不同结构盒栅式电子倍增器模拟计算

Impact of Grid-Dynode Geometry on Characteristics of Box-Type Electron Multiplier: A Simulation Study

利用CST三维电磁仿真软件对不同结构的盒栅式电子倍增器进行建模,采用控制变量的分析思想,模拟计算不同打拿极结构下的电子倍增器内电场分布、电子运动轨迹和倍增增益。数值仿真结果显示,不同结构打拿极电子倍增器内部电场稍有不同,并且导致倍增效益有所不同。在具有相同路径的8级打拿极结构的情况下,增益效果由强到弱的顺序为多边形、方形、弧形、三角形。多边形打拿极在二次电子发射材料镀膜区域不同的情况下,电子倍增器的增益效果具有很大的差异。

The field distributions,in the electron multiplier with eight stages of box-shaped grid-dynode assembly,were mathematically modeled,theoretically analyzed and numerically simulated with CST software.The influence of the box-shapes,including the boxes with a top-view of pentagon,square,quarter-circle and triangle,on the electric field profiles,electron trajectories and multiplication gains was investigated.The simulated results show that the box-shape has a major impact.To be specific,the impact factor of the box-shapes can be listed in a descending order: pentagon>square>quarter-circle>triangle.Theoretically speaking,the multiplication gain decreases from 835 to 65,because no secondary electron emission coatings are deposited on the two short-sides of the pentagon dynodes,made by truncating the two sharp angles of a right-angled triangle.We suggest that the simulated results be of some technological interest in design of box-type electron multiplier.