Propagation-decay characteristics of locally ionized microplasma packets in arrays of microchannels

Summary form only given. Plasma propagation and its decay properties in an array of microscale channels has been investigated at atmospheric pressure in He and Ar. Microplasmas in channels having a width of 200-300 μm, a length to width aspect ratio of up to ~ 10³: 1, and a volume of 1-50 mm³ have been generated by micromachining and wet chemical processes, these channels are situated in a dielectric barrier structure fabricated in 125-250 μm thick Al foil. Spatiotemporally-resolved optical emission profiles, recorded with a gated CCD camera and a telescope, reveal a plasma optical interaction with neighboring channels and propagation speed (and direction of excited emission along the microchannel) which varies with gas mixture. In Ar 760 Torr, propelled by the accumulation of charge on the microchannel wall, packets of low temperature, nonequilibrium plasma propagate at a uniform velocity of ~20 km-s^-1. The dominant mechanism for volumetric electron loss to be dissociative recombination.