1D Model of the Dielectric Barrier Discharge in Ar-S2 Mixtures

A one-dimensional fluid model of a dielectric-barrier discharge (DBD) in Ar-S-2 mixtures is developed, and the properties of the discharge are modeled. The discharge in a 3-mm-long gas gap between 2-mm-thick quartz layers covering metal electrodes is considered. The DBD spatiotemporal characteristics are simulated at gas pressures of 300 Torr for the case in which a 20-kHz harmonic voltage with amplitude of 8 kV is applied to electrodes. It was shown that the discharge active phase at S-2 fraction of 0.1% in Ar-S-2 mixture is characterized by the presence of multiple current spikes, which is explained by weak ionization waves. The cycle-averaged dissociation degree of S-2 molecules is similar to 0.05-0.3% in Ar-S-2 mixture with S-2 fraction of 0.1-1% and degree of gas ionization is 2 x 10(-8)-4 x 10(-7). The plasma is electronegative due to the fast attachment of electrons to sulfur molecules: e + S-2 -> S-2(-). The radiative efficiency of S-2* excited molecules at S-2 fraction of 0.5 and 1% is about two times higher than at S-2 fraction of 0.1% and reaches about 0.8%. At S-2 content in Ar-S-2 mixture of 0.1% the main contribution in the discharge emission make argon resonance atoms (70%), while at 1%S-2 the main contribution in the emission make sulfur excited atoms (95%), which radiative efficiency abruptly increases. The optimal S-2 fraction in Ar-S-2 mixture for developing DBD radiation source based on emission of S-2* molecules is about 0.5%, when the 98% of discharge emission distributes between Ar* (44%), S-2* (42%) and Ar-2* (12%).

Automated summary

A one-dimensional fluid model of dielectric-barrier discharge in Ar-S-2 mixtures was developed and simulated at a gas pressure of 300 Torr. The discharge active phase at 0.1% S-2 fraction in the mixture is characterized by multiple current spikes, with a cycle-averaged dissociation degree of S-2 molecules ranging from 0.05% to 0.3%.