Nanosecond pulser thyratons

A modified version of the HY-3013L thyratron has demonstrated substantially greater voltage holdoff and reduced triggering requirements. New recovery measurements, with circuitry designed to eliminate false triggering of the pulsed voltage sources, have yielded de-ionization times well within the 50 microsec required for 20kHz operation, at voltages and pressures well beyond those needed to meet the load voltage rise time and pulse width requirements. An instant-start dispenser cathode suitable for use with HY-3013L-type thyratrons has been developed and tested successfully in similar tubes. An ultra low inductance PFN/load combination has been constructed, and has produced a smooth 3.5ns FWHM multi-kilovolt pulse across a nominal 50pf load capacitance when switched via a short air gap. The kapton capacitors and ceramic resistor load shunt are theoretically capable of operating at around 200 watts average power. Three saturable reactor materials have been evaluated theoretically: orthonol, metglas and ferrite. Of these, only ferrite appears usable on a 10ns time scale, metglas and orthonol being unsuitable because of their low resistivity. Finally, a 20kHz kit has been constructed for high prr testing of the assembled nanosecond pulser circuit.