A Megavolt Nanosecond Generator with a Semiconductor Opening Switch

A high-current nanosecond-pulse generator with a pulse power of up to 1.6 GW, an output voltage of 0.5–1 MV, pulse duration of 40–60 ns, and repetition rates of 300 Hz (in a steady-state mode) and up to 850 Hz (in a burst mode) is described. Its average output power is 30 kW at a pulse repetition rate of 500 Hz. The energy-switching system of the generator fully consists of solid-state elements: a thyristor, magnetic switches, and a semiconductor-opening switch based on SOS diodes.     

A nanosecond SOS generator with a peak power of 4 GW

A high-current nanosecond generator with a peak power of up to 4 GW, an output voltage of 0.4–1 MV, a pulse duration of 8–10 ns, and pulse repetition rates of 300 Hz in a continuous mode and up to 1 kHz in the burst mode is described. The average output power at a pulse repetition rate of 1 kHz reaches 30 kW. The generator has an all-solid-state energy-switching system. A semiconductor opening switch on SOS diodes forms output pulses. The electric circuit and design of the generator are described, and the experimental results are presented. A device for eliminating prepulses across the load is proposed. The results of its testing and numerical simulation are presented.     

A high-power nanosecond pulse generator based on solid-state switches

A high-power nanosecond pulse generator based on a Lewis transformer and ultrafast IGBT-transistors is described. The generator ensures the formation of square pulses at a 50-Ω matched load with a repetition rate of up to 2 kHz. The pulse duration may be freely varied from 20 to 200 ns, and the pulse power may vary from 200 W to 2 MW.     

A generator of high-power nanosecond pulses based on a modular two-level summator

A modular approach to designing generators of high-power high-voltage nanosecond pulses on the basis of a two-level wave summator and transistor formers of partial pulses is considered. The design and parameters of the modules that are oriented at the development of generators of voltage pulses of up to 300 kV at a current of up to 4 kA are described. The capabilities of these modules are demonstrated based on the example of a pulse generator with a power of 10 MW, a varied pulse duration of 50–150 ns, and a pulse repetition rate of up to 2 kHz.     

Studying the pulse responses of semiconductor detectors at the SPIN-2 accelerator

Responses of ДППД1, ДППД2, and ДАД1 semiconductor dosimetric detectors to a subnanosecond pulse of the SPIN-2 accelerator were investigated. The pulse response of the register channel was investigated using an И1–12 voltage drop generator with a rise time of 0.05 ns. The duration of the pulse responses of the register channel was estimated to be t _1/2 = 0.19 ns and that of an RTO1044 oscilloscope was t _1/2 = 0.17 ns. The duration of the response of the electron detector with the running wave to the SPIN-2 pulse was t _1/2 = 0.22 ns. The response durations of the ДППД1 and ДППД2 detectors to X-ray pulses were 0.80 and 0.55 ns, respectively. The response durations of ДАД1 diamond detectors were in the range of 0.28–0.40 ns. The restored ДАД1 pulse responses were 0.15–0.30 ns.     

A compact semiconductor opening swith-based generator with a 300-kV output voltage and up to 2-kHz pulse repetition rate

A compact generator with a semiconductor opening switch (SOS-diode) shaping across resistive load pulses with an amplitude of up to 300 kV, duration of 30–50 ns, and a 300-Hz pulse repetition under uninterrupted operation and up to 2 kHz in a 30-s burst mode is described. The generator contains a thyristor charging device, magnetic compressor, and inductive storage with a semiconductor opening swith based on SOS-diodes. The average output power at a maximum pulse repetition rate and a 250kV-voltage is 16 kW. The overall dimensions of the generator are 0.85×0.65×0.42 m, the weight is about 115 kg.     

High-frequency pulse generators based on SOS diodes with subnanosecond current cutoff time

Compact high-voltage generators with a pulse power of 100–500 MW, an output voltage of 150–400 kV, a pulse duration of 3–6 ns, and pulse repetition rates of 300–400 Hz and up to 5 kHz in a steady-state and a 30-s-long burst mode, respectively, are described. The output power-amplification unit is based on an inductive storage and SOS diodes with subnanosecond current cutoff time. Physical processes in the semiconductor structure of a SOS diode operating in the subnanosecond current cutoff mode are considered. The generator circuit designs and their test results are presented.     

