High-current, low-pressure plasma-cathode electron gun

摘要

Plasma-cathode electron gun structures capable of operation in low- pressure, e.g., 5×10.sup.-3 Torr, ionizable gas environments are disclosed. They utilize a thermionic emitter within an enclosure with a partially transparent electrode defining a plasma face. Spaced anodes are disposed adjacent the electrode to extract an electron beam from the plasma face. A magnetic system forms an inward directed field, and a portion of the plasma electrons are directed through this field to enhance ionization efficiency.