电子束中Boersch效应的实验研究

在现代电子光学与电子束技术研究中，Boersch效应作为离散空间电荷效应的一个主要特征，越来越引起了人们的重视。本实验设计并制作了一台观察和测量Boersch效应的实验装置，并进行了动态真空实验。实验装置的电子光学系统包括层流电子枪、聚焦透镜、准直透镜和拒斥场分析器等部分。对实验结果及数据进行了处理和分析，观测到了电子能量分布的反常增宽现象并测量了能量分布曲线。当束腰区束流为微安量级时，测得的电子能量分布宽度为1～3eV，并且得出了随着束流强度的增加能量分布展宽的近似规律。

Experimental Studies of the Boersch Effect of Electron Beams

effect, as one of the major discrete space charge effects of electron beams, has attracted an increasing research interes in modern electrooptics and in electron beam technology. Recently we have successfully developed a dedicated instrument to study Boersch effect of the electron beam, which includes a laminar flow elec-tron gun, a focusing lens,a collimation lens,and a retarding field analyzer With this instrument,we measured the electron energy distribution in vacuum and observed the anomalous energy spread about 1~3 eV when the beam current in the crossover area is of the order of microampere. An approximated relationship between the energy spread and the current of the electron beam was also proposed.