Multipeak behavior and mode transition of a homogeneous barrier discharge in atmospheric pressure helium

Numerical calculations and analyses are carried out to get a further understanding of the mechanism of the homogeneous barrier discharge with multiple current peaks per half cycle of the applied voltage in atmospheric helium by means of a one-dimensional fluid model, taking into account the primary processes of excitation and ionization. Multipeak behavior is governed mainly by the width of the discharge gap. In smaller gas gap, multiple current peaks are formed due to the increases of charge density deposited on dielectric surfaces leading to the enhancement of the induced electric field. Each current peak corresponds to a new temporally separated breakdown. The discharge modes in the case of multipeak are studied. Both Townsend and glow modes can be observed in multipeak discharge. The transition between two discharge modes is investigated in details within a wide parameter range. When the ionization level is high enough to induce the formation of a large positive space charge density near the cathode, the glow discharge occurs; otherwise, the discharge is Townsend.