Electron beam extraction from a broad-beam vacuum-arc metal plasma source

We describe experiments demonstrating the formation of a high current elect ron beam from a vacuum are plasma. A preexisting vacuum are ion source was used, with the extraction voltage reversed in polarity so as to form an ele ctron beam rather than an ion beam; no other changes were required. The bea m formed was of energy up to 33 keV, beam current up to 70 A, beam diameter about 10 cm, pulse width 500 mu s, and energy density up to 25 J/cm(2). Th is kind of source can be used for material surface modification.