V. Yu. Khomich

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.

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.

Electrohydrodynamic effect resulting from high-frequency barrier discharge in gas

The formation of an electrohydrodynamic flow in atmospheric air by using a high-frequency barrier discharge distributed over the dielectric surface is investigated. The influence of variations in parameters of a fully solid-state pulse generator (with a peak voltage of 0–12 kV, a tunable repetition rate of 10–25 kHz, and a pulse duration of 7 μs) on the current of plasma ion emitter and velocity characteristics of airflow is considered.

Formation of nanostructures during laser-induced melting of solid surfaces

In recent years, nanostructures in solids have begun to receive more attention from researchers as important objects having very promising applications in various fields of science and technology. Ordered and disordered ensembles of nanoparticles represent new artificial materials with a broad range of applications due to their unique properties. The nanostructured surfaces improve the electrical, thermal, and electron-emission properties of materials and lead to better compatibility of tissues with implants used in orthopedics and dentistry. They also find application in selective nanocatalysis, microelectronics, nanophotonics, spectroscopy, and high-power optics; ensure superhigh data recording density; and are used in developing light-emitting silicon-base devices. This implies a need for developing the physical foundations of new effective methods for the formation of two- and three-dimensional structures with characteristic sizes less than one micrometer both at the surface and in the bulk of solids and for studying the mechanisms of nanostructure formation, which can be of various natures. In this study, the possibility of forming nanostructures at solid surfaces by laser pulses leading to the melting of the material surface is evaluated. The action of a laser pulse with a certain energy density and duration on a solid surface can lead to the melting of the surface layer. Let us consider the process of its solidification due to subsequent heat removal in the depth of the solid phase. In this case, the liquid turns out to be in the supercooled state and a considerable temperature difference across the liquid‐solid interface is established. Depending on the degree of supercooling, the subsequent nucleation of the crystal phase can have either a fluctuational [1] or a spontaneous [2] character (Fig. 1). The variation of the thermodynamic potential during the formation of a new phase center (nucleus) consisting of n atoms can be described as follows:

Study of the homogeneity of the current distribution in a dielectric barrier discharge in air by means of a segmented electrode

The current distribution in a dielectric barrier discharge in atmospheric-pressure air at a natural humidity of 40–60% was studied experimentally with a time resolution of 200 ps. The experimental results are interpreted by means of numerically simulating the discharge electric circuit. The obtained results indicate that the discharge operating in the volumetric mode develops simultaneously over the entire transverse cross section of the discharge gap.

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.