RF B-field effects in inductive plasma sources

Summary form only given. For inductive plasma sources, the RF electric field E/sub rf/ decays going into the plasma owing to the skin effect and finite geometry. This short scale length gives rise to a strong RF magnetic field B/sub rf//spl prop/1/f, where f is the RF frequency. The resulting qv/spl times/B/sub rf/ force for electrons typically exceeds the qE/sub rf/ force for f/spl les/14 MHz. In the linear regime (/spl nu//sub rf//spl Lt//spl nu//sub thermal/), the magnitude of the collisionless (or stochastic) heating for an isotropic distribution is not changed by B/sub rf/, but it does cause the energy to be deposited primarily in the velocity component along E/sub rf//spl times/B/sub rf/ rather than along E/sub rf/. In the nonlinear regime, B/sub rf/ can stop most of the electrons before they reach the wall sheath, with an effect that is qualitatively like a ponderomotive potential. Here the collisionless heating level is reduced below that predicted from linear theory. Analytical results are given for the for the nonlinear regime when the transit time is either small or large compared to the wave period, and linear regime with arbitrary transit time, and compared to numerical results. Numerical results with a self-consistent DC potential show improved plasma uniformity, as expected from the ponderomotive-like effect. Collisions in the field region can modify these results; this is explored numerically by adding a model for pitch-angle scattering.