A trigger generator for controlling a high-current triggered vacuum switch

A trigger generator (TG) with a discharge of a storage capacitor through the trigger gap of a triggered vacuum switch (TVS) was developed. It provides a voltage amplitude of up to 7 kV across the trigger gap. After a gap breakdown, the TG provides an ignition current in the form of a damped sinusoid with an amplitude of ≥1 kA. It differs from analogous devices by pulsed charging of the storage capacitor and the use of an output self-breakdown gas-filled switch. The developed design of the gas switch with gas preionization in the spark gap by an additional corona discharge provides high stability of both the pulsed-breakdown voltage and the switching-on time. The TG tests showed reliable and stable switching-on of high-current TVSs of different modifications with a discharge-current rise rate of up to 3 × 10¹⁰ А/s.     

A compact, low jitter, nanosecond rise time, high voltage pulse generator with variable amplitude

In this paper, a compact, low jitter, nanosecond rise time, command triggered, high peak power, gas-switch pulse generator system is developed for high energy physics experiment. The main components of the system are a high voltage capacitor, the spark gap switch and R = 50 Ω load resistance built into a structure to obtain a fast high power pulse. The pulse drive unit, comprised of a vacuum planar triode and a stack of avalanche transistors, is command triggered by a single or multiple TTL (transistor-transistor logic) level pulses generated by a trigger pulse control unit implemented using the 555 timer circuit. The control unit also accepts user input TTL trigger signal. The vacuum planar triode in the pulse driving unit that close the first stage switches is applied to drive the spark gap reducing jitter. By adjusting the charge voltage of a high voltage capacitor charging power supply, the pulse amplitude varies from 5 kV to 10 kV, with a rise time of <3 ns and the maximum peak current up to 200 A (into 50 Ω). The jitter of the pulse generator system is less than 1 ns. The maximum pulse repetition rate is set at 10 Hz that limited only by the gas-switch and available capacitor recovery time.     

High-voltage pulsed generator for dynamic fragmentation of rocks

A portable high-voltage (HV) pulsed generator has been designed for rock fragmentation experiments. The generator can be used also for other technological applications. The installation consists of low voltage block, HV block, coaxial transmission line, fragmentation chamber, and control system block. Low voltage block of the generator, consisting of a primary capacitor bank (300?μF) and a thyristor switch, stores pulse energy and transfers it to the HV block. The primary capacitor bank stores energy of 600 J at the maximum charging voltage of 2 kV. HV block includes HV pulsed step up transformer, HV capacitive storage, and two electrode gas switch. The following technical parameters of the generator were achieved: output voltage up to 300 kV, voltage rise time of ～50?ns, current amplitude of ～6?kA with the 40?Ω active load, and ～20?kA in a rock fragmentation regime (with discharge in a rock-water mixture). Typical operation regime is a burst of 1000 pulses with a frequency of 10 Hz. The operation process can be controlled within a wide range of parameters. The entire installation (generator, transmission line, treatment chamber, and measuring probes) is designed like a continuous Faraday's cage (complete shielding) to exclude external electromagnetic perturbations.     

A compact nanosecond pulse generator

A compact high-current pulse generator with the amplitude of the load current up to 140 kA and rise time below 200 ns is designed. The basic element of the pulse generator design is the HCEIcap 100–0.2 capacitor switch assembly. The capacitance value of the capacitor switch assembly is 200 nF, the charging voltage is 100 kV, the energy storage is 1000 J, and the full inductance value is 20 nH. The sizes of the active part of the capacitor are 80-mm inner diameter ×160-mm outer diameter ×160 mm. A multigap spark-gap is used as a switch. The rise rate of the current through the load (X-pinch, 2 molybdenum wires with a 25-μm diameter) is 1.3 kA/ns, and the soft X-ray pulse duration is 2.0–3.5 ns.     

