Experimental demonstration of a single capillary, water-activated cathode for a sub-microsecond electron accelerator

A pulsed electron beam is a modern tool for research and technology. The parameters of the electron beam depend on the characteristics of the cathode system. This paper describes the first results of tests of novel type of a plasma cathode for a sub-microsecond electron accelerator. The cathode supplies ∼1.5 mg/s of distilled water through a single capillary to the accelerating gap. A generator based on a pulsed transformer supplies 300 kV, 200 ns (FWHM) voltage pulses at repetition rate of up to 40 pps to the vacuum diode and produces an electron-beam current of 250 A. Optical imaging of the cathode surface definitely localizes the emission center at the location of the single capillary. A single pulse of the electron beam transmits ∼38 μC of charge and ∼6.5 J of energy.