Long-pulse electron gun for laser applications

Abstract

Large-area electron guns are critical components in many high-energy gas laser systems. The secondary emission electron (SEE) gun 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 generated by secondary emission due to ion bombardment processes. The gun is controlled by modulating the source of ions which resides at ground potential. This design greatly simplifies the electron gun power system. SEE-gun systems have been developed which provide 150-220 keV beams at current densities exceeding 25 m(Alpha)/cm2 with current density uniformities of approximately ± 10% over areas of up to 5x150 cm2. Pulse lengths have ranged from 30 microsecond(s) to 20 ms at repetition rates from single-pulse to 30 Hz. It is expected that the SEE-gun can be scaled to beam voltages of greater than 300 kV, beam areas greater than 1 m2, peak current densities exceeding 1 (Alpha)/cm2, time-averaged current densities >0.5 m(Alpha)/cm2, pulse lengths of 0.1 microsecond(s) to dc, and pulse repetition rates >1 kHz with good uniformity, high reliability and long life. Furthermore, the inherent simplicity of the SEE-gun results in low cost and a compact, light-weight system.© (1991) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.