Design and performance of a pulse transformer based on Fe-based nanocrystalline core

A dry-type pulse transformer based on Fe-based nanocrystalline core with a load of 0.88 nF, output voltage of more than 65 kV, and winding ratio of 46 is designed and constructed. The dynamic characteristics of Fe-based nanocrystalline core under the impulse with the pulse width of several microseconds were studied. The pulse width and incremental flux density have an important effect on the pulse permeability, so the pulse permeability is measured under a certain pulse width and incremental flux density. The minimal volume of the toroidal pulse transformer core is determined by the coupling coefficient, the capacitors of the resonant charging circuit, incremental flux density, and pulse permeability. The factors of the charging time, ratio, and energy transmission efficiency in the resonant charging circuit based on magnetic core-type pulse transformer are analyzed. Experimental results of the pulse transformer are in good agreement with the theoretical calculation. When the primary capacitor is 3.17 μF and charge voltage is 1.8 kV, a voltage across the secondary capacitor of 0.88 nF with peak value of 68.5 kV, rise time (10%-90%) of 1.80 μs is obtained.     

Note: Compact high voltage pulse transformer made using a capacitor bank assembled in the shape of primary

The experimental results of an air-core pulse transformer are presented, which is very compact (<10 Kg in weight) and is primed by a capacitor bank that is fabricated in such a way that the capacitor bank with its switch takes the shape of single-turn rectangular shaped primary of the transformer. A high voltage capacitor assembly (pulse-forming-line capacitor, PFL) of 5.1 nF is connected with the secondary of transformer. The transformer output voltage is 160 kV in its second peak appearing in less than 2 μS from the beginning of the capacitor discharge. The primary capacitor bank can be charged up to a maximum of 18 kV, with the voltage delivery of 360 kV in similar capacitive loads.     

High-current pulse switching by thyristors triggered in the impact-ionization wave mode

The operation of a thyristor switch triggered in the impact-ionization wave mode was investigated. The switch contained two series-connected Т253-800-24 thyristors of the tablet design with a semiconductor- structure diameter of 56 mm. When a triggering pulse is applied to the switch at a voltage rise rate dU/dt of more than 1 kV/ns, the transition time of the thyristors to the conducting state was shorter than 1 ns. It was shown that the maximum amplitude of the no-failure current increases with an increase in dU/dt at the triggering stage. The possible mechanism of the influence of the dU/dt value on the thyristor breakdown current is discussed. In the safe operating mode at dU/dt = 6 kV/ns (3 kV/ns per single thyristor), the switch discharged a storage capacitor with a capacitance of 1 mF, which was charged to a voltage of 5 kV, through a resistive load of 18 mΩ. The following results were obtained: the discharge-current amplitude was 200 kA, the initial current rise rate was 58 kA/μs, the pulse duration (FWHM) was 25 μs, and the switching efficiency of 0.97.     

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.     

A compact high-voltage pulse generator with opening insulated-gate bipolar transistor switch and a high pulse repetition rate

A small-size high-voltage (～20 kV) microsecond pulse generator, which is based on a pulse transformer and loaded into a reactor with a pulse corona discharge, is described. Insulated-gate bipolar transistors (IGBTs) that form the switch are used in the low-voltage circuit of the generator. When the switch is open, voltage pulses with an amplitude of up to 1000 V are created across it and, hence, across the primary winding of the transformer. The pulse repetition rate of the generator is ～20000 pulses/s.     

A generator of electrical discharges in water

A semiconductor high-voltage pulse generator for the electric-discharge water purification is described. It is based on a low-voltage capacitor storage, step-up pulse transformer, and high-voltage output circuit with a recuperation section returning inefficiently used energy to the power source of the capacitor storage.     

A semiconductor opening switch-based quasi-rectangualr pulse generator operating into a low-impedance load

A generator with a semiconductor opening switch (SOS-diode) operating into a low-impedance load of 4–5 Ω is studied. The amplitude of quasi-rectangular pulses is 50 kV at a half-height duration of 100 ns. The energy is applied from an intermediate storage via a spark gap to the output generator stage. The output pulse is formed by solid-state components.     

