Nanosecond-pulse gliding discharges between point-to-point electrodes in open air

Abstract

In this paper, gliding discharges with a point-to-point electrode geometry were produced by a repetitively pulsed power supply with a rise time of ∼100 ns and a full-width at half-maximum of ∼200 ns. The characteristics of such discharges were investigated by measuring their voltage-current waveforms and taking photographs of their discharge images. Experimental results showed that once the breakdown occurred, the nanosecond-pulse gliding discharges went into a stable stage at all air gaps, behaving in a mode of repetitive sparks. Under certain conditions, a non-stable stage would appear some time after the discharge went into the stable stage, in which the gliding discharges transitioned from repetitive sparks to diffuse discharges. Furthermore, several factors (gap spacing, pulse repetition frequency (PRF) and gas flow rate) influencing the discharge characteristics were investigated. It was observed that both the breakdown voltage and ignition voltage increased with the gap spacing, and a diffuse discharge was absent when the gap spacing was less than 6 mm. The breakdown voltage decreased with the increase in the PRF and its decrease ratio was larger in large gap spacing than in small gap spacing. Discharges would transit from repetitive sparks to diffuse discharges as the flow rate increased. Furthermore, a comparison of nanosecond-pulse and ac gliding discharges was conducted with respect to the power supply. The consumption and energy, the relationship between the power supply and the load, and the time interval between two pulses were three main factors which could lead to different characteristics between the nanosecond-pulse and ac gliding discharges.

Breakdown features of a high-voltage nanosecond discharge initiated with runaway electrons at subnanosecond voltage pulse rise time

“…The voltage pulse produced with the RADAN-220 pulser was applied through a short transmission line (5) to an electrode with small radius of curvature (7). The potential electrode (7) was a tube (Ø ~ 6 mm) made of 100-µm-thick stainless steel foil, and the grounded electrode (9) was a plate, which located at a distance of 13 mm from the edge of the potential one.…”

“…The main feature of such discharges is a generation of runaway electrons and X-ray in the gap, which affect, including, on the breakdown. In [1][2][3][4][5][6][7][8][9] it was shown, that these processes provide the formation of discharges in diffuse form at the excitation of gas medium by high-voltage nanosecond pulses of both polarities. It was proposed to call this type of discharge runaway electrons preionized diffuse discharge (REP DD) [3,9].…”

Translational, rotational, vibrational and electron temperatures of a gliding arc discharge

“…Substantial progress in studying gliding arc discharges has been achieved, including transient discharge processes [30,31], electrical characteristics [32,33], hypergravity effects [34,35] and species distributions [36][37][38], as well as the rotational and vibrational temperatures of gliding arc discharges [25][26][27][28]. However, the translational temperature of the gliding arc discharge has not been directly measured yet up to now.…”

Measurements of 3D slip velocities and plasma column lengths of a gliding arc discharge

“…5,6 Such gliding arc discharges have been widely applied to pollution control, 7-11 surface treatment, 1,12 sterilization, 13 and combustion enhancement. 14 Extensive studies have been performed on the dynamics, [15][16][17][18] physical characteristics, [19][20][21][22][23][24][25][26][27][28] and chemical mechanisms [29][30][31] involved in gliding arc discharges. Phenomenological models 21,[32][33][34] were developed to explain the discharge behavior based on accurate measurements of several important parameters, including the slip velocityṼ S (it stands for the relative velocity between the plasma columnṼ C and the gas flowṼ F , and its magnitude is jṼ S j ¼ jṼ C ÀṼ F j), and the length of the plasma column.…”