse signals.A significant challenge arises from the inherent thermal response time of conventional hot cathodes,which can limit the temporal precision of electron emission.To overcome this limitation,this study designed and simulated a hot cathode pulsed electron gun capable of generating a high-current pulsed electron beam with specified energy.The key innovation involves pre-extracting a population of thermal electrons from the cathode surface,forming a readily available“electron cloud”.This approach enables nanosecondscale pulsed electron beam control,effectively bypassing the delay associated with cathode heating and allowing for efficient ionization of rarefied gas molecules.The electron gun comprises several key components:a hot cathode,a reflector,an acceleration grid,a focusing electrode,and a grounded shielding cover.A compatible translational mechanism was designed,allowing for precise adjustment of the distance between the electron beam exit and the molecular beam during operation,thereby optimizing the ionization interaction region.Simulations were conducted using COMSOL Multiphysics software,incorporating the Particle Tracing Module to model electron dynamics under transient electric fields.The electrostatic field distribution and electron trajectories were analyzed in detail.Simulation results demonstrated that the hot cathode pulsed electron gun could generate a pulsed electron beam with an energy of approximately 70 eV within a pulse voltage period of 40 ns.The system exhibited excellent electron emission characteristics,with a simulated emission efficiency of 13.58%and a collection efficiency of 100%under the defined conditions.Furthermore,collision ionization simulations with N_(2)gas yielded an ion production rate consistent with theoretical predictions,demonstrating an error of only 3.297%.These findings serve to validate the effective collision ionization performance of the electron gun and lay a valuable groundwork for future experimental verification and application.
作者
史心怡
张虎忠
李得天
李兴达
习振华
李刚
康伟东
SHI Xinyi;ZHANG Huzhong;LI Detian;LI Xingda;XI Zhenhua;LI Gang;KANG Weidong(Science and Technology on Vacuum Technology and Physics Laboratory,Lanzhou Institute of Physics,Lanzhou 730000,China;School of Mechanical Engineering and Automation,Northeastern University,Shenyang 110819,China)
出处
《真空与低温》
2026年第2期129-138,共10页
Vacuum and Cryogenics
基金
甘肃省科技重大专项计划(23ZDGA013)。
关键词
热阴极
脉冲电子枪
碰撞电离
定向流
hot cathode
pulsed electron gun
collision ionization
directed flow
