Spurious emission and Arc suppression in electron guns

Electron guns for RF sources typically use barium dispenser cathodes to produce electron emission. Barium and oxygen diffuse to the emission surface whenever the cathode is hot to replace that lost by evaporation. The barium combines with the oxygen to form barium oxide, which reduces the surface work function. Barium that evaporates from the surface is deposited on nearby surfaces, including grids and high voltage electrodes. If the barium recombines with oxygen, it 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 by preventing barium oxide formation.