S. K. Lyubutin

Novel nanosecond semiconductor opening switch for megavolt repetitive pulsed power technology: experiment and applications

A novel nanosecond semiconductor opening switch (SOS) has been developed which has a pulsed power of the GW range and voltage levels of up to a few 100s of kV. The SOS is based on high-voltage solid state rectifiers and is designed for pulsed power generators with inductive energy storage. A 30 ns opening phase duration, a 45 kA interrupted current, and a 450 kV opened SOS voltage have been attained with the use of a three-stage, 2 kJ, 150 kV open circuit Marx generator as the SOS driver. On the basis of the experimental results obtained, we have developed and tested repetitive high-current generators and accelerators with a 0.5 MV output voltage and a 15 to 100 ns pulse width. The ideology is presented of constructing high-power megavolt pulsed generators with an all-solid- state switching system. A description is provided of the setups developed on this principle. We discuss features peculiar to the setups developed and prospects of developing these further.

Repetitive nanosecond all-solid-state pulsers based on SOS diodes

The paper describes design and technical specifications of nanosecond high-voltage pulsed generators that have an all-solid-state switching system. As a final power amplifier the semiconductor opening switch (SOS) and an inductive store are used. The devices present desktop hand-carried units that are capable of delivering to a load pulses with the following parameters: voltage 110 to 450 kV; current 0.4 to 1.5 kA; pulse width 20 to 40 ns; continuous pulse repetition rate 100 to 1000 pps; and burst mode up to 5000 pps.

Generation of gigawatt 10-GHz pulses with stable phase

The generation of microwave pulses in a 10-GHz range has been studied in a nonstationary relativistic backward wave oscillator (BWO) operating at a pulse train repetition rate of up to 300 Hz. Regimes with a stabilized phase of the high-frequency filling of pulses with respect to the accelerating voltage pulse front have been observed at a BWO peak output power of ∼1 and 3 GW. In pulse trains with a length of 10–100 s, the average output microwave power reached ∼1 kW.

High peak power and high average power subnanosecond modulator operating at a repetition frequency of 3.5 kHz

This paper presents results of tests of a hybrid subnanosecond modulator with an output resistance of 45 /spl Omega/. The modulator comprises an all-solid-state nanosecond charger, which is equipped with an inductive energy store and a semiconductor opening switch, and a pulse peaker with hydrogen spark gaps. The modulator generates stable pulses-(180 to 200) kV in amplitude and 400 to 700 ps long at a pulse repetition rate of up to 3.5 kHz. An average output power of 1.5 kW was achieved under the pulse burst mode.

Semiconductor opening switch research at IEP

This paper describes the physical principles of operation of semiconductor opening switches (SOS). The SOS effect occurs at a current density of up to 60 kA/cm/sup 2/ in silicon p/sup +/-p-n-n/sup +/ structures filled with residual electron-hole plasma with the concentration between 10/sup 16/ and 10/sup 17/ cm/sup -3/. On the basis of a theoretical model developed for plasma dynamic calculation the mechanism by which the current passes through the structure at the stage of high conduction and the processes that occur at the stage of current interruption have been investigated. Dynamics of the electron-hole plasma were calculated with allowance for real distribution of impurity doping in the structures. Experimentally obtained current density-time, and current density-interruption time dependencies of semiconductor opening switches are discussed. Applications of the SOS effect in pulsed power is also be demonstrated.

Ultrafast current switching using the tunneling-assisted impact ionization front in a silicon semiconductor closing switch

Ultrafast current switching in semiconductors, based on the mechanism of tunneling-assisted impact ionization front, has been experimentally implemented and theoretically studied. A voltage pulse with an amplitude of 220 kV and a front duration of 1 ns was applied to a semiconductor device containing 20 serially connected silicon diode structures. After switching, 150-to 160-kV pulses with a power of 500 MW, a pulse duration of 1.4 ns, and a front duration of 200–250 ps were obtained in a 50-Ω transmission line. The maximum current and voltage buildup rates amounted to 10 kA/ns and 500 kV/ns, respectively, at a switched current density of 13 kA/cm2. The results of numerical simulation are presented, which show that the current switching is initiated at a threshold field strength of about 1 MV/cm in the vicinity of the p-n junction, where the tunneling-assisted impact ionization begins.

Solid-State SOS-Based Generator Providing a Peak Power of 4 GW

This paper describes a high-current nanosecond generator providing peak power of up to 4 GW, output voltage of 0.4-1 MV, pulse length of 8-10 ns, and pulse repetition rate of 300 Hz in the continuous mode and up to 1 kHz in the burst mode of operation. The average output power is up to 30 kW at a pulse repetition rate of 1 kHz. The generator is outfitted with an all-solid-state system of energy switching. The output pulse is formed by semiconductor opening switch diodes. The electric circuit and the design of the generator have been described. Experimental results have been given. A device for the elimination of prepulses across the load has been proposed. Testing results and numerical modeling of the device have been reported

Repetitive 200 kV nanosecond all solid state pulser with a semiconductor opening switch

A compact 200 kV, 1 kA, 40-50 ns, 30-300 pps pulser has been developed. A distinctive feature of this pulser is that it uses an all solid state switching system. As a final power amplifier the semiconductor opening switch (SOS) is used. After the SOS has operated at a load of 220 /spl Omega/, a 215 kV pulse is formed which has a half-height duration of /spl sim/40 ns. The pulse energy is about 6 J. At the pulse repetition rate of up to 300 pps the instability of the output pulse parameters is tenths of a percent and is determined by the instability of the input supply voltage. The dimensions of the pulser are 650/spl times/600/spl times/320 cub. mm, it weighs /spl sim/80 kg. The pulser developed can be instrumental in conducting research aimed at searching for and refining novel technologies under laboratory conditions.

Operation of a semiconductor opening switch at ultrahigh current densities

The operation of a semiconductor opening switch (SOS diode) at cutoff current densities of tens of kA/cm2 is studied. In experiments, the maximum reverse current density reached 43 kA/cm2 for ∼40 ns. Experimental data on SOS diodes with a p+-p-n-n+ structure and a p-n junction depth from 145 to 180 μm are presented. The dynamics of electron-hole plasma in the diode at pumping and current cutoff stages is studied by numerical simulation methods. It is shown that current cutoff is associated with the formation of an electric field region in a thin (∼45 μm) layer of the structure’s heavily doped p-region, in which the acceptor concentration exceeds 1016 cm−3, and the current cutoff process depends weakly on the p-n junction depth.

Ultra-high-power repetitive solid state DBD-based switching

A delayed breakdown device (DBD) presents a closing switch employing the process of fast filling of the semiconductor structure with plasma produced by an ionizing shock wave. The DBD-effect was discovered by I.V. Grekhov and A.F. Kardo-Sysoev in 1979. Today the most powerful DBDs containing several series-connected semiconductor structures form pulses with amplitude of about 10/sup 4/ V and a peak power of units of MW at a 50-/spl Omega/ load. We tried to extend the DBD-based switching process to output voltages equal to hundreds of kV and an output power of several hundreds of MW by connecting many large-square structures in series. The experiments showed that this approach permits increasing the peak power by more than two orders of magnitude (up to 1 GW) at the FWHM of about 2 ns.