Low-pressure radio-frequency inductive discharge and possibilities of optimizing inductive plasma sources

Abstract

Plasma reactors and ion sources whose operation relies on a low-pressure radio-frequency (RF) inductive discharge have been an important constituent of modern ground and space technologies for several decades already. However, the steadily toughening and varying requirements of plasma technologies call for improving the old models of devices and developing novel prospective models. Of vital importance in the development of inductive plasma sources is the provision of conditions whereat the plasma efficiently absorbs the RF power. In recent years it has become evident that in a low-pressure RF inductive discharge the RF-generator power is distributed between the active resistance of the external circuit and the plasma. In the latter case, the power is delivered to the plasma via two channels: an inductive channel, which exists due to the current flowing through an inductor or an antenna, and a capacitive one, which is due to the antenna–plasma capacitive coupling. RF inductive discharge properties related to the RF-power redistribution between the channels are considered and the mechanisms of RF-power absorption are analyzed. The feasibilities of optimizing RF inductive plasma sources are also discussed.