Energy efficiency of voltage waveform tailoring for the generation of excited species in RF plasma jets operated in He/N${}_2$ mixtures

Abstract

Based on Tunable Diode Laser Absorption Spectroscopy (TDLAS) measurements of the spatially averaged and peak helium metastable atom densities in a capacitively coupled micro atmospheric pressure plasma jet operated in He/N${}_2$ mixtures, the energy efficiency of metastable species (He-I 2${}^3$S${}_1$) generation is compared for three different scenarios: single frequency operation at (i) 13.56 MHz and (ii) 54.12 MHz, and Voltage Waveform Tailoring (VWT) at (iii) "valleys"-waveforms synthesized from four consecutive harmonics of 13.56 MHz. 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 very good agreement is found. The computational results show that the choice of the surface coefficients in the simulation is important to reproduce the experimental data correctly. Due to the enhanced control of the spatio-temporal electron power absorption dynamics and, thus, of the electron energy distribution function by VWT, this approach does not only provide better control of the generation of excited and reactive species compared to single frequency excitation, but in case of helium metastables the energy efficiency is also shown to be significantly higher in case of VWT.

References in corpus (6)

• Ionization by bulk heating of electrons in capacitive radio frequency atmospheric pressure microplasmas
• Multi frequency matching for voltage waveform tailoring
• Spectroscopic characterization of atmospheric pressure um-jet plasma source
• The effect of photoemission on nanosecond helium microdischarges at atmospheric pressure
• The formation of atomic oxygen and hydrogen in atmospheric pressure plasmas containing humidity: picosecond two-photon absorption laser induced fluorescence and numerical simulations
• Reproducibility of `COST Reference Microplasma Jets'

Cited by in corpus (2)

• Zero-dimensional and pseudo-one-dimensional models of atmospheric-pressure plasma jet in binary and ternary mixtures of oxygen and nitrogen with helium background
• Electron power absorption in micro atmospheric pressure plasma jets driven by tailored voltage waveforms in He/N${}_2$