Abstract

Large-area electron guns are critical components in many high-energy gas laser systems. The secondary emission electron (SEE) gun, in which a beam is generated by ion bombardment of the cathode, offers an attractive option for pulsed laser applications. With this type of cold cathode gun, a dc voltage is applied to the cathode and the electron beam is controlled by modulating the source of ions in which resides a ground potential. This design greatly simplifies the electron gun power system. A SEE gun system has recently been developed which provides a 150-kV, 5- × 150-cm² beam at current densities of up to 12 mA/cm² (uniformity about ±10%) in 30-µs pulses at 30 pps. It is expected that the SEE gun can be easily scaled to beam voltages of >300 kV, beam areas >10,000 cm², peak current densities exceeding 1 A /cm², time-averaged current densities >0.5 mA/cm², pulse lengths of 0.1 µs to dc, and pulse repetition rates >1 kHz with good uniformity (±5%), high reliability, and long life (>1000 h). Furthermore, the inherent simplicity of the SEE gun results in low cost and a compact, lightweight system.

© 1989 Optical Society of America