Generation of high-current electron beams by the use of plasma cathodes

In this report we present experimental data concerning the use of various plasma sources to generate high-power, high-current electron beams in a repetitive mode instead of explosive emission plasma. The concept of this research is in the plasma creation prior to the application of the acceleration voltage to the anode-cathode gap, and in the achievement of the condition when the space-charge limiting electron current density is equal to the electron plasma saturation current density. It has been shown that it is possible to generate electron beams without creation of explosive plasma and without the time delay with respect to the beginning of the acceleration voltage. This can be achieved by the proper adjustment of the plasma parameters to the diode geometry and to the amplitude of the acceleration voltage. Experimental results of generation of electron beams with current density of 100 A/cm/sup 2/, and electron energy of 40 kV continuously with repetition rate of 2 Hz are presented.