Different ionization mechanisms in pulsed micro-DBD’s in argon at different pressures

In this research we analyse different plasma wave propagation mechanism of microcavity discharge in pure argon at two different pressures. Experimental results of a pulsed micro-DBD with 2 and 50 kPa argon, 180 μm gap, at room temperature, show that two distinct pressure-dependent propagation modes exist. In the low pressure regime, the discharge propagates perpendicular to the applied electric field forming distinct channels, but many vertically-oriented filaments distributed throughout the domain at high pressure discharge. And the discharge duration time in high pressure is around 5 times shorter than that in low pressure. A 2D particle-in-cell (PIC-MCC) model with chemical reactions, photoemission, and secondary electron generation, is established to investigate the formation mechanism of the two propagation modes. Models of the initial ionization processes show that there are two different breakdown mechanisms for these two pressures, where secondary emission of electrons from the dielectric is dominated either by ion impact or by photon impact. The investigation is of great significance for further reveal of the principle of microplasmas discharge