变焦-临界穿透束流极值法测量电子束流动态焦点——一种焦点测量方法介绍

Method of varying focus-extremum of critical penetrating current measuring electron beam dynamic focal spot

通过试验研究发现了电子束焊接过程中工件传导电流的传导比均值与输入束流的函数规律 ,函数的极大值是电子束焊接动态过程工件被穿透的临界状态转变点。利用电子束焊接过程的临界穿透束流特性 ,讨论了电子束受金属蒸气影响后的焦点状态与漂移空间传输的电子束焦点状态存在不同特性 ,提出了一种测量电子束焊接过程动态焦点的方法 ,变焦

With studying conduction current of workpiece, the rules between average ratio of conduction current of workpiece and electron beam current are discovered. The peak of average ratio of conduction current corresponds to the transferring point of critical penetration in the dynamic process of electron beam welding. By the characteristics of critical penetration current, the focusing states of electron beam influenced by metal vapor and transmitting in drift space are discussed. The concept of dynamic focal spot of electron beam is put forward. The method of measuring dynamic focal spot of electron beam is presented, through varying focus-extremum of critical penetration current.