Modelling of plasma chemical processes in pulsed corona discharges

Abstract

By a two-dimensional numerical simulation of positive streamers in atmospheric air in sphere - plane gaps, the G-values (numbers of radicals per 100 eV of input energy) for the production of oxygen and nitrogen atoms are obtained. Calculated G-values weakly depend on the applied voltage and parameters of the gap and are about 3 - 4 and 0.3 - 0.4 respectively. In the frame of the qualitative theory of streamer propagation in nonuniform electric fields, approximate formulae for G-values in streamer corona discharges are derived. The G-values are determined by the magnitudes of the reaction rate coefficients at electron energies corresponding to the maximum of the electric field in the streamer head. The formulae obtained describe well the relations between the G-values for different plasma chemical reactions and can be used for estimations of the absolute G-values with an accuracy up to a factor of two.

Positive streamers in air of varying density: experiments on the scaling of the excitation density

“…Is it possible that the production of excited nitrogen molecules is lower in thicker streamers? According to Naidis [23] and Li et al [34] the densities depend on the electric field, with higher fields leading to higher production of excited molecules (equation (1)). However, the densities predicted by this model in the range of fields relevant to streamer heads [8] are not very sensitive to the electric field, changing by a factor 4 at most, as was shown in Figure 1.…”

“…The production of various excited species and the increase of the electron density due to the passage of a streamer were simulated in several papers [3,[23][24][25][26][27][28][29][30][31][32][33], to name but a few, most of which agree that the electron density on the axis of the streamer is on the order of 10 13 − 10 14 cm − 3 . In general, the density of the excited species on the streamers axis will depend both on the neutral gas density and on the maximal electric field at the streamer tip.…”

“…In general, the density of the excited species on the streamers axis will depend both on the neutral gas density and on the maximal electric field at the streamer tip. Naidis [23] and later Li et al [34] proposed an approximation for the production of species, expressed as: Figure 1. Densities of electrons, n e , and excited molecules produced by the passage of a streamer in artificial air (N 2 :O 2 -80:20).…”

Mechanism of dielectric‐barrier discharge initiated wet‐strength development

“…[3][4][5][6][7] The use of dielectric-barrier discharge as a surface treatment for synthetic and natural polymers has gained increasing interest due to its practical benefits and applicability. 8 The cold plasma generated from a dielectric-barrier discharge contains numerous highly reactive species including electrons, 8 hydroxyl radicals, 9 positive and negative oxidized ions, 10 reactive molecules 11 such as ozone, 8 and other excited species. Surface treatment with atmospheric plasma has long been associated with the increased surface energy and wettability of polymeric and lignocellulosic materials, [12][13][14] which has been attributed to the oxidative nature of the surface treatment.…”

Electro-hydrodynamics and kinetic modelling of polluted air flow activated by multi-tip-to-plane corona discharge

“…[12][13][14][15][16][17][18][19][20][21][22][23] In the present paper, we develop a bi-dimensional simulation of an ACDR composed of ten aligned pins and crossed by a polluted dry air flow. We follow in details the spatiotemporal transformation of the NO pollutant until 10 ms by coupling 100 successive discharge/post-discharge phases with a repetition rate of 10 kHz.…”