Plasma propagation and standing waves in spiral microplasma channels

Summary form only given. Plasma propagation in a microplasma channel having the form of a spiral has been studied in the rare gases and gas mixtures. Microchannels having widths of 200–300 µm, and a length-to - width aspect ratio of ∼10³∶1, have been fabricated in nanoporous Al2O3 by a sequence of wet chemical and micropowder machining processes, Produced from 125–250 µm thick aluminum foil, these channels are situated in a dielectric barrier structure having Al electrodes straddling the Al2O3 channel. For the experiments reported here, the channels are formed (by photolithographic patterning) into a spiral having an overall diameter of 3 cm.