Kiel 2011 – scientific programme

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P: Fachverband Plasmaphysik

P 1: Niedertemperaturplasmen / Grundlagen

P 1.2: Talk

Monday, March 28, 2011, 16:55–17:10, HS H

Power absorption in electrically asymmetric discharges — •Edmund Schüngel¹, Julian Schulze^1,2, Zoltan Donkó², and Uwe Czarnetzki¹ — ¹Institute for Plasma and Atomic Physics, Ruhr-University Bochum — ²Research Institute for Solid State Physics and Optics, Hungarian Academy of Sciences

The Electrical Asymmetry Effect allows to control the symmetry of capacitive radio frequency discharges. Here, a fundamental frequency and its second harmonic are applied to the powered electrode. In such electrically asymmetric discharges the mean ion energies at both electrodes are controlled separately from the ion flux by tuning the phase angle θ between the harmonics, while the voltage amplitudes are kept constant. The power absorbed by the electrons, P_e, is investigated as a function of θ and time experimentally, by a Particle in Cell simulation, and an analytical model. The results show, that the dynamics of P_e is strongly affected by the choice of θ. However, on time average P_e is almost constant for all θ. In conclusion, the plasma density and the ion flux are nearly constant independent of θ. The power absorbed by the ions is also constant, since the sum of the absolute values of the individual voltages across the powered and grounded electrode sheath remains constant. Thus, the total power absorbed by the discharge does not depend on θ. This might be important for applications, where usually the applied power is kept constant.