Specific features of a single-pulse sliding discharge in neon near the threshold for spark breakdown
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TEMPERATURE PLASMA
Specific Features of a Single-Pulse Sliding Discharge in Neon Near the Threshold for Spark Breakdown K. K. Trusov Lebedev Physical Institute, Russian Academy of Sciences, Moscow, 119991 Russia e-mail: [email protected] Received October 17, 2016; in final form, December 24, 2016
Abstract—Experimental data on the spatial structure of a single-pulse sliding discharge in neon at voltages below, equal to, and above the threshold for spark breakdown are discussed. The experiments were carried at gas pressures of 30 and 100 kPa and different polarities of the discharge voltage. Photographs of the plasma structure in two discharge chambers with different dimensions of the discharge zone and different thicknesses of an alumina dielectric plate on the surface of which the discharge develops are inspected. Common features of the prebreakdown discharge and its specific features depending on the voltage polarity and gas pressure are analyzed. It is shown that, at voltages below the threshold for spark breakdown, a low-current glow discharge with cathode and anode spots develops in the electrode gap. Above the breakdown threshold, regardless of the voltage polarity, spark channels directed from the cathode to the anode develop against the background of a low-current discharge.
DOI: 10.1134/S1063780X17080104
1. INTRODUCTION The distribution of the plasma of a completed pulsed gas discharge along a dielectric surface in the regime of surface spark breakdown depends substantially on the nonuniformity of gas ionization in the prebreakdown plasma. Hereinafter, the term “prebreakdown plasma” refers to the stage in which spark breakdown has not yet occurred. It is commonly believed that prebreakdown plasma is formed by an incompleted capacitive discharge during the propagation of an ionization wave in the discharge gap [1]. The spatial structure of the prebreakdown plasma varies from uniform to streamer-like. The role played by the ionization wave in gas breakdown (both in free space and over a dielectric surface) have been studied for many years both theoretically and experimentally (see, e.g., [1–15] and references therein). The results of recent experiments with a submicrosecond sliding discharge in Ne, Ar, and Xe [16] have shown that, at the threshold for surface spark breakdown, the spatial distribution of the electron density in the prebreakdown plasma depends on the voltage polarity, gas pressure, and parameters of the discharge chamber. In Ar and Xe, the prebreakdown plasma usually has the form of streamers propagating along the dielectric surface, which transform into a spark upon breakdown, whereas the structure of the prebreakdown plasma in Ne varies from uniform to streamer-like.
The present work is a continuation of [16]. The experiments were carried out at the same experimental setup. Here, we discuss the spatial structure of a single-pulse sliding discharge in neon at voltages below and above the threshold voltage Ubreak for spark breakdown. Experiments similar to [16] were conducted with two di
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