RF electron source
Radio frequency (RF) plasmas are attractive as electron beam sources because they allow for a design where the cathode dose not participate in electron production while providing high efficiency and long life operation. Traditionally, hollow cathodes or tungsten filaments have been used as electron sources because of their high electron current density and relatively low power requirements. However, their operational lifetime is limited by cathode and filament deterioration, contamination, and barium diffusion rates, and in some cases requiring a large amount of inert feed gas, thus rendering them less suitable use in corrosive environments and sustained use. The Non-ambipolar Electron Source (NES) is a device that produces electron beams from plasma created with RF fields in a magnetized plasma combined with electron extraction by electron sheaths.