Harmonic content and time variation of electron energy distributions in high-plasma-density, low-pressure inductively coupled discharges

Plasma kinetics models which are commonly used to model rf discharges often produce electron energy distributions (EEDs) averaged over the rf cycle. In doing so, the time dynamics of the EEDs are lost. In this article we describe a technique to recover these time dynamics by using an "on-the-fly" (OTF) Monte Carlo method. The OTF method directly computes the harmonic content of the EEDs using Fourier transform techniques during advancement of the trajectories of pseudoelectrons. The OTF method was incorporated into a two-dimensional plasma equipment model to investigate the harmonic content of the EEDs and their time dependencies in inductively coupled low-pressure (less than or equal to10 mTorr) and low-frequency (less than or equal to16 MHz) plasmas sustained in Ar. The computational results demonstrated that the second harmonic dominates the time dynamics of the EEDs, and that this harmonic content mostly occurs at higher energies. The harmonic content at low energies is significant only in the electromagnetic skin layer. We also found that the time evolution of the second harmonic of the EED involves the simultaneous transit of several pulses in energy and space. These pulses are attributed to the nonlinear Lorentz force resulting from the rf magnetic field. (C) 2003 American Institute of Physics.