The Electrical Asymmetry Effect (EAE) is a new concept to achieve separate control of the mean ion energies and ion fluxes at the electrodes of capacitively coupled radio frequency (CCRF) discharges. By applying a fundamental frequency and (at least) one even harmonic, the symmetry of the applied voltage waveform and, thus, the symmetry of the discharge can be controlled by adjusting the phase shift between the driving harmonics. Here, this concept is further optimized by adding more consecutive harmonics to the applied voltage waveform. Furthermore, a criterion for the optimum choice of the relative amplitudes of these harmonics is given. In the results of PIC/MCC simulations, it is found that the control range of the mean ion energy at the electrode surfaces is several times larger in multi frequency compared to dual frequency electrically asymmetric discharges.
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