Numerical simulation on electric field intensity and reaction pathway in the He–O2 atmospheric pressure plasma jet

Abstract

In this work, a two-dimensional fluid model of the needle-plane discharge plasma has been built to numerically investigate the spatio-temporal evolution characteristics of the electric field intensity and electric potential as well as generating and consuming reaction pathways of various oxygen species in a He–O2 atmospheric pressure plasma jet. Simulation results have indicated that the region of high electric field intensity moves in the direction of the plane electrode with the formation and propagation of an ionization wave. The region of low electric field intensity exists between the needle electrode and the head of the ionization wave, and its area increases continuously. The obvious voltage drop and local electric field enhancement occur between the head of the ionization wave and the plane electrode. Electron attachment reactions e + O2 → O + O− and e + 2O2 → O2− + O2 produce negative ions O− and O2−. More than 80% of the positive ions O2+ and H2O+ come from Penning ionizations between He* and molecules O2 and H2O. e + O2 → e + O + O(1D) is the main pathway to generate O and O(1D). O(1D) + H2O → 2OH and O + H + H2O → OH + H2O produce 69.3% and 39.2% of OH, respectively. 2O2 + O → O3 + O2 is the key generating reaction of O3.

Effect of the flow rate of the shielding gas on the species fluxes in the coaxial double-tube helium atmospheric pressure plasma jet

“…According to the previous study [24], a strong radial component of the electric field exists near the surface of the discharge channel, whereas the electric field inside the discharge channel is more uniform. Figure 11(a From equation ( 6), the electric field E and the number density of species n j are directly related to the species fluxes Γ j .…”

“…Furthermore, the main discharge channel and the discharge channel are distinguished and discussed to elucidate the impact of SG on the effluent chemistry. In this work, the contour line of 98% helium mole fraction (c He = 98%) [23] is regarded as the surface of the main discharge channel, while the border of the discharge channel is distinguished by the electric field [24]. In this case, the variations in species fluxes on the surfaces of the discharge channel and the main discharge channel are considered and discussed.…”

Physics of plasma jets and interaction with surfaces: review on modelling and experiments

“…In this case, the highest values of the ionization source term in the discharge front are off-axis and the discharge has a ring shape, which is a result of the ignition and propagation of the ionization front in the dielectric tube (figure 4). In the second condition, there are no air gases at the tube exit and therefore the gas composition (He with 10 ppm N 2 ) is spatially uniform, as in Du et al (2020) [203]. In that case there is no radial confinement of the discharge in the plume region, as verified in Breden et al (2012) [123].…”

“…Further details on these numerical simulations are given in [145]. Atmospheric pressure point-to-plane discharges in He with small amounts of N 2 have been studied by Brok et al (2005) [188] and by Sakiyama and Graves (2006) [189] considering RF applied voltages but no transient discharge dynamics, and in simulations by Du et al (2020) [203] considering constant applied voltage and transient discharge dynamics.…”