Nonlinear skin effect in inductive discharge

Summary form only given. Reduction of capacitive coupling and transmission line effects and simplification of RF driving means with reduction of their cost have promoted the utilization of relatively low RF frequency in industrial ICP. RF frequencies between 0.4-2 MHz have become more and more preferable to traditional 13.56 MHz. Transition to ICP at a low driving frequency brings about a variety of non-linear phenomena associated with the RF magnetic field acting in the skin layer of an ICP. We report on a comparative study of a near-collisionless ICP driven over a wide range of frequencies between 13.56-0.45 MHz. The experiments were conducted in a cylindrical discharge chamber with a flat induction coil. The working gas was argon at 1m Torr and RF power dissipated in plasma was 200 W. Space distribution of the basic plasma parameters electron density, electron temperature, plasma potential and EEDF were measured with a Langmuir probe while the electromagnetic field and current density distribution were measured with a magnetic probe. Our measurements at low driving frequencies show that the RF Lorentz force in the skin layer is much larger than the force acting on electrons in the discharge maintaining RF electric field.