电子束焦斑偏离轴线中心的现象严重影响器件辐射效应实验的效率.介绍了一种简单有效的抑制电子束焦斑偏心的方法,研制了一种小尺寸不锈钢阴极,比较了不锈钢阴极和传统环形天鹅绒阴极在“强光一号”装置上的实验结果.实验结果表明对于小尺寸不锈钢阴极,最大辐射剂量位于靶面中心的概率为67%,位于35 mm圆圈内的概率为100%.相比传统环形天鹅绒阴极(最大剂量落于中心位置的概率约20%,有60%以上概率偏离中心2~3 cm)的实验统计数据,焦斑的偏心现象得到明显的抑制.

Focus spot drift of electron-beam seriously influences the radiation experimental efficiency of electronic devices.A simple method was introduced which could restrain the focus spot drift of electron-beam in the paper.A small stainless cathode was designed and experimented.The experimental results of small cathode were compared with the results of classical annular velvet cathode.It is shown that the probability of the spot stays at the center of anode is about 67%,and the probability of the spot stays at the circle area with diameter of 35 mm is about 100%.Focus spot drift was obviously restrained using the small stainless cathode,while the probability of the spot stays at the center of anode is only about 20%,and the probability of the spot stays at circle area with diameter of 40-60 mm is higher than 60% for the annular velvet cathode.