Experimental and modelling investigations of a dielectric barrier discharge in low-pressure argon

The discharge behaviour of a dielectric barrier discharge (DBD) in low-pressure argon gas was investigated by experiments and modelling. The electrical characteristics and light emission dynamics of the discharge were measured and compared with the results of a two-dimensional fluid model. Our investigations showed that the discharge consisted of a single, diffuse discharge per voltage half-cycle. The breakdown phase of the low-pressure DBD (LPDBD) was investigated to be similar to the ignition phase of a low-pressure glow discharge without dielectrics, described by Townsend breakdown theory. The stable discharge phase of the LPDBD also showed a plasma structure with features similar to those of a classical glow discharge. The presence of the dielectric in the discharge gap led to the discharge quenching and thus the decay of the plasma. Additionally, the argon metastable density was monitored by measuring light emission from nitrogen impurities. A metastable density of about 5 x 10(17) m(-3) was present during the entire voltage cycle, with only a small (similar to 10%) increase during the discharge. Finally, a reduction of the applied voltage to the minimum required to sustain the discharge led to a further reduction of the role of the dielectric. The discharge was no longer quenched by the dielectrics only but also by a reduction of the applied voltage.