Triode hollow cathode electron gun for linear particle accelerators

A triode hollow-cathode electron gun configured to provide electrons and substantially mitigates the impact of back-streaming electrons, the triode hollow-cathode electron gun comprising;

• a hollow cathode with a concave surface configured to emit a beam of electrons, wherein the cathode is impregnated with Barium to enhances emission of the beam of electrons by lowering work function of the cathode, and wherein the hollow cathode includes an axially-oriented cylindrical channel configured to accommodate back streaming of the beam of electrons;
• a heating filament configured to provide heat to the hollow cathode enabling a thermionic emission process;
• an anode configured to attract and focus the beam of electrons emitted from the hollow cathode by maintaining a positive voltage potential relative to the cathode;
• a control grid configured to control or modulate and focus the beam of electrons emitted from the hollow cathode, wherein the control grid has a concave profile;
• and
• a protruding sleeve that is substantially centered on the axis of the triode hollow-cathode electron gun and configured to maintain a convergent shape and a trajectory of the emitted beam of electron, wherein the protruding sleeve increasing the laminarity of the beam of electrons by reducing undesirable transverse momentum of the beam of electrons, and wherein the sleeve is further configured to inhibit release of Barium from the cathode thereby increasing cathode life.