Plasma-substrate interaction in a dual frequency APPJ

The Argon plasma produced in a coaxial jet by a pair of high frequency (HF 17 kHz) electrodes and a downstream ring radiofrequency electrode (RF 27.12 MHz) were investigated by means of 2D simulations and electrical and optical characterizations. As ignited, the plasma spreads to the facing surfaces and couples the HF and RF electrodes, even if positioned a few cm apart from each other. As a result, the HF to drive ions to the substrate while the RF allows to sustain the plasma while limiting the current density.