Plasma sources based on the propagation of electromagnetic surface waves

Abstract

Microwave and RF plasmas are finding increasing use in materials processing, plasma chemistry, chemical analysis, and other fields. This is stimulating the search for suitable plasma sources. In the 1970s, electromagnetic surface waves were put to use to sustain plasmas and an efficient microwave device, called a surfatron, was developed for this purpose. Recent work has shown that such discharges can also operate at radio frequencies. A large number of on surface-wave plasmas experimental data have been accumulated-their modelling is well advanced and they have found applications in various fields of research and technology. This paper reviews the physical principles of operation and the design of surface-wave plasma sources. Since the wave launcher is the central component of the source, this review presents a unified description of several compact, efficient, and easy to operate launchers specifically intended for plasma generation that have been developed over the past fifteen years. It is now possible to sustain such plasmas at frequencies ranging from 1 MHz to 10 GHz, in a pressure domain extending from 10^-5 Torr up to few times atmospheric pressure, and in a rich variety of plasma vessels and reaction chambers.