Mega-ampere submicrosecond generator GIT-32

The GIT-32 current generator was developed for experiments with current carrying pulsed plasma. The main parts of the generator are capacitor bank, multichannel multigap spark switches, low inductive current driving lines, and central load part. The generator consists of four identical sections, connected in parallel to one load. The capacitor bank is assembled from 32 IEK-100-0.17 (0.17 microF, 40 nH, 100 kV) capacitors, connected in parallel. It stores approximately 18 kJ at 80 kV charging voltage. Each two capacitors are commuted to a load by a multigap spark switch with eight parallel channels. Switches operate in ambient air at atmospheric pressure. The GIT-32 generator was tested with 10, 15, and 20 nH inductive loads. At 10 nH load and 80 kV of charging voltage it provides 1 MA of current amplitude and 490 ns rise time with 0.8 Omega damping resistors in discharge circuit of each capacitor and 1.34 MA530 ns without resistors. The net generator inductance without a load was optimized to be as low as 12 nH, which results in extremely low self-impedance of the generator ( approximately 0.05 Omega). It ensures effective energy coupling with low impedance loads like Z pinch. The generator operates reliably without any adjustments in 40-80 kV range of charging voltage. Maximum jitter (relative to a triggering pulse) at 40 kV charging voltage is about 7 ns and lower at higher charging voltages. Operation and handling are very simple, because no oil and no purified gases are required for the generator. The GIT-32 generator has dimensions of 3200 x 3200 x 400 mm(3) and total weight of about 2500 kg, thus manifesting itself as a simple, robust, and cost effective apparatus.     

Time delay of a field-breakdown triggered vacuum switch with flat electrodes

Triggered vacuum switch (TVS) is one of the important switch apparatuses in the field of pulsed power system. The field-breakdown will bring long lifetime of TVS under rated working conditions. However, the load of trigger will be heavy, leading to the large time delay and jitter time. In this paper, a field-breakdown TVS sample with flat electrodes was fabricated and its time delay was tested. Initial plasmas play an important role in the turning-on process of TVS, so the time delay from the control signal to the switching-on of TVS is discussed in the trigger system time, the motion time and the collapse time, where the motion time and the collapse time are the needed time for the generation and development of the initial plasmas. Test results show that, under positive working mode, the trigger system time is about 34–36 μs with positive trigger pulse, while 39–41μs with negative trigger pulse, which prove that the polarities of trigger pulse have nothing to do with the trigger system time almost, and the long trigger system time is mainly owing to the limited performances of trigger pulse transformer. The motion time is about 50 ns and almost stable, due to the definite trigger gap. The collapse time is about 100–300 ns, which is decreased with the rise up of main gap voltage, exponentially. In negative working mode, both of the motion time and collapse time are about 10 μs, due to the ions of initial plasmas becoming the main moving particles in the main gap, no longer the electrons as positive working mode.     

A megavolt frequency generator pulses with an FWHM duration of 30 ns

A generator of a pulse voltage with an amplitude of up to 1 MV based on a ten-stage voltage multiplier is described. The generator contains a control panel, a unit for periodical triggering of spark gaps in the generator stages, and a rectifier outputting a voltage of ± 50 kV for charging capacitors in stages. The generator has an output discharge capacitance of 500 pF, a stored energy of 250 J, a self-inductance of <0.7 μH, a guaranteed service life of 10⁵ charging-discharging cycles, a rise time of the first voltage half-wave of 15 ns at a load of 200 pF, and a repetition rate of 1 Hz. To reduce the self-inductance of the source, insulating housings of capacitors and spark gaps are used in its layout.     

