Dynamics of multichannel and quasi-homogeneous sliding discharge formation in rare gases

Abstract

Results of experiments with Ne, Ar and Xe as well as computer simulations are presented, aimed at testing an earlier proposed model of temporal dynamics of multichannel structure development in a pulsed high-current sliding gas discharge. The obtained and discussed experimental data include the values of an averaged channel radius, the pulsed near-surface breakdown voltage, the saturated spark resistance, the spatial structure of spark channels registered photographically under different discharge voltages and the oscilloscope traces of the discharge gap voltage. The experiments were performed at two values of gas pressure (30 and 100 kPa) with a setup in two modifications which differed from each other by an impedance (27 times) and a stored electric energy (250 times) of a pulsed power supply source. A comparison of the experimental channel structure and the discharge voltage time dependence with those calculated using the discussed model showed good agreement, and this approves an application of the model to quantitative estimations of the sliding discharge parameters. The relation revealed between the channel radii and the square root of mobility of electrons is explained by a drift of electrons in a transverse electric field. Attention is also paid to the problem of stability of a multichannel mode of the sliding discharge. Both experimental data and computer modelling demonstrate that the most stable mode of the discharge is a quasi-homogeneous one, in which the spark channels fill the interelectrode gap entirely. But a certain instability of plasma brightness seems to be an intrinsic feature of the multispark sliding discharge even in its quasi-homogeneous mode, which results from non-simultaneous initiation of the spark channels.

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