BASIC PRINCIPLE OF ELECTRON BEAM WELDING(EBW)
Electron beam welding which utilises a heat source of electrons which are accelerated by an electric field to mextremely high speeds and focused to ma sharp beam by electrostatic or electromagnetic fields , which is used for welding a wide range of metals in thickness ranging from foils to extremely thick sections.Electrons are produced at the cathode surface by thermonic emission. The most common emitter material used is tungsten, which contains a small percentage of rhenium. They are being accelerated by high voltage applied between the cathode and the anode. The shape of the bias cup and anode are so designed that the electrons are focused by the electrostatic field and emerge through the anode aperture as a collimated beam. This beam impinges on to the target by the magnetic field of focusing lens, which permits the high concentration of power at the point of impact. The kinetic energy of the electrons is transferred into heat energy which melts / fuses the metal. In general, electron beams in the energy ranges from 100 kV to 10 MV with average powers ranging from 1 kW to 500 kW.