Characteristic of atmospheric pressure plasma jet in coplanar dielectric barrier discharge

Non-thermal plasma jet at atmospheric pressure has recently attracted lots of attention because of its applications in plasma bullet or plasma plume. Thus, we studied on generating plasma jet by coplanar dielectric barrier discharge in a device driven by sinusoidal voltage. The processes of plasma discharges in both positive and negative half cycles were recorded using a high-speed ICCD (intensified charge-coupled device) camera; based on the results we estimated the velocity of plasma propagation, and investigated the influence of gas flow on the plasma development. It is shown that the plasma bullets, which have velocity in the order of 10³~10⁴ m/s, exist only outside the cathode. APPJ (atmospheric pressure plasma jet) is created by the electron beam from the cathode, and then sustained by a strong radial electric field near and outside the cathode. The gas flow influences the APPJ length in air but not the APPJ discharge, while the discharge is affected significantly by the applied voltage.