Numerical modelling of atmospheric pressure gas discharges leading to plasma production

Abstract

In this paper, we give a detailed review of recent work carried out on the numerical characterization of non-thermal gas discharge plasmas in air at atmospheric pressure. First, we briefly describe the theory of discharge development for dielectric barrier discharges, which is central to the production of non-equilibrium plasma, and we present a hydrodynamic model to approximate the evolution of charge densities. The model consists of the continuity equations for electrons, positive and negative ions coupled to Poisson's equation for the electric field. We then describe features of the finite element flux corrected transport algorithm, which has been developed to specifically aim for accuracy (no spurious diffusion or oscillations), efficiency (through the use of unstructured grids) and ease of extension to complex 3D geometries in the framework of the hydrodynamic model in gas discharges. We summarize the numerical work done by other authors who have applied different methods to various models and then we present highlights of our own work, which includes code validation, comparisons with existing results and modelling of radio frequency systems, dc discharges, secondary effects such as photoionization and plasma production in the presence of dielectrics. The extension of the code to 3D for more realistic simulations is demonstrated together with the adaptive meshing technique, which serves to achieve higher efficiency. Finally, we illustrate the versatility of our scheme by using it to simulate the transition from non-thermal to thermal discharges.We conclude that numerical modelling and, in particular, the extension to 3D can be used to shed new light on the processes involved with the production and control of atmospheric plasma, which plays an important role in a host of emerging technologies.

On the transition from stable positive glow corona to streamers

“…since it can cause power energy loss, audible noise and insulation damage [2]. On the other, applications of corona discharges at atmospheric pressure are emerging in areas such as the ozone production, surface treatment, pollution control, thinfilm deposition, etc [3].…”

“…However, kinetic models are highly time-consuming. The other alternative method is to consider a fluid approximation of the plasma, which is computationally more efficient and therefore is widely used in the literature [3,18]. The fluid model of gas discharges is defined by several continuity equations coupled with Poisson equation.…”

Pulse shape influence on the atmospheric barrier discharge

“…which is low in power consumption because it is a short current pulse, with an amplitude 100 times smaller than for the rf discharge. 10 Figure 1 demonstrates that generating a DBD plasma with a rectangular voltage ͑3͒ or with a pulsed dc profile ͑4͒ using frequencies of 10 kHz and peak-to-peak voltages of 4 kV generates the same plasma which exhibits a current pulse of 230 mA/ cm 2 right after a gap voltage of 3.4 kV is reached.…”

Ion-impact secondary emission in negative corona with photoionization

“…Subscripts of e, p, n denote electron, positive ion and negative iron, respectively. The swarm parameters in Table I obtained by Kang were utilized in our simulations which were verified by Tran and summarized by Georghiou et al 25,26 i is the Trichel pulse current and V a the applied voltage. 27 Ω denotes the volume of formed by revolving the computation domain along the symmetry axis.…”

“…25,26,[28][29][30] However, it is more efficiently to solve the three-exponential Helmholtz equations to obtain the distribution function of photon generation rate. 23…”