Effect of jet polarity on charging of a dielectric target: simulations and experiments

The dynamical charging of a dielectric BSO target by an atmospheric pressure low-temperature plasma jet is addressed numerically and experimentally, using a two-dimensional fluid model and Mueller polarimetry measurements. The jet geometry is the same in experiments and simulations. The target is placed perpendicularly to the jet propagation and the jet is powered by rectangular pulses of applied voltage of different polarity and magnitude. The axial component of electric field inside the target is quantitatively compared between simulations and experiments, yielding excellent agreement for every studied condition, during and after the pulses. The electric field inside the target is closely related to the charge deposition on the target surface. It is shown that the spatial distribution of electric field inside the target during the pulse takes a different shape according to the jet polarity. Shortly after the pulse, charge deposition of opposite signal to the one of the applied voltage takes place. Finally, in the long time-scales in between pulses, the distributions of leftover surface charges on the target surface and leftover electric field inside the target are dependent on the polarity and magnitude of applied voltage. The discharge dynamics and the reasons behind these differences are investigated.