METHOD OF TREATING A WORKPIECE WITH AN ELECTRON BEAM

摘要

In electron beam welding, the vacuum chamber (10) in which a workpiece (18) is located is hermetically connected to a vacuum chamber (39) containing the electron beam gun (26). The chamber (10) is kept at a vacuum of 1 x 10<-><4> Torr while the chamber (39) is at a vacuum of 1 x 10<-><5> to 1 x 10<-><6> Torr. In order to minimize discharge phenomena caused by gas molecules generated at the workpiece during the welding, the distance between the electron beam gun and the surface of the workpiece is greater than the main free path of these gas molecules e.g. 1.85 m. Two focussing coils (42,48) are arranged to prevent the expansion of the electron beams.