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 10-5Torr up to few times atmospheric pressure, and in a rich variety of plasma vessels and reaction chambers.

Microwave plasmas applied for the synthesis of free standing graphene sheets

“…A surfatron-based setup was used to create surface wave induced microwave plasma at atmospheric pressure conditions [23]. The microwave power is provided by a 2.45 GHz generator (Sairem), whose output power was varied from 500 to 900 W. The discharge takes place inside a quartz tube with internal and external radii of 7.5 and 9 mm, respectively, which is inserted vertically and perpendicularly to the waveguide wider wall.…”

O2 dissociation in Ar–O2 surface-wave microwave discharges

“…For more details the reader should refer to [9,[13][14][15], where the gas phase and surface reactions taken into account in the model, as well as all other parameters used, are described. A surface wave microwave discharge generated in a small diameter tube is a plasma column with a decreasing electron density profile as discussed in [16,17]. At the end of plasma column the electron density reaches a value n ec corresponding to the critical density for surface wave mode propagation in a homogeneous, cold, collisionless plasma, surrounded by a dielectric of permittivity ǫ g .…”

Beam-Forming and Beam-Steering Capabilities of a Reconfigurable Plasma Antenna Array

“…In particular, a Gaseous Plasma Antenna (GPA) consists of a plasma discharge confined in a dielectric tube which may come in different shapes, e.g., loops or rods. On the other hand, depending on the intended application, the plasma can be generated by feeding EM power through various methods, e.g., direct-current (DC) discharge or Radio Frequency (RF) surface-waves [8,9].…”