一种飞秒电子衍射系统的设计与分析

Design of a Femtosecond Electron Diffraction System

设计了飞秒电子衍射系统,详细分析了影响系统时间分辨率的因素,如阴极的材料及厚度、阴极附近场强、聚焦方式、偏转灵敏度及扫描速度等.设计的电子枪采用35 nm厚的Ag阴极,阴栅之间场强为10 kV/mm,磁线圈聚焦,偏转灵敏度为26.3 mm/kV的平折扫描板,5.5 kV/ns的扫描电压斜率,最终获得了1.45×108m/s的扫描速度.计算出系统总的时间分辨率为500 fs左右.

A new designed FED system was introduced in this article and the components of the system were illustrated. The factors that affected the temporal resolution of the system were analyzed in detail, such as the material and thickness of the photocathode, electric field near the cathode, focusing method, deflection sensitivity and sweeping speed. Finally , designed a FED system with 3 5 nm - thickness Ag film , 1 0 kV /mm electric field near the cathode . Magnetic focusing was used and the deflection sensitivity was 26.3 mm/kV,the sweeping speed could reach up to 1.45 × 10^8 m/s,so the total temporal resolution was reduced to about 500 fs.