Numerical study of surface charge dynamics and its feedback on the interaction between atmospheric pressure plasma jet and dielectric target

Abstract The surface charge dynamics due to the interaction between a nanosecond pulsed atmospheric pressure plasma jet (APPJ) and a grounded dielectric surface is investigated by two-dimensional axisymmetric fluid simulation. The development of APPJ can be divided into three stages: (1) the primary discharge, (2) the return and forward strokes, and (3) surface ionization wave (SIW). It is verified that the forward stroke plays a critical role on the polarity of surface charges, which can be further controlled by pulse parameters (e.g. pulse width and voltage amplitude). The enhanced forward stroke, characterized by an elevated electric field with a relatively uniform distribution along the APPJ channel, raises the potential drop across the plasma column and creates the conditions for the field reversal near the target. These flip the axial electric field and drive electrons moving towards the target, as a result of which, the polarity of surface charges reverses. This indicate that as the potential drop cross the plasma column exceed the applied voltage, the direction of electric field revers and can cause the polarity reversion of surface charge. Thus, the reversal instant can happen at the voltage plateau, the voltage falling edge or after the applied voltage has reduced to zero. Due to the time sequence of surface charge reversing at different radial positions, which induces a remarkable radial field component, a negative SIW further develops along the dielectric target. As feedback, this phenomenon results in both enhanced net charge transfer to the dielectric and intensive energy deposition (electron Joule heating) of APPJ in the vicinity of the target. This study opens a new route towards the application optimization of APPJ in multiple fields via the feedback effect of surface charges on APPJ-surface interaction.