Electron beams under fore pump pressure range: Generation and some applications

The paper presents review of recent results of development and some applications of plasma cathode sources generating electron beams in so called fore-pump pressure range (1÷15 Pa). This kind of electron sources has no alternatives for electron beam production under relatively high pressure. Essential progress was reached recently in generation of continues electron beams with energy up to 20 keV for narrow focusing and 10 keV for ribbon configurations. Several specific problems were solved for e-beam generation at this pressure range. Main of them are: high probability for electrical breakdown of accelerating gap, essential influence of back ion stream both on emission electrode and emitting plasma, formation of secondary plasma in beam propagation area as well as intensive beam-plasma interaction. Specific peculiarities take place in case of ribbon type electron beam generation. They are local maximums in current density distribution across the beam. Due to rather high pressure, electron beams may be used as for metal melting, evaporation, treatment, so for dielectric processing: melting, welding, drilling etc.