Arrays of nonequilibrium plasmas confined to microcavities: an emerging frontier in plasma science and its applications

A new realm of plasma science has been entered recently with the demonstration of devices in which a nonequilibrium, low temperature plasma is produced within, and essentially confined to, a microcavity having a characteristic dimension (d) between 10 and 100 mu m. This development has introduced glow microplasmas exhibiting unique properties with respect to, for example, specific power loading and operation at atmospheric pressure (and beyond). Of equal import is the reduction of d below 100 lambda(D) (where lambda(D) is the Debye length), and the associated weakening of charge quasineutrality as well as the growing importance of plasma-wall interactions are evident. The general properties of several microcavity plasma devices occupying this region of parameter space are briefly described here, but recent experimental results with arrays (as large as 30 x 30) of Al/Al2O3 devices are emphasized. Several potential applications of single microcavity plasma devices and planar arrays are also discussed.