200 ns pulse high-voltage supply for terahertz field emission

We present a method of generating 200 ns high-voltage (up to 40 kV) pulses operating at repetition rates of up to 100 kHz, which may be synchronized with laser pulses. These supplies are simple to make and were developed for ultrafast terahertz pulse generation from GaAs photoconductive antennas using a high-repetition-rate regeneratively amplified laser. We also show an improvement in signal-to-noise ratio over a continuous dc bias field and application of the supply to terahertz pulse generation.     

Experimental studies of scintillation detectors based on WLS fibers

This paper describes the design and presents the results of experimental studies of single-stage and two-stage fiber-optic light collection (FOLC) scintillation detectors based on wavelength-shifting (WLS) fibers. FOLC detectors are designed for the registration of ionizing radiation with a pulse duration of up to 20 μs. The detector design allows one to place photodetectors at a distance of up to tens of meters from the scintillator. The time resolution and sensitivity of FOLC detectors to ⁶⁰Co gamma photons were studied. Experimental studies of FOLC detectors were performed at FSUE All-Russia Research Institute of Automation (VNIIA).     

Note: a high performance pulse energy detector for Q-switched laser based on photoacoustic effect

A high performance pulse energy detector is developed based on photoacoustic effect. Different from the detectors reported before which also utilized photoacoustic effect, our detector can measure the energy of each pulse output from a Q-switched laser and monitor the pulse energy fluctuation in real time owing to the signal processing circuit designed. By comparing with a commercial laser energy meter, our detector is proved to be of high sensitivity and accuracy. We test the detector under illumination of different pulse energy at varied wavelengths, and the results demonstrate that the detector has a broad spectral response and a dynamical energy range. Besides, the measurements of this detector will not be affected by the background light according to the principle of photoacoustic effect.     

Detection of nanosecond-scale, high power THz pulses with a field effect transistor

We demonstrate detection and resolution of high power, 34 ns free electron laser pulses using a rectifying field effect transistor. The detector remains linear up to an input power of 11 ± 0.5 W at a pulse energy of 20 ± 1 μJ at 240 GHz. We compare its performance to a protected Schottky diode, finding a shorter intrinsic time constant. The damage threshold is estimated to be a few 100 W. The detector is, therefore, well-suited for characterizing high power THz pulses. We further demonstrate that the same detector can be used to detect low power continuous-wave THz signals with a post detection limited noise floor of 3.1 μW/√Hz. Such ultrafast, high power detectors are important tools for high power and high energy THz facilities such as free electron lasers.     

LED source for determining optical detector time response at 1.06 microm

A gallium indium arsenide light emitting diode (LED) is investigated as a source for determining optical detector time response at 1.06 microm. To obtain either impulse or step-shaped waveforms, the diode is driven by a charged transmission line switched by a transistor operating in the avalanche mode. A pulse with a 2.5-ns full width at half-maximum and a step with a 3-4-ns transition time are produced at repetition rates to 1 kHz. The effects of wavelength change during the pulse (chirping) are discussed and evaluated.     

Operating features of a high-voltage spark gap switch with gas blow normal to the breakdown path in a repetitively pulsed mode

The results of studies of a high-voltage two-electrode spark gap switch (SGS) with forced gas blow at an operation voltage of up to 1.2 MV are presented. An SGS filled with nitrogen as the working gas at a pressure of up to 16 atm operated as the high-voltage switch of a high-current nanosecond electron accelerator. The gas flow was directed normally to the breakdown path. The SGS switched a 50-Ω forming line with an electrical length of 10 ns to a matched load. The voltage rise time across the electrodes before breakdown was ～25µs. A stable repetitively pulsed mode is realized at operating voltages of 100–680 kV and pulse repetition rates of up to 270 Hz with a standard deviation of the pulse breakdown voltage of ≤1%. The physical mechanisms that determine unstable operation of the device during self-breakdown are analyzed.     

