D. A. Korotkov

Dynistors with nanosecond response times

The results of studies of deep-level dynistors (DLDs) in modes of switching high-power nanosecond current pulses at a current rise rate of up to 200 A/ns unique for semiconductor switches are presented. The dependences of the switching energy loss in DLDs on the amplitude of the control current and the shape of triggering voltage pulses are shown. The electrophysical processes developing at the edge surface of a DLD subjected to the application of high-voltage triggering pulses are analyzed.

Installation for air cleaning from organic impurities by plasma formed by barrier discharge of nanosecond duration

A prototype installation for air cleaning by plasma, which consists of a barrier-type discharge reactor and a high-voltage nanosecond-pulse supply generator, which is based on drift step recovery diodes, is considered. A stable corona-type barrier discharge was obtained at a 3-kHz supply-pulse repetition frequency. The discharge remained nonlocalized even at a small gas-discharge gap (∼6 mm) due to a short (∼25 ns) pulse duration, which allows a quite uniform effect on the air flow. The high rise rate (∼6 kV/ns) of the applied supply voltage pulses determines the high voltage amplitude (∼25 kV) at the reactor at the breakdown moment and allows maintenance of high electric-field intensity and a high intensity of plasma chemical processes. Thus, an electrical power lower than 8 W is required at the reactor input to produce 1 g of ozone per hour. The concentration of methylmercaptan in air during waste-water smell deodorizing at State Unitary Enterprise “Vodokanal of St. Petersburg” was reduced down to an allowable level of 0.5 mg/m3 at the electrical power consumption no higher than 0.25 W per cubic meter of air.

Semiconductor switches of laser pumping pulses of nanosecond duration

Switches of megawatt nanosecond pulses based on high-voltage (12 kV) assemblies of drift step-recovery diodes (DSRDs) and deep-level dynistors (DLDs) are described. Circuit diagrams allowing their use in laser technology are considered. Results of testing of the diode and dynistor switches in power supply circuits of nitrogen lasers at a frequency of 100 Hz are presented. Their high efficiency in shaping of pumping current pulses with a rise time of 10 ns and amplitudes of 500 A (a DSRD switch) and 900 A (a DLD switch) is shown.

High-power switches based on reversely switched-on dynistors for high-voltage pulse technologies

The results of comparative investigations of commercially produced reversely switched-on dynistors (RSDs) with an operating voltage of 2 kV and 76-mm-diameter structures are presented. The studies were performed in the mode of switching current pulses with an amplitude of 200 kA and a duration of 300 μs. The electric scheme of the power circuit of the generator of high-power high-voltage pulses with a switch on the basis of an assembly of RSDs is considered. RSD switches with an operating current of 250 kA and operating voltages of 12 and 24 kV are described. Some results of using RSD switches in high-voltage pulse technologies are presented.

High-voltage diode-dynistor switches of high-power alternating current pulses

Electric circuits of high-power switches based on assemblies of diodes that are connected in series to reverse switch-on dynistors (RSDs) are considered. They allow RSDs to be efficiently used in the modes of switching high-power weakly decaying current pulses, which were previously impossible because of high energy losses in dynistors during the reverse-current flow. The results of a comparative study of high-voltage (24 kV) diode-dynistor switches under the conditions of switching current pulses with an amplitude of 50 kA and a damping decrement of 1.3 are presented. The possibility of increasing the switched power is shown.

Studying dynistor switches with nanosecond switching times

The results of studying the process of switching deep-level dynistors (DLDs) with 16- and 24-mm-diameter structures in the modes of switching micro- and nanosecond pulses with amplitudes of several kiloamperes are presented. It is shown that the dynistor switching process is highly uniform. The results of DLD tests at a high repetition rate of switched current pulses are presented. The principle of constructing high-power DLD switches with independent triggering of dynistors, which is based on the use of a single-turn saturable-core choke in the power circuit and a saturable-core isolating transformer in the DLD triggering circuits, is described. A DLD switch with an operating voltage of 8 kV is considered, which can switch current pulses at a frequency of 2 kHz with an amplitude of 1.5 kA and a duration of 200 ns.

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 modular drift step-recovery diode generator for nanosecond pulse technologies

A generator of nanosecond pulses with an energy of ~50 mJ, which provides switching of voltage pulses with an amplitude of ~17 kV and a rise time of ~4 ns at a repetition frequency of 8 kHz to a 75-Ω resistive load, is described. The load is matched to the generator output cable. The generator is based on an opening switch in the form of a unit of drift step-recovery diodes (DSRDs). The conditions for the efficient operation of DSRDs are provided by six self-contained modules each of which contains an IGBT transistor and a step-up saturable-core transformer. The results of an experimental study of the generator are presented. They indicate a high efficiency of the developed modular circuit, which makes it possible to increase the switched energy virtually in proportion to the number of used modules, and the possibility of reducing the switching energy loss in the DSRD unit in proportion to the number of diode assemblies connected in parallel. It is shown that the generator can be used for producing ozone and high-purity silicon tetrafluoride and also in an apparatus for purifying air of organic pollutants.

Investigation of Silicon Diodes in the Mode of Switching by an Impact-Ionization Wave

The results of investigations of silicon diodes in the mode of switching by nanosecond pulses, which initiate an impact-ionization wave, are presented. It is shown that the switching process is significantly influenced by dislocations that are formed in the surface layers of diode structures during their manufacture.

Switches of High-power Current Pulses with a Submicrosecond Rise Time on the Basis of Series-connected IGBT Transistors

The results of comparative investigations of assemblies of series-connected IGBT transistors (IRGPS60B120KD) with control circuits that are based on pulse transformers and ADuM21N microcircuits, which have a high insulation strength, are presented. The conditions for efficient switching of high-power current pulses with a submicrosecond rise time are determined. A small switch with an operating voltage of 12 kV that consists of two parallel-connected transistor assemblies is described. It provides switching of microsecond current pulses with an amplitude of 500 A and a rise time of 200 ns at a frequency of 100 Hz under natural cooling. The possibility of scaling the results is shown.