A 1-MJ capacitive energy storage

A capacitive energy storage is intended for generating high-power current pulses. The setup consists of two capacitive energy storage modules, a control console, and a cable collector for connecting a load to the setup. Each module is a capacitive energy storage with a 0.5-MJ stored energy and 18-kV voltage, which is based on eight capacitor cells with reverse switch-on dynistors as switches. The module volume is 1.3 m³. The semiconductor switches in the capacitor cells are activated by light pulses, which are transmitted from the control console through fiber-optic cables. The unit is designed for operating in the programmable discharge mode, at which the semiconductor switches in the capacitor cells are switched on nonsimultaneously but in accordance with a specified program. When the discharge of all the cells is switched on simultaneously and the load is short-circuited, the maximal amplitude of the output current pulse is 800 kA. The rise time of the discharge current pulse of the cell is 150 μs.     

Nanosecond square high voltage pulse generator for electro-optic switch

A scalable square high voltage pulse generator, which has the properties of fast rise time, fast fall time, powerful driving capability, and long lifetime, is presented in this paper by utilizing solid state circuitry. A totem-pole topology is designed to supply a powerful driving capability for the electro-optic (EO) crystal which is of capacitive load. Power MOSFETs are configured in series to sustain high voltage, and proper driving circuits are introduced for the specific MOSFETs configurations. A 3000 V pulse generator with ~49.04 ns rise time and ~10.40 ns fall time of the output waveform is presented. This kind of generator is desirable for electro-optic switch. However, it is not specific to EO switch and may have broad applications where high voltage fast switching is required.     

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.     

An PBЕ-73C vacuum spark gap with a control circuit based on an inductive energy storage

The design and operating principle of a small (50 mm in diameter and 100 mm in height) РВЕ-73C vacuum spark gap are described. It is shown that it can be efficiently switched using a control circuit with a low (∼900 V) supply voltage, which is based on an inductive energy storage and a diode opening switch that forms a high-voltage igniting pulse with a rise time of nanosecond duration. The РВЕ-73C switching process is investigated at different rise times of igniting voltage pulses and different igniting current amplitudes. The results of tests of the spark gap operating in regimes of switching current pulses with an amplitude of 12 kA and a rise time of 800 ns are presented.     

Formation of a 1.3-MV voltage pulse across a 13-Ω load with the help of the model BMΓ-160 magnetocumulative generator

An energy source designed on the basis of a BMΓ-160 magnetocumulative generator with transformer output, which enables one to form high-power (>100 GW) pulses with a current rise time of ∼1 μs across a 10-Ω load is described. Test results are provided for the generator with a load in the form of a liquid resistor connected to the source through two series gas-filled discharge switches with a trigger level of 300–350 kV each. A voltage pulse of 1.3 MV was obtained across a resistive load of 13 Ω by means of electric explosion of the conductors. Experimental pulse parameters correspond to theoretical data. Numerical simulation indicates that voltage pulses with magnitudes >1 MV and a rise time of ∼100 ns can be formed across a resistance of 13 Ω.     

Small switches of high-power microsecond pulses on the basis of high-voltage integrated pulse thyristors and reverse switch-on dynistors

A high-voltage switch on the basis of a small unit of series-connected high-voltage integrated pulse thyristors (HVIPTs), which were developed at the Ioffe Physical Technical Institute, was designed and investigated. At a power voltage of 25 kV, current pulses of microsecond duration with an amplitude of 2.8 kA and a rise time of 0.8 μs were switched. The attained current density through an HVIPT (5.6 kA/cm²) appreciably exceeds the permissible current density for conventional thyristors. It is shown that the developed HVIPT unit can be used in the triggering circuit of a high-power assembly of reverse switch-on dynistors (RSDs) at an operating voltage of 25 kV, which consists of 14 series-connected dynistors with a diameter of their structures of 24 mm. The RSD switch with a triggering circuit on the basis of HVIPTs allowed switching of rapidly rising current pulses with an amplitude of 20 kA and a duration of 150 μs. The small dimensions of the HVIPT unit (4 × 10 × 32 cm) and the RSD assembly (7 × 7 × 34 cm) determine the wide prospects for using them in high-power pulse technology.