US Patent 9064671 Method and apparatus for generating electron beams

Various embodiments of the present invention relate to a plasma electron source apparatus. The apparatus comprises a cathode discharge chamber in which a plasma is generated, an exit hole provided in said cathode discharge chamber from which electrons from the plasma are extracted by an accelerating field provided between said cathode discharge chamber and an anode, at least one plasma confinement device, and a switching mechanism for switching the at least one plasma confinement device between a first value allowing for electron extraction from the plasma and a second value prohibiting electron extraction from the plasma. Associated methods are also provided.