Spurious emission and arc suppression in electron guns

Abstract

Electron guns for RF sources typically use barium dispenser cathodes to produce electron emission. Barium diffuses to the emission surface whenever the cathode is hot to replace that lost by evaporation. The barium forms barium oxide to reduce the surface work function. Barium that evaporates from the surface is deposited on nearby surfaces, including grids and high voltage electrodes. The barium can result in spurious electron emission and arcing from these surfaces. This research is investigating surface coatings to suppress spurious electron emission from these surfaces.