Investigation on pulse properties of impregnated barium scandate dispenser cathodes

Abstract

In this paper, an impregnated barium scandate dispenser cathode developed primarily for application in microwave tubes, especially in gyrotrons, is investigated in the following aspects: (1) pulse emission ability and work function distribution; (2) electron initial velocity distribution in pulse operation; (3) the effect of pulse duration ratio; (4) the anomalous Schottky effect under intensive electric field. Some useful results are obtained: the pulse current density is higher than 20 A/cm2 (whenT K =850°C); the anomalous Schottky effect is observed when the field intensity is higher than 104 V/cm; the cathode has flatJ G −fτ characteristic when the pulse duration ratio is in the range of 5×10−3−4×10−2 and an emission current density of 8.8 A/cm2 is drawn. Finally, the experimental results are discussed in relation to papers of the cathode surface analysis published at home and abroad.