Energy efficiency of voltage waveform tailoring for the generation of helium metastable species in RF plasma jets *

Atmospheric pressure capacitively coupled radio frequency discharges operated in He/N₂ mixtures and driven by single frequency as well as tailored voltage waveforms are investigated using a reference microplasma COST-jet.  For each case, the dissipated power is measured based on a careful calibration procedure of voltage and current measurements. The results are compared to PIC/MCC simulation results and a very good agreement is found. We demonstrate that Voltage Waveform Tailoring (VWT) - in contrast to the classical single-frequency operation - does not only provide better control of the generation of metastable species (He-I 2³S₁) but also provides significantly better energy efficiency of such processes.