The article "Effect of gas properties on the dynamics of the electrical slope asymmetry effect in capacitive plasmas: comparison of Ar, H2 and CF4", Plasma Sources Sci. Technol. 25 01LT02 has been selected as a highlight of 2016 for the Plasma Sources Science and Technology journal.
Production of plasmas for materials processing via waveforms consisting of a sum of harmonics has recently been proposed as an efficient way to break the link between the plasma density (process rate) and the ion energy flux to a surface (substrate damage). These waveforms produce unexpected spatiotemporal trends in the physics and the chemistry of the reactor. In the framework of an international collaboration a combined computational-experimental study of a geometrically symmetric capacitively coupled plasma was performed in Ar, H2 and CF4, gases with different properties, leading to fundamental differences in the electrical spatial asymmetry of discharges excited with the same sawtooth waveform. The spatiotemporal distribution of the dominant electron energy gain mechanism is identified as the main cause for these asymmetries.
Authors of the paper are B. Bruneau, T. Lafleur, T. Gans, D. O'Connell, A. Greb, I. Korolov, A. Derzsi, Z. Donkó, S. Brandt, E. Schüngel, J. Schulze, P. Diomede, D. J. Economou, S. Longo, E. Johnson and J.-P. Booth.
Excitation rate obtained from the experiments (first column), and from the simulations (second column), spatiotemporal plots of the electric field (third column), and electron power absorption rate (fourth column), from the simulations, for an argon discharge (top row), a hydrogen discharge (middle row), and a carbon tetrafluoride discharge (bottom row).