Subnanosecond modulator possessing a 700 MW peak power and average power of 1.5 kW at repetition frequency of 3.5 kHz

Summary form only given, as follows. Applications of high-power, ultrawideband electromagnetic pulse generators and superradiative microwave oscillators producing broadband millimeter-wavelength spikes call for subnanosecond pulsewidth modulators providing both high peak power and high PRF. The paper presents new results of tests of repetitive subnanosecond modulator which combines a solid-state nanosecond driver based on an inductive energy store with a semiconductor opening switch and a pulse shaper based on ultrahigh-pressure hydrogen spark gaps. A SM-3NS solid-state driver is a system consisting of several capacitive energy stores, a pulse transformer, and saturable magnetic switches. The output stage of energy compression includes an inductive store and a high-current semiconductor opening switch. As this switch operates, a voltage of over 450 kV with a pulse duration of 5 ns is generated at the open output of the driver. The driver provides a packet operation of the modulator with a PRF of up to 3.5 kHz. In producing of subnanosecond pulses, this driver is used to charge a short pulse-forming line with a wave impedance of 50 Ohm and a capacitance of /spl sim/10 pF. The highest charging voltage achieved was 400 kV. Short bell-type or quasi-rectangular pulses (leading edge of 180 ps; width of 0.35-1 ns, amplitude of 180-200 kV) were formed by operation of sharpening and chopping spark gaps filled with hydrogen (100 atm). The modulator was tested for operation at PRF of up to 3,500 Hz. Forced circulation of the working gas was not used. The data are given for hydrogen on the decrease in breakdown voltage with increasing pulse repetition rate, the stability of the breakdown voltage, and the time delay of the breakdown of the chopping gas gap relative to that of the sharpening gas gap.