Numerical simulation on the characteristics of a micro-hollow cathode discharge with external surface of the cathode covered by a dielectric layer

Abstract

Being able to generate a plasma denser than that in the usual micro-hollow cathode discharge device (MHCD), a MHCD with the cathode outer surface covered by a dielectric layer has been numerically simulated in atmospheric pressure helium with a two-dimensional fluid model in this paper. Results indicate that before reaching a steady state, the covered MHCD sequentially undergoes three phases. In the initial phase, a strong discharge and a weak discharge appear in the vicinities of the cathode and the anode, respectively. Then, a positive streamer propagates along the axis from the anode to the cathode. After that, the entire gap between the two electrodes is filled with discharges. In addition, the evolution of averaged densities is given for various species. Moreover, voltage and current curves are compared for the covered and uncovered MHCDs in the steady state. As expected, the covered MHCD has an averaged electron density higher than that of the uncovered MHCD in the steady state. These results are helpful in generating an atmospheric pressure plasma with high electron density, which is important for the extensive applications of MHCD.

Numerical simulation and experimental diagnostics of fast electron kinetics and plasma parameters in a microhollow cathode discharges in helium

“…However, it should be noted that fluid models [25][26][27][28][32][33][34][35] do not take into account nonlocal ionization by fast electrons in negative glow plasma in short glow discharges and discharges with a microhollow cathode. The main consequence of the nonlocality of the ionization source in the negative glow region is that the electric field strength in this region takes values close to zero, and the temperature of the main group of electrons is low and amounts to tenths of 1 eV [36][37][38][39].…”