New opportunities for plasma science in nonequilibrium, low-temperature plasmas confined to microcavities: There’s plenty of room at the bottom

Nonequilibrium, low-temperature plasmas have, in just the past few years, been confined to microcavities with characteristic dimensions (d) as small as 10μm. Plasma science has thus entered a new realm of parameter space in which d is on the order of tens of debye lengths and the plasma frequency ωp∕2π is approaching 1 THz. In this previously unexplored region, plasmas display intriguing characteristics, including the loss of quasineutrality and the ability to operate continuously at atmospheric pressure and beyond. This article will briefly describe the fabrication and behavior of microcavity plasma devices realized by the adaptation of microfabrication techniques, and device structures inspired by nanotechnology. Exciting opportunities for plasma science are within reach and a few of the implications of driving d to 1μm and into the nanometer domain are discussed.