A phoswich detector for β-ray spectrometry

The spectrometric characteristics of a scintillation phoswich detector for β-ray spectrometry are described. The phoswich detector is composed of two detectors, one of which is an inorganic scintillator (calcium chlorborate) and the other is a scintillating plastic. The background of this phoswich detector is a factor of 9.3 lower than that of a single detector based on a plastic scintillator. At the same time, the dependence of its pulse heights on the β-particle energy is shown to be linear.     

A high-voltage semiconductor rectangular-pulse generator for powering a barrier discharge

A semiconductor rectangular-pulse generator with smoothly controlled output parameters for powering a barrier discharge was developed and investigated. The generator allows the formation of voltage pulses with the smoothly regulated amplitude (0–16 kV) and duration (600 ns–1 ms) across the discharge gap. The pulse rise and fall times can be varied from 40 ns to 1 μs. The generator pulse repetition rate can be smoothly varied from 0 to 50 kHz. The generator can operate in the manual-triggering mode and in the mode of pulse trains with an effective frequency of up to 500 kHz. The generator is intended for initiating and investigating a barrier discharge in millimeter-wide air gaps at the atmospheric pressure.     

Magnetotransistor generator for powering a copper vapor laser

A generator designed to excite a copper vapor laser is described. A high-voltage switch used in the generator circuit is based on ten IGBT transistors connected in series and operates jointly with two sections of magnetic pulse compression. A Kulon LT-10Cu sealed-off and self-heated gas-discharge tube with an average consumed power of 1.4 kW is used as an active element. The maximum power emitted by the active element is 13 W, at which the amplitude of the current flowing through this element is 180 A, the pulse duration at the base is 100 ns, and the pulse repetition rate is 17 kHz.     

Formation of subnanosecond rise times of high-voltage pulses in an unsaturated-ferrite-loaded coaxial line

A high-voltage forming device in which a section of a ferrite-filled coaxial transmission line is used to sharpen the rise time of nanosecond pulses has been studied. It is shown that low-conductivity nickel-zinc ferrites are suitable for sharpening the rise time of submegavolt pulses. Experiments for two versions of the ferrite line and different lengths of the ferrite-filled sections have been performed. The experimental results indicate the possibility of sharpening the rise time of output pulses to 0.7 ns in the range of pulse amplitudes 110–360 kV at a pulse repetition rate of up to 100 Hz.     

Application of the TPI1-10k/50 thyratron in a frequency mode for pumping gas lasers

The design of a TPI1-10k/50 thyratron-based modulator, powering a gas laser tube with a 50-cm length, 5-cm diameter, pulse repetition rate of up to 5 kHz, current of up to 7 kA, voltage of up to 10 kV, and half-height current pulse length of 23–25 ns is described. The test results demonstrating that it is possible to use this thyratron for pumping gas lasers in the frequency mode are presented.     

A SOS-Generator for technological applications

A solid-state nanosecond SOS-generator for electrophysical technology applications is described. In the input part of the generator, the energy arrives at the high-voltage magnetic compressor through IGBT modules and a step-up pulse transformer. The input part of the generator is equipped with an unused energy recuperation circuit, and, when the output pulse is formed, the microsecond pumping mode of the semiconductor opening switch (SOS) is realized. As a result, the complete efficiency of the generator operating into a matched load is increased from ∼40 to 60–62%. The other characteristics of the generator are as follows: the peak voltage is up to 60 kV, the current is up to 6 kA, the pulse duration is about 40 ns, the pulse repetition rate in the continuous mode is 1 kHz, and the average output power is up to 9 kW.     

A high-voltage pulse generator for electric-discharge technologies

The electric circuit and design of a high-volta ge pulse generator with an output voltage of ≥3 50 kV is described. The generator operates in the nanosecond range of pulse durations (~300 ns) at a repetition rate of up to 10 pulses/s in a continuous mode and is intended for electric-discharge technologies. The energy stored in the generator is ~600 J, and the energy released in a pulse is ≥300 J. A discharge of a capacitive storage through a toroidal pulsed transformer and a discharge gap is used in the generator.