Laser-activated electrical switching characteristics of high-current, low-loss thermionic diodes

This final report summarizes the research from February 1979 to September 1982 conducted under Contract N00014-79-C-0131, on experimentally investigating laser-activated electrical switching of and electron beam formation from cesium coated thermionic and photoemissive surfaces. Two areas were investigated. The first dealt with thermionic emission of electrons from pulse laser heated cesiated surfaces. High power irradiation of cesium-coated metallic targets has generated very dense electron beams. Partially space-charge-limited currents of 2500 A and current densities of 3900 A/sq cm from 9 mm diameter tungsten-rhenium targets have been measured when irradiated by unfocussed 50 MW, 20 ns pulses from a Nd:glass Q-switched laser. The second area of research focussed on CW laser stimulation of cesiated photoemitters. Using an argon-ion laser irradiating wavelength of 488 nm, 2.5 mA of current, at a current density of 80 mA/sq cm, was drawn.