Two-dimensional simulation of ac-driven microplasmas confined to 100–300μm diameter cylindrical microcavities in dielectric barrier devices

Cylindrical microcavity plasma devices with diameters (D) in the 100–300μm range and a dielectric barrier structure similar to that described by Park et al. [J. Appl. Phys. 99, 026107 (2006)] for Al∕Al2O3 devices have been investigated numerically. A two-dimensional fluid simulation of microplasmas in Ne/7% Xe gas mixtures with pD values (where p is the total gas pressure) in the 3–9Torrcm interval yields the temporal history of the spatially resolved electron and ion number densities in response to a 250kHz bipolar excitation wave form. Calculations show two distinct regions of plasma development, along the microcavity axis and near the wall, each of which dominates the plasma characteristics in separate pD regions. For low pD values (<4Torrcm), the negative glow produced at the cavity wall extends to the microcavity axis which, in combination with the strong axial electric field, produces an intense glow discharge on axis. For 4≲pD≲6Torrcm, a weakened axial discharge is observed early in the life of the...