Detailed Investigation of the Electric Discharge Plasma between Copper Electrodes Immersed into Water

Abstract

Abstract:A phenomenological picture of pulsed electrical discharge in water is produced by combining electrical, spectroscopic, and imaging methods. The discharge is generated by applying 350 µs long 100 to 220 V pulses (values of current from 400 to 1000 A, respectively) between the point-to-point copper electrodes submerged into the non-purified tap water. Plasma channel and gas bubble occur between the tips of the electrodes, which are initially in contact with each other. The study includes detailed experimental investigation of plasma parameters of such discharge using the correlation between time-resolved high-speed imaging, electrical characteristics, and optical emission spectroscopic data. Radial distributions of the electron density of plasma is estimated from the analysis of profiles and widths of registered H α and H β hydrogen lines, and Cu I 515.3 nm line, exposed to the Stark mechanism of spectral lines' broadening. Estimations of the electrodes' erosion rate and bubbles' size depending on the electrical input parameters of the circuit are presented. Experimental results of this work may be valuable for the advancement of modeling and the theoretical understanding of the pulse electric discharges in water.

Hydrogen Balmer spectral lines in spectroscopy of underwater electric spark discharge plasma

“…As for Hβ spectral line, electron density value, obtained from the width of this line is by one order of magnitude lower in comparison of value, obtained from the width of Cu I 570.0 nm spectral line. That is the similar results, obtained in previous work (Venger et al, 2017) and, obviously, must be as a subject of future investigation.…”

“…Specifically, copper and hydrogen spectral lines are widely used for it. Cu I spectral lines are well-studied and widely used (usually Cu I 515.3 nm, broadened by quadratic Stark effect Konjević & Konjević 1986) for electron density measurements (Babich et al, 2014;Fesenko et al, 2014;Venger et al, 2017) as well as Hydrogen lines (Venger et al, 2017;Nikiforov et al, 2015;Wang et al, 2019;Jovičević et al, 2004).…”

“…In previous work the Hα shape was studied in underwater spark discharge (Tmenova et al, 2017) and in underwater arc discharge with Hβ spectral line (Venger et al, 2017). Electron density, obtained in Venger et al (2017) from the width of Cu I 515.3 nm and Hα spectral lines were of the same order of magnitude for all the studied power modes, values of N e , obtained from the width of Hβ line were by two orders of magnitude lower for the cases of arc current of 660 and 800 A, and by one order of magnitude lower for the case of 1000 A. It aroused interest to study the behavior of Hβ spectral line profile in underwater spark discharge.…”

Interpretation of Stark broadening measurements on a spatially integrated plasma spectral line

“…For the experimental characterisation of an electric arc, emission spectroscopy is the diagnostic method of choice for the measurement of the plasma temperature or species densities. Among the different spectroscopic diagnostic methods, those based on the measurement of the Stark broadening of a spectral line are widely used [1][2][3][4][5][6].…”

“…We are interested in the theoretical determination of the electron density by measurement of the broadening of a spectral line. We are interested in the hydrogen spectral line Hα for which we consider the Stark effect as the dominant source of broadening in the presence of a high electron density [2].…”