Prebreakdown stage of a surface discharge fired by a pulse in the air at atmospheric pressure

Abstract

533.95Results of investigation of a high-current plane pulsed surface discharge with separated torches fired in the air at atmospheric pressure are presented. The dynamics of ignition and development of the discharge in the prebreakdown stage has been considered. The main parameters of the plasma in the prebreakdown stage (the stage of intense prebreakdown glow) have been determined by spectroscopic methods and the influence of the dielectric material of a substrate on the plasma parameters has been analyzed. It has been established that the duration of an intense prebreakdown glow depends on the experimental conditions. A physical pattern of formation of an intense prebreakdown glow is proposed.The operation of many electric-discharge systems is based on a high-current pulsed discharge on a dielectric surface. A plane pulsed surface discharge is widely used in intense radiation sources for photography and spectroscopy [1][2][3][4][5] and in various lasers [6,7]. A cylindrical pulsed surface discharge finds wide application in generators of pulsed erosion plasma jets (pulsed-erosion-plasma accelerators, plasmatrons, diaphragm electric-discharge shock tubes, etc.). Considerable recent attention has been focused on the use of a plane pulsed surface discharge for investigating the bactericidal action of a spark discharge on a water surface (in a similar way to a discharge in a water volume) [8] and the plasma-chemical destruction of freons (a creeping surface discharge [9]). However, as judged from the available literature, a high-current pulsed surface discharge has not been adequately explored. Therefore, we attempted to make up for this deficiency.In the present work, prominence was given to the study of the formation of the surface plasma at the initial stage of a plane pulsed surface discharge and the influence of this stage on the further development of the discharge. We also investigated the dependence of the plasma formation on the material of the electrodes and the substrate and the ambient pressure. For more complete understanding of the physical processes occurring in a plane pulsed surface discharge with separated torches, the gasdynamic structure of the electrode plasma torches and its influence on the dynamics of the discharge and the plasma formation were considered. The experimental investigation of surface plasma formations was supplemented with the theoretical study of the discharge dynamics, which made the analysis of the results obtained easier.Apparatus, Experimental Conditions, and Investigation Methods. A pulsed surface discharge was experimentally investigated using a discharge device of plane configuration with a parallel placement of electrodes (Fig. 1). This device allows one to simultaneously investigate the near-electrode and near-wall regions of the discharge under the conditions where the electrode plasma torches are separated and free to flow, which eliminates the contribution of the torch component to the electrode erosion and the collision of supersonic electrode torches [10,11].A d...

Plasmadynamic Structure of Electrode Torches and its Influence on the Dynamics of Development of Pulsed Surface Discharge

“…The electrophysical characteristics and substantiation of selection of the material of a plasma-generating dielectric have been presented in [5].…”

“…All the investigations were carried out in the unit-pulse regime and the initial conditions were reproduced after each discharge. The horizontal position of the substrate surface was controlled with a light beam.The electrophysical characteristics and substantiation of selection of the material of a plasma-generating dielectric have been presented in [5].The dynamics of development of the discharge was studied with high-speed UPhR cameras and a driven photorecorder (photochronograph) (DPhR). The UPhR camera was used as a photorecorder giving a free-running continuous scan of the process under study and as a time lens giving a sequence of photographs of the process studied.…”

Electrodynamic model of combustion chamber using subcritical streamer discharge to ignite fuel mixture

“…Properties of freely localized microwave discharges in a focused beam of quasi-optical radiation have been studied quite well [7,8]. Various approaches to modeling microwave radiation propagation in waveguides with different crosssectional shapes have also been developed [9,10].…”

Diagnostics of Surface-Plasma Formations in a Pulsed Surface Discharge

“…All investigations were carried out in the regime of single pulses and, after each discharge, the initial conditions were reproduced. The horizontal position of the substrate was controlled using a light ray.The electric characteristics of the device were described in [8].Substrates of fluoroplastic, the crystalline salt NaCl, and textolite were used in the investigations. The substrates were made in the form of a parallelepiped 4 × 2 × 1 cm in size.…”