Working Chamber of EBW
The chamber is usually rectangular in shape and has heavy windows to permit viewing the work. Both high voltage machines and low voltage machines are available with work chamber that can be evacuated to high vacuum (or partial vacuum (10-4).The basic requirements of vacuum is the electrons need to flow in a beam from the emitter to the target unimpeded by the presence of any gas molecules that may cause scattering and slow down of the beam. The source of electrons is a tungsten filament heated to around 2200 °C. At this temperature, the filament will oxidise very quickly because of the presence of oxygen in air. The pumping equipment is usually completely automatic once the set up has been completed.