Gas temperature effects in micrometre-scale dielectric barrier discharges

A numerical modelling study of micrometre-length-scale (gap distances of ∼50–100 µm) dielectric barrier discharges (micro-DBDs) is reported. A comparison of micro-DBDs with classical large-scale DBDs (gap distances of ∼ mm) reveals the principal effect of downscaling DBD gap dimensions on the gas heating in these discharges. A one-dimensional, self-consistent, multi-species, multi-temperature continuum model is used in the simulations. For a constant pd (pressure × discharge gap distance) and applied voltage waveform (500 V, 10 MHz), a larger cycle-averaged gas temperature rise is seen in the micro-DBDs ∼hundreds of kelvin compared with much smaller rise ∼tens of kelvin in the classic DBDs. The gas temperature increase in micro-DBDs is mainly due to the rapid increase in the power densities as the gap dimensions are decreased compared with the increase in the wall loss with decreasing gap distances. For conditions studied in this work, the power densities in micro-DBDs are about four orders of magnitude larger than classic DBDs. Operation at higher frequencies, with other conditions remaining constant, is observed to favour larger gas temperatures in micro-DBDs. Micro-DBDs are therefore excellent device candidates to provide controllable gas heating in a variety of micro-electro mechanical systems; small spacecraft electrothermal micropropulsion devices being an example.