Picosecond solid-state generator with a peak power of 50 GW.

This article describes a picosecond solid-state pulsed system, where the input pulse from the generator with a semiconductor opening switch (SOS) is amplified in power and decreases in duration by ferrite gyromagnetic lines. The lines operate in the Magnetic Compression Line (MCL) mode, which occurs at close values of the input pulse duration and the period of the oscillations generated in the line. The energy compression system contains three successive stages-MCL1-MCL3 lines. For an input pulse power of 6 GW (490 kV, 40 Ω) and a duration of 7 ns, pulses of 54 GW (1.62 MV, 48 Ω) and a duration of 170 ps have been achieved at the MCL3 output. Compared to the parameters of the input pulse, the voltage rise rate has been increased ∼130 times up to 14.8 MV/ns, and the power rise rate has been increased ∼350 times up to 0.7 TW/ns. A numerical simulation of the MCL3 line operation in which the maximum electric and magnetic fields are realized (>2 MV/cm and >500 kA/m, respectively) has been carried out. The inner structure of the process of power amplification during the electromagnetic wave passage along the line has been demonstrated. First, the front of the input pulse is sharpened, and then, after the excitation of the oscillations, the process of power amplification begins, followed by the pulse amplitude reaching the saturation region.

Pulsed power technology based on semiconductor opening switches: A review.

This paper presents a systematized review of the research on the production of nanosecond high-power pulses using solid-state generators based on an inductive energy store and a semiconductor opening switch that have been performed in the past 25 years. This research has been underway since 1992-1993 when the nanosecond cutoff of ultrahigh-density currents in semiconductor diodes was discovered and named the SOS (Semiconductor Opening Switch) effect. The discovery of the SOS effect provided a breakthrough in the development of semiconductor generators, as their most important characteristics, such as pulse power and output voltage, were increased tens and hundreds of times compared with previously known semiconductor generators. In particular, in the nanosecond semiconductor technology, megavolt voltages combined with gigawatt peak powers have been achieved. This review considers the main physical processes that determine the mechanism of operation of a SOS based on the SOS effect. The principle of operation, design, and characteristics of SOS diodes and SOS generators is described, and prospects for their further development are discussed. Examples are given of using SOS generators in various pulsed power applications such as electron accelerators, X-ray pulse devices, high-power microwave electronics, pumping of gas lasers, and ignition of electrical discharges.

Four-channel generator of 8-GHz radiation based on gyromagnetic non-linear transmitting lines.

Test results of high-voltage one- and four-channel radio-frequency (RF) generators based on the coaxial gyromagnetic ferrite-filled nonlinear transmission lines (NLTL) with external magnetic bias and RF-modulation frequency of a high-voltage pulse envelope of ∼8 GHz are presented. Electrical strength of oil-isolated NLTLs was tested in a compact version of one-channel generator based on the RADAN driver at a repetition rate of 100 pps. In case of a stationary setup, 5-ns pulse with -500 kV amplitude was split into 4 channels with individual NLTLs. Gyromagnetic line output pulses had fast damped RF-modulation with a maximum modulation depth more than 50% and the peak amplitude of -200 kV. Independent control of a delay time in each channel was realized by the coaxial spiral lines with a central biased ferrite core. The coherent summation possibility of RF fields in the free space radiated by a 4-channel system of conical dielectric antennas was demonstrated.

Semiconductor opening switch generator with a primary thyristor switch triggered in impact-ionization wave mode.

The results of the investigation involving a thyristor switch triggered in the impact ionization wave mode are presented. This switch is intended for operation as a primary switch in a nanosecond pulse generator with a semiconductor opening switch (SOS). The thyristor switch is based on commercial low-frequency tablet thyristors stacked in a joint assembly of up to 6 pieces connected in series. At a charging voltage of 2-12 kV and switching energy of up to 16 J, the switch operates with a discharge current of up to 8 kA, a current rise rate in the range from 14 to 54 kA/µs, and a switching efficiency of ∼0.9. It is shown that an increase in a voltage rise rate on thyristors at the triggering stage reduces energy loss in the thyristor switch during the current flow. The SOS pumping circuit contains one magnetic element-a pulse transformer, which simplifies the generator and increases its efficiency. The SOS generator has an output voltage of up to 300 kV and a peak power of up to 250 MW with a pulse duration of ∼50 ns. The thyristor switch in the generator operates at a voltage of 12 kV and provides current flow with the amplitude of up to 7.5 kA with a duration of ∼500 ns and a current rise rate of ∼54 kA/µs. The pulse repetition frequency of the generator is 1 kHz in the burst mode of operation.

A 30 GW subnanosecond solid-state pulsed power system based on generator with semiconductor opening switch and gyromagnetic nonlinear transmission lines.

This article describes a subnanosecond solid-state pulsed power system in which an input pulse from a generator with a semiconductor opening switch (generator) is amplified in power and is shortened in time by a two-stage magnetic compressor based on gyromagnetic nonlinear transmission lines. In this approach, the line of each stage operates as a magnetic compression line (MCL) which is realized when the duration of the input pulse is close to the period of oscillations generated by the line. The compression system contains two series connected lines MCL1 and MCL2 with a wave impedance of 40 Ω. The input pulse has a duration of 7 ns and an amplitude of 500 kV. After two compression stages, the pulse amplitude increases to 1.1 MV and the peak power increases from 6 to 30 GW, while the pulse duration transits into subnanosecond range (0.65 ns). In the burst mode, the system operates at a pulse repetition frequency up to 1 kHz.

