Solid-state repetitive generators of short GW-range pulses: a review

Abstract

The paper presents a brief review of solid-state repetitive generators of nano- and subnanosecond pulses with GW-range of peak power developed by Institute of Electrophysics. The base of the described approach for obtaining such pulses consists in using solid-state generators with its output unit containing intermediate inductive storage and semiconductor opening switch (SOS). The most powerful SOS generator of S-500 type is described. The generator provides a peak power of up to 6 GW, an output voltage of 500–900 kV, a voltage rise time of 2–3 ns, a pulse length (full width at half maximum, FWHM) of 5–7 ns across external loads of 40–100 Ω, and a pulse repetition frequency up to 1 kHz in the burst mode of operation. To reduce the voltage rise time of S-500 generator semiconductor sharpeners are used. The sharpeners are made as stacks of series-connected dynistor structures built into an oil-filled coaxial line at the place of an inner conductor. An input voltage pulse has the amplitude of 540 kV with the rise time of ∼1.2 ns and voltage rise rate of ∼0.3 MV/ns. After pulse propagation through the sharpening sections, its rise time is reduced down to 360 ps, and the voltage rise rate is increased up to ∼0.95 MV/ns. Peak power of the sharpened pulse is within the range of 4.5–5.5 GW. It is shown, that gyromagnetic nonlinear transmission line (NLTL) can operate as a magnetic pulse compressor. At such an operating regime, the duration of the input pulse is close to the period of generated oscillations, and the main part of the input pulse energy is transmitted only to the first peak of the oscillations. In energy compression experiments, the input pulse with amplitude of 500 kV and FWHM of 7 ns is applied to the NLTL. At the output of the NLTL in 40 Ω coaxial transmission line, the pulse amplitude is increased to 740 kV and the pulse duration is reduced to ∼2 ns, which correspond to power amplification of the input pulse from ∼6 to ∼13 GW. In pulse sharpening experiments, a three-stage NLTL is used. The system provides a peak power of 15 GW in 44-Ω line, FWHM of 120 ps, and a record high level of the voltage rise rate of 10 MV/ns. Applications of the developed generators are given.