Characterization of an insulated SCL non-relativistic electron-beam diode operating at 300 kV/cm

High current density (>100 A/cm/sup 2/) electron beam diodes operating beyond 250 kV/cm in a 1 cm gap configuration are described. The principal features of the electron source are the high current density and high field without the onset of vacuum arcs or arc collapse prior to gap closure. The electron beam diode was controlled by a variable pulse-width output Marx generator. Fields to 600 kV/cm were applied for 25 to 30 ns, and to 300 kV/cm during space-charge limited current conduction at pulse lengths of 100 to 120 ns. Evidence of the transition to space-charge limited unipolar flow and transition to bipolar space-charge limited flow was obtained. Traces of the typical behavior and the different transitions are shown. Beam uniformity was measured by using a set of Faraday cups. The Faraday cup setup was then used to demonstrate suppression of electron emission from surfaces coated with a dielectric film.<
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