Effects of the Operating Conditions on the Electrical Characteristics of Pulse Discharges in Atmospheric-Pressure Pure Helium

In this paper, the effects of operating conditions on the electrical characteristics in a dielectric barrier discharge excited by voltage pulses are systematically investigated by means of a 1-D fluid model. The operating conditions refer to barrier fashion, secondary electron emission coefficient gamma, gap width d(g), dielectric constant epsilon(r), and dielectric thickness d(s). Under different operating conditions, the important characteristic quantities of describing the pulse discharges, i.e., discharge current density J(g), breakdown voltage V-b, averaged electron density N-ave, averaged dissipated power density P-ave, and axial distributions of both electron density N-e and electron temperature T-e, are calculated and analyzed in detail. The present work gives the following significant results. There are almost no effects of the operating condition on the characteristic quantities except for the amplitude of J(g) in the first discharge if the accuracy of the model is taken into account. The peak value of N-e nearby the momentary cathode (MC) becomes larger, and large N-ave can be obtained by small P-ave by increasing. of the MC. For small dg, the breakdown of the gap occurs earlier, and for large dg, both the small peak value of N-e and the wide area of quasi-neutral plasma bulk can be obtained. All of the parameters except for V-b in the second discharge decrease, the peak value of N-e nearby the MC gets smaller, and the T-e in the cathode sheath presents lower, when decreasing epsilon(r) or increasing d(s).