E. A. Shershunova

Series Circuit Resistance as Factor of DBD Mode in Air at Different Barrier Materials

This paper deals with the realization of a diffuse dielectric barrier discharge in air at atmospheric pressure using a high-voltage pulse generator operating in a single-pulse mode and at frequencies of tens of hertz. This paper is focused on the effects of the series resistor and dielectric materials. It is shown that the parameters of the external circuit strongly influence the discharge mode.

On the possibility of generating volume dielectric barrier discharge in air at atmospheric pressure

A homogeneous volume dielectric barrier discharge (DBD) in air at atmospheric pressure and natural humidity has been obtained. Conditions ensuring generation of a homogeneous DBD are described. It is shown that a determining influence on the homogeneity of DBD is produced by the rate of electric field strength growth in the discharge gap.

High-voltage solid-state switches for microsecond pulse power

A method that controls solid-state insulated gate bipolar transistor (IGBT) switches, allowing one to increase their ON-state duration time from fractions of microseconds up to milliseconds, is proposed. It is shown that the ON-state duration of the switches is limited only by their overheating. The modular design of the high-voltage solid-state switch with a 16-kV operating voltage and 60-A pulse current is experimentally implemented.

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.

Solid-State System for Copper Vapor Laser Excitation

Abstract The present paper describes an all-solid-state high voltage nanosecond pulse generator for pumping a copper vapor laser. The main feature of this device is using a high voltage switch composed of a stack of insulated gate bipolar transistors (IGBT), what makes it compacter and more cost effective than traditional systems based on thyratrons and vacuum tubes. A fast transformer circuit provides highly synchronous on/off control of the IGBT stack. Two-stage magnetic pulse compressor is used to enhance the system efficiency. The developed laser pumping system generates current pulses with amplitude of 230 A and rise time of 30 ns at pulse repetition rate of 15 kHz. Average laser output power of 13 W was obtained under these pumping conditions.

On the homogeneity of a diffuse barrier discharge in atmospheric air between flat cylindrical electrodes

The degree of homogeneity of a diffuse dielectric barrier discharge in millimeter air gaps under atmospheric pressure has been analyzed. This analysis is based on the glow-brightness distribution in the discharge gap cross section with allowance for a cylindrical electrode shape. It is shown that the degree of discharge homogeneity depends on both the repetition frequency of voltage pulses applied to the discharge gap and the barrier material.

High voltage IGBT switch with capability of pulse width control

High voltage switch unit on a base of isolated gate bipolar transistors (IGBT) with operating voltage of 4.5 kV and capability of pulse width control is developed and investigated. The start-stop circuit of IGBT gates control lets the switch to be open for near unlimited periods of time up to be continually open at constant nanosecond delay time.

Two methods of pumping for eximer laser pulse-stretching

Stretching of laser pulses allows to improve eximer laser output characteristics and to prolong a laser lifetime. Two methods of laser pumping are proposed in this paper for stretching of laser pulses. Using a special electric circuit in a pumping generator scheme allowed to double a pulse duration for a small ArF-laser. For the first time a pumping mode with periodically damping voltage across a discharge gap was successfully realized for increasing of KrF-laser pulse duration.

A Compact Source of Flash-Corona Discharge for Biomedical Applications

A compact source of low-temperature plasma for biological and medical applications is proposed, which operates at kilohertz frequencies in the regime of flash-corona discharge with an energy of 0.1 mJ/pulse. The plasma source was tested in application to plasma pretreatment of green salad seeds. Plasma-treated seeds exhibited increased (by about 25%) germination speed as compared to that in the untreated control.

Radial Distribution of the Nanosecond Dielectric Barrier Discharge Current in Atmospheric-Pressure Air

Experimental results on the radial distribution of the nanosecond dielectric barrier discharge (DBD) current in flat millimeter air gaps under atmospheric pressure and natural humidity of 40–60% at a voltage rise rate at the electrodes of 250 V/ns are presented. The time delay of the appearance of discharge currents was observed to increase from the center to the periphery of the air gap at discharge gap heights above 3 mm, which correlated with the appearance of constricted channels against the background of the volume DBD plasma. Based on the criterion of the avalanche-streamer transition, it is found out that the development of a nanosecond DBD in air gaps of 1–3 mm occurs by the streamer mechanism.