High current low energy plasma electron gun based on magnetic field controlled vacuum arc

Abstract

Summary form only given. A new high current low energy plasma electron gun has been developed and investigated. The electron gun is based on a vacuum arc discharge with a hollow anode. This discharge unit provides a stable, uniform plasma surface from which a high current density electron beam can be extracted. The current density of electron beam on collector was as high as 60 A/cm/sup 2/ with beam current about 40 A with relatively low energy that was less than 20 keV. To produce the desired electron emission current, the plasma density is controlled by magnetic field and arc current. Electron transportation efficiency (ratio of the collector current to the emission current) was higher than 70%. The electron extraction system provides acceleration and transport of a high density beam. The beam passes through the 8-mm diameter aperture. The source produces a long pulse (up to 50 /spl mu/s) electron beam with a high current density. A strong external axial magnetic field provides beam focusing and propagation, and due to that fact low pressures (1*10/sup -6/ Torr) can be reached. Different operating modes of the electron gun have been observed through the experiments. Physical processes of producing and transport of high current low energy electron beam, as well as possible application of the beam, are discussed.