Development of hollow-cathode plasma electron gun for operation at forepump gas pressure

Summary form only given. The characteristics, performance and design features of a new version of a filamentless plasma-cathode electron gun for beam generation in the forepump gas pressure range are presented. The plasma cathode is based on a hollow cathode DC discharge. Using the method of "grid stabilization" it was possible to generate an e-beam at a background gas pressure as high as about 10/sup -1/ Torr. This pressure can be easily obtained by using mechanical pump only. The electrode configuration of the plasma-cathode e-gun consists of a 50 mm diameter, 100 mm length hollow cathode, plane anode, and electron extractor. The hollow cathode bottom has a centric hole; its diameter was either d/sub c/=16 mm or 25 mm. Electrons are extracted from the plasma surface through the anode hole of d/sub a/=16 mm. The extractor hole has the same diameter (d/sub e/=d/sub a/), and distance of the accelerating gap is 10 mm. The hollow cathode was made from stainless steel, and anode and extractor were made from copper. There are also ceramic insulators and an air cooling system. To produce an axial magnetic field (up to 0.1 T) both in discharge and accelerating regions a solenoid coil was used. The operation of the gun with a magnetic field up to 0.1 T was investigated.