Semiconductor sharpeners providing a subnanosecond voltage rise time of GW-range pulses.

The article describes semiconductor sharpeners providing a subnanosecond voltage rise time of GW-range pulses. The sharpeners are made as stacks of series-connected dynistor structures built into an oil-filled coaxial line with 48 Ω wave impedance at the place of an inner conductor. Two sequential sections of pulse sharpening are used. An input voltage pulse has the amplitude of 540 kV with the rise time of ∼1.2 ns at 0.2-0.9 level from the amplitude 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. The sharpeners are tested at a pulse repetition frequency of up to 1 kHz. Sharpener operation is studied by numerical simulation methods. Experimental waveforms of output pulses and the corresponding calculated voltage-time dependences are in statistical agreement.

Solid-state repetitive generator with a gyromagnetic nonlinear transmission line operating as a peak power amplifier.

In this work, experiments were made in which gyromagnetic nonlinear transmission line (NLTL) operates as a peak power amplifier of the input pulse. 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. Power amplification is achieved due to the voltage amplitude of the first peak across the NLTL output exceeding the voltage amplitude of the input pulse. In the experiments, the input pulse with an amplitude of 500 kV and a half-height pulse duration of 7 ns is applied to the NLTL with a natural oscillation frequency of ∼300 MHz. 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. As a source of input pulses, a solid-state semiconductor opening switch generator was used, which allowed carrying out experiments at pulse repetition frequency up to 1 kHz in the burst mode of operation.

Four channel high power rf source with beam steering based on gyromagnetic nonlinear transmission lines.

The synchronized operation of four gyromagnetic nonlinear transmission lines (NLTLs) was tested with a pulse repetition frequency up to 1 kHz during 1 s bursts. High voltage pulses with a duration of ∼5 ns from the solid state driver S-500 were split into four 48 Ω channels reaching about -200 kV in each channel with ∼10% variation in the amplitude. The maximum peak voltage at the NLTL output was within 220-235 kV with the maximum modulation depth of decaying oscillations up to 90% at the center frequency near 2.1 GHz. The relative delay between channels reached the half-period of the center frequency of oscillations. The associated beam steering by four element array of conical helical antennas was demonstrated in a horizontal plane at 17°. The effective potential of radiation reached 360 kV at the radiation axis. The effect of ferrite temperature on the shock wave velocity in gyromagnetic NLTL is observed.

A 6 GW nanosecond solid-state generator based on semiconductor opening switch.

In this paper, a nanosecond all solid-state generator providing peak power of up to 6 GW, output voltage of 500-900 kV, pulse length (full width at half maximum) of ∼7 ns across external loads of 40-100 Ω, and pulse repetition frequency up to 1 kHz in burst operation mode is described. The output pulse is generated by a semiconductor opening switch (SOS). A new SOS pumping circuit based on a double forming line (DFL) is proposed and its implementation described. As compared with a lumped capacitors-based pumping circuit, the DFL allows minimization of the inductance and stray capacitance of the reverse pumping circuit, and thus, an increase in the SOS cutoff current amplitude and generator output peak power as a whole. The pumping circuit provides a reverse current increasing through the SOS up to 14 kA within ∼12 ns. The SOS cuts off the current in ∼2 ns; the current cutoff rate reaches 7 kA/ns. The SOS braking power (the product of peak voltage and cutoff current) for an external load above 100 Ω is 13 GW.

Generation of electromagnetic fields of extremely high intensity by coherent summation of Cherenkov superradiance pulses.

We demonstrate both theoretically and experimentally the possibility of correlating the phase of a Cherenkov superradiance (SR) pulse to the sharp edge of a current pulse, when spontaneous emission of the electron bunch edge serves as the seed for SR processes. By division of the driving voltage pulse across several parallel channels equipped with independent cathodes we can synchronize several SR sources to arrange a two-dimensional array. In the experiments carried out, coherent summation of radiation from four independent 8-mm wavelength band SR generators with peak power 600 MW results in the interference maximum of the directional diagram with an intensity that is equivalent to radiation from a single source with a power of 10 GW.

High repetition rate multi-channel source of high-power rf-modulated pulses.

This paper presents the results of testing a high voltage pulse generator based on parallel gyromagnetic nonlinear transmission lines filled with saturable ferrite. The generator is capable of producing almost identical stable rf-modulated nanosecond high voltage pulses in each of the two, or four, parallel output channels. The output voltage amplitude in each channel can reach -285 or -180 kV, respectively, with a rf modulation depth of up to 60%. Drive pulses were produced as the packets of duration 1-5 s at a pulse repetition frequency of 800 Hz using a driver equipped with all-solid-state switches. Splitting the driver pulse provided electric field strengths in the channels which were below the breakdown field strength of the transmission lines. As a result, the use of nonlinear transmission lines of reduced diameter made it possible to increase the center frequency of the excited rf oscillations to ∼2 GHz.