I.A. Shemyakin

Plasma-Assisted Combustion System Based on Nonsteady-State Gas-Discharge Plasma Torch

This paper describes the experiments with the plasma-assisted combustion system as applied to gaseous hydrocarbons. The system is based on a nonsteady-state gas-discharge plasmatron with a low average current. One of the subjects of the investigations is to elucidate a correlation between the discharge burning regimes in the plasmatron and the properties of the torch flame in the combustion chamber. Depending on the gas-discharge regimes and plasmatron design, the conditions of complete hydrocarbon combustion and partial oxidation have been demonstrated. Aside from that, the data on testing a special power supply intentionally developed for nonsteady discharge powering are presented.

High-Current Stages in a Low-Pressure Glow Discharge With Hollow Cathode

This paper presents an interpretation of the dense and superdense glow discharge stages in pseudospark switch geometry. The discharge is treated as a self-organizing system that is able to rearrange itself to provide the current requested by external electric circuit. The principal discharge regions in the glow stages are the hollow-cathode plasma, the positive column plasma, and the double electric layer that separates these plasma regions. A model that allows some quantitative estimates when applied to the hollow-cathode plasma is developed, in which a generalized secondary emission coefficient that considers an external emission current is introduced. The abrupt transition from dense glow stage to superdense glow stage occurs because of microexplosions at the cathode surface and appearing the metal vapor plasma. In terms of the model, this means an abrupt increase in the secondary emission coefficient. The comparison with the experiment is made for discharges in hydrogen and xenon at a current up to several kiloamperes and at a current rise time from several microseconds to hundreds of nanoseconds. The physical reasons for the current quenching effect that manifests itself at a decreased gas pressure are also discussed.

Investigation of the effect of blocking potential on the static breakdown voltage and discharge initiation in pseudospark switches

Measurements on the currents in the pre-breakdown phase and the static breakdown voltage for the pseudospark switch with a blocking electrode and a trigger unit based on an auxiliary glow discharge are presented. The use of the blocking electrode offers the possibility to extend the range of operating pressures for the switch with conservation of a high level of static breakdown voltage and a low delay time. It is shown that the effect of the blocking electrode on the static breakdown voltage is due to suppression of the hollow cathode effect in the main gap of the switch. >

Low-voltage triggering for a pseudospark switch with an auxiliary glow discharge

Different electric circuits for triggering the switch with a trigger unit based on an auxiliary glow discharge are discussed. Most attention is concentrated on the recent experimental results on low voltage triggering of the switch and on the mechanisms for the main discharge initiation under the action of the trigger pulse. Due to modifications in the trigger electric circuit, the switch is triggered starting from a voltage of 50 V at a current level in the trigger circuit of 10 mA. With a voltage of 200-250 V and a trigger current of about 0.25 A, the delay time to triggering does not exceed 200 ns.

Temporal structure of the fast electron beam generated in the pseudospark discharge with external triggering

This paper deals with the investigation of the fast electron beams that form in the high-current pseudospark discharge at different stages of its development. Three short-duration peak of the beam current at the discharge axis have been revealed. The physical reasons for the appearance of these peaks of the beam are discussed. The main idea of the proposed physical mechanism is that the electrons are accelerated in a double electric layer, which forms between the hollow cathode plasma and the near-anode plasma.

EUV radiation from plasma of a pseudospark discharge in its different stages

The paper describes the main features of the pulsed low-pressure gas discharge in oxygen and xenon, which burns in typical conditions of EUV source operation. It is shown that in a mode of the superdense glow discharge the electron temperature in the discharge plasma is high enough to provide for generation of EUV radiation without magnetic compression of the plasma column.

Mechanism of the current quenching phenomenon in pseudospark discharge

Experimental data on the current quenching phenomenon in the pseudospark discharge in typical conditions of EUV source operation (extremely short pulse duration and high current) are presented. The mechanism of the phenomenon is proposed.

Experimental setup for investigation of the pseudospark discharge as applied to generation of EUV radiation

The paper describes the main features of the experimental installation for investigation of a high current pulsed gas discharge, which burns in typical conditions of EUV source operation.

Parallel operation of sealed-off pseudospark switches onto common load

Considerable scientific activity has been recently generated in the field of experiments on implosion of liners, plasma focus, plasma-erosion opening switches and the like. In the simplest case, experimental installation comprises a low-inductance capacitor bank charged up to a voltage, a switching device, a transmitting line and a load. Typical current for the middle-rate installations amounts to several hundreds of kiloamperes, at voltage Vo of several tens of kilovolts, and current pulse duration from 1 to 2 /spl mu/s. Most of the above installations operate in a single-pulse mode. However, some technological applications require the facilities in a pulse repetition mode with a pulse repetition rate of 1 Hz and more. In this connection, the problem of switching device for such facilities emerges. The high-pressure spark gaps are of limited utility for this problem since they fail to operate in the pulse repetition mode and have a low lifetime. Currently, a new type of low-pressure switching device with a cold cathode, a so called pseudospark switch, is under intensive investigation. This switch offers a possibility to commutate current of about 100 kA for the devices in ceramic-metal sealed-off design. This report presents some data on parallel operation of the sealed-off switches onto a common low resistance load. Virtually, the experimental conditions are chosen to model the switch operating modes for the above described applications.

Methods of triggering for the cold cathode thyratrons with auxiliary glow discharge in trigger system

The paper describes the schematic design and principle of operation for the ceramic-metal sealed-off pseudospark switches with the auxiliary glow discharge in the trigger unit. The switches are produced commercially by the Pulsed Technology Ltd., Ryazan, Russia [http://www.pulsetech.ru/index.htm] and are known as the switches of TPI-series whose anode voltage ranges from several to 50 k V. Proceeding from the switch design and the methods of triggering, the TPI switches can be referred to as the cold cathode thyratrons. Triggering methods for the electric circuits corresponding to grounded grid thyratron and to classical thyratron with cold cathode are considered.