Continuous and pulsed electron beam production from an uninterrupted plasma cathode

• Novel operation of a hollow cathode plasma electron beam source
• The source produces continuous or pulsed beam without interrupting the plasma.
• Electron beam energy and current are completely independent.
• The source is potentially useful for material processing applications.

Electron extraction from a hollow cathode plasma discharge through a primary anode, biased with a DC accelerating potential, is controlled to produce either a pulsed or a continuous electron beam without interruption of the discharge. The beam is on while a secondary anode, interior to the hollow cathode, is electrically isolated. While the primary and secondary anodes are electrically connected, the beam is off. Pulses as short as 10 μs have been produced, rise times are < 1 μs, the maximum beam-on duration is unlimited, and almost any duty cycle is possible. This source has been operated up to 3 kV and has produced beams of up to 80 mA.