The theory of positive glow corona

Abstract

A theory for the current and light pulses of positive glow corona from a point in air is presented; this phenomenon was first observed as an apparently continuous glow by Michael Faraday. Results are obtained, in concentric sphere geometry, for air at atmospheric pressure, by solving the continuity equations for electrons, positive ions, negative ions and metastable oxygen molecules, coupled with Poisson's equation. A series of `saw-toothed' current pulses of period about is predicted with a DC current level. Accompanying the current peaks are discrete pulses of light 30 ns wide. Successive `shells' of positive ions, from successive current pulses, carry 96% of the mean current. The mean current - voltage relationship has the classic square-law form. The seed electrons required for successive pulses are detached from negative ions by metastable oxygen molecules. Photo-ionization is crucial for the discharge at the anode and for the formation of negative ions throughout the gap. The pulse frequency varies with applied voltage and is found to be approximately proportional to the positive-ion mobility. The surface electric field at the central electrode remains close to Peek's onset field. The origin of onset streamers is explained and sub-microsecond voltage pulses are found to produce streamers. The results for concentric-cylinder electrodes are described briefly.

Physics of self-sustained oscillations in the positive glow corona

“…The minor discrepancies in the electrode current waveforms between the result of this work and the experimental measurements by others can be attributed to the differences in the setup of the apparatus. [2][3][4][5][6] Illustrated in Fig. 16(a) is the equivalent circuit diagram representation for a typical apparatus in the glow corona experiments.…”

“…To this date, the basic underlying mechanism behind such self-sustained current oscillations remains unclear. [2][3][4][5][6] Morrow did a theoretical work in an attempt to explain the underlying physics behind the self-sustained current oscillations in the positive glow corona. 4 Qualitatively, his predictions are consistent with the various experimental observations by others.…”

“…[2][3][4][5][6] Morrow did a theoretical work in an attempt to explain the underlying physics behind the self-sustained current oscillations in the positive glow corona. 4 Qualitatively, his predictions are consistent with the various experimental observations by others. Despite the fact that plasmas are ionized gases, 12,13 which may contain particles of all charged species (positive, negative, or neutral) of various sizes (atoms or nanoparticles), Morrow showed that the selfsustained oscillations in the electrode current are predominantly due to the mobility of the positive ions in the gas.…”

“…This result is compared with waveforms of experimental discharge current measurement at the electrode for a positive corona in nitrogen at 35 Torr by Akishev et al 5 Similarly, the result is also compared with the prediction by Morrow. 4 Remarkably, the profile of Eq. (37), which is shown in Fig.…”

“…[2][3][4][5][6] The selfsustained pulsing in the positive glow corona (also referred to as direct current (DC) glow discharge) can be qualitatively explained from the aforementioned, oscillating, chargedparticle dynamics. In this paper, I shall show that the selfsustained pulsing in the positive glow corona involves the kind of charged-particle oscillation mechanism discussed in Figs.…”