Differences of voltage and current driven capacitiveley coupled plasmas in particle-in-cell simulations
Sebastian Wilczek, Jan Trieschmann, Ralf Peter Brinkmann, Thomas Mussenbrock
WELTPP-18, December 3-4, 2015 at Rolduc, Kerkrade, the Netherlands
An immediate question in numerical simulations of capacitive coupled radio frequency (ccrf) discharges is: What is the influence of the driving source in current vs. voltage driven discharges? Especially, the theory of the self-excitation of the plasma series resonance (PSR) by the nonlinearity of the plasma sheath is inconsistent when using a current source. A sinusoidal radio frequency current is coupled into the discharge, and is locally divided into a displacement and a conduction current. Since it is purely sinusoidal, no harmonics in the total current density arise and the self-excitation of the PSR would not be allowed. However, harmonics in the conduction current can still appear. These are locally fully compensated by the displacement current (plasma parallel resonance). In this work the spatio-temporal distribution of the conduction and the displacement current density is investigated comparing the influence of a voltage and a current source. Significant differences between both sources are discussed in detail in conjunction with resonance phenomena and nonlinear electron dynamics. The results are calculated by means of Particle-In-Cell simulations.