Electron-beam welding is a process used for welding stators and rotors, and hence highly-stressed safety class 1 components. The major advantage of electron-beam welding is that high welding speeds can be achieved to produce deep, narrow and parallel weld seams. The narrow seams and high levels of parallelism afforded by the process keep distortion to a minimum.
The electron beam is a stream of negatively charged particles (electrons) generated by a triode system composed of a cathode, a control electrode (Wehnelt cylinder) and an anode. A high voltage electric field (acceleration voltage) is applied which supplies the electrons with kinetic energy. By applying an acceleration voltage of 150 kilovolts, the electrons can achieve speeds of about 60 percent of the speed of light. When the electrons strike the surface of the workpiece their kinetic energy is converted into thermal energy. In air, an electron beam diverges strongly through collision with air molecules; this is prevented by providing a vacuum in the beam generator (where the electron beam is produced) and in the working chamber.