Numerical studies of atmospheric pressure glow discharge controlled by a dielectric barrier between two coaxial electrodes

The glow discharge in pure helium at atmospheric pressure, controlledby a dielectric barrier between coaxial electrodes, is investigatedbased on a one-dimensional self-consistent fluid model. By solvingthe continuity equations for electrons, ions, and excited atoms, withthe current conservation equation and the electric field profile, thetime evolution of the discharge current, gas voltage and the surfacedensity of charged particles on the dielectric barrier arecalculated. The simulation results show that the peak values of thedischarge current, gas voltage and electric field in the first halfperiod are asymmetric to the second half. When the current reachesits positive or negative maximum, the electric field profile, and theelectron and ion densities represent similar properties to thetypical glow discharge at low pressures. Obviously there exist acathode fall, a negative glow region, and a positive column. Effectsof the barrier position in between the two coaxial electrodes and thedischarge gap width on discharge current characteristics are alsoanalysed. The result indicates that, in the case when the dielectriccovering the outer electrode only, the gas is punctured earlierduring the former half period and later during the latter half periodthan other cases, also the current peak value is higher, and thedifference of pulse width between the two half periods is moreobvious. On reducing the gap width, the multiple current pulsedischarge happens.