Perturbation and coupling of microcavity plasmas through charge injected into an intervening microchannel

Coupling between two microcavity plasmas in a symmetric, microfabricated dielectric barrier structure has been observed by injecting charge from one of the plasmas into an intervening microchannel. Periodic modulation of the electric field strength in the injector (or electron "donor") cavity has the effect of deforming the acceptor microplasma which exhibits two distinct and stable spatiotemporal modes. Throughout the time interval in which the two microplasmas are coupled electrostatically, the acceptor plasma is elongated and displaced by 75-100 μm (∼30% of its diameter) in the direction of the microchannel. The depletion of charge in the microchannel results in an immediate transition of the second (acceptor) microplasma to an equilibrium state in which the plasma is azimuthally symmetric and centered within its microcavity. Switching between these two spatial modes requires a shift (in the plasma centroid) of ∼80 μm in <50 ns which corresponds to a velocity of 1.6 km/s. Precise control of this plasma phase transition through device fabrication, and modulation of the donor plasma electric field, suggest applications of this plasma coupling and charge transport mechanism to signal processing, photonics, and electromagnetics.