Atmospheric pressure plasma jets in contact with a dielectric surface:the electric field and the charge at the surface

Atmospheric pressure plasma jets are in the current research focus, as they are cheap and simple to make, yet have shown tremendous potential in material modification or biomedical applications. The common point is the presence of a target in the effluent of the jet. Targets can be metallic, dielectric or made of biological material, however in all cases they modify the plasma to a certain extent and it is therefore necessary to perform research on non-thermal atmospheric pressure plasma sources in the presence of a target.The focus of this paper is the interaction of a kHz helium plasma jet and a dielectric target, more precisely the electric field and the charge at the surface of the target. The Pockels’ method was used to measure the electric field on the surface between 3 mm and 10 mm away from the nozzle of the plasma jet, as a function of the gas flow and applied voltage. The obtained field is of the order of magnitude of 105 V/m.