Hollow-cathode plasma electron gun for beam generation at forepump gas pressure

The characteristics, performance, and design feature of a filamentless plas ma-cathode electron gun for beam generation in the forepump gas pressure ra nge are presented. The plasma cathode is based on a hollow-cathode direct c urrent (dc) discharge. Using the method of "grid stabilization" it was poss ible to generate an e beam at a background gas pressure as high as about 10 (-1) Torr. This pressure can be easily obtained by using mechanical pump on ly. The operation of the gun with a magnetic field up to 0.1 T was investig ated. The presence of a magnetic field (B field) is often required, for ins tance in plasma chemistry and surface treatment processes. The effect of th e B field both on discharge and emission parameters of the gun are observed . The results obtained can be explained based on the concept of electron co nfinement and motion across the B field. With the accelerating voltage up t o 8 kV, the gun is able to generate an electron beam of about 0.7 A dc. (C) 1999 American Institute of Physics. [S0034-6748(99)03507-8].