Influence of surface parameters on dielectric-barrier discharges in argon at subatmospheric pressure

The influence of the secondary electron emission coefficient, γ, and the relative permittivity, ɛ _r, of the dielectric layers on the characteristics of dielectric-barrier discharges (DBDs) is studied by means of numerical modelling and calculated results are compared with experimental data. The analysis has been performed for a geometrically symmetric, plane-parallel DBD in argon with copper electrodes covered by quartz dielectrics. A time-dependent, spatially one-dimensional fluid model involving the drift-diffusion approximation is applied for the numerical analysis of the DBD operating sinusoidally at a frequency of 24 kHz with applied voltages between 1.8 and 3.4 kV and pressures from 100 to 650 mbar. Main features of the model as well as the experimental setup and procedures are given. The modelling studies show especially the sensitivity of the results on the specific choice of γ and ɛ _r regarding the occurrence and intensity of discharge peaks, the appearance of one or more smaller peaks after the main peak, as well the establishment of a single periodic, multiperiodic or even chaotic temporal evolution of the DBD. In particular, generally good agreement between measured and calculated discharge current signals and the power dissipated in the discharge is found for γ = 0.02 and ɛ _r = 4.2. (paper)