Electron heating mechanisms in dual frequency capacitive discharges

We discuss electron heating mechanisms in the sheath regions of dual-frequency capacitive discharges, with the twin aims of identifying the dominant mechanisms and supplying closed-form expressions from which the heating power can be estimated. We show that the heating effect produced by either Ohmic or collisionless heating is much larger when the discharge is excited by a superposition of currents at two frequencies than if either current had acted alone. This coupling effect occurs because the lower frequency current, while not directly heating the electrons to any great extent, strongly affects the spatial structure of the discharge in the sheath regions

Collisionless heating in radio-frequency discharges: a review

Radio-frequency discharges are practically and scientifically interesting. A practical understanding of such discharges requires, among other things, a quantitative appreciation of the mechanisms involved in heating electrons, since this heating is the proximate cause of the ionization that sustains the plasma. When these discharges are operated at sufficiently low pressure, collisionless electron heating can be an important and even the dominant mechanism. Since the low pressure regime is important for many applications, understanding collisionless heating is both theoretically and practically important. This review is concerned with the state of theoretical knowledge of collisionless heating in both inductive and capacitive discharges