液态金属离子源发射系统电场的模拟分析

Electric Field Simulation of Emission System of Liquid Metal Ion Source

发射系统是液态金属离子源的关键部件之一,它的性能的优劣直接影响到整个离子源的工作稳定性和可靠性。因而对其发射系统进行仿真分析,可以很好地指导液态金属离子源的设计制造。本文采用国际上重视的动态喷流柱模型,利用模拟电荷法对液态金属离子源的发射系统的电场进行了计算分析,画出了发射尖端电场强度随不同参数变化的曲线,得出发射尖端表面场强与球冠半径、发射体突出臂长度密切相关,而与引出电极的结构关系甚小的结论,因此液态金属离子源发射特性(如角电流强度)的改善,必须在发射尖的设计制作上下功夫。从而为液态金属离子源的设计提供了一个有效的辅助工具。

Electric field of the emission system of a liquid metal ion source was simulatod, based on the conventional dynamic protrusion model and the widely used charge simulation method. Various factors, including the apex geometry of the emitter tip, the protrusion length, and the simulated charge distribution, were considered. Our simulated results show that the radius of the hemispherical tip apex and the protrusion length significantly affect the spatial electric field distribution surrounding the tip surface. We suggest that optimization of the tip geometry considerably improve the performance of the liquid metal ion source.