EQUIPMENT USED IN EBW
The electron beam equipment can be broadly divided in to the following sub systems.
Electron Gun and Beam Guidance System
The heart of the electron beam welding process is the electron beam gun assembly. Electrons are generated by heating a negatively charged emitting material to its thermionnic emission temperature range thus causing electrons can be attracted to the positively charged anode. The grid cup and the anode are shaped and positioned in such a way as to form the emitted electrons into a beam, which passes through the anode aperture.
Recent developments in electron beam welding equipment
In early days, the guns used were of the directly heated ribbon type, normally these are relatively low power electron beam guns. With the push to higher beam power levels, the difficulties of generating precision beams, control, stabilisation & reproducibility became more exacting. These are suffer from inconsistency and movement within the grid cup, the power density distribution was distorted by the ellipsoidal emission surface. To improve the performance of an electron beam heating, a little change in these conventional type electron beam guns is made by introducing a cathode which is to be heated by bombardment of electrons emitted from the heated filament. This change would make it more reliable at higher power continues operation for longer time. These type of electron beam guns are indirectly heated (bombarded) cathode type electron beam guns.