Microwave plasma generation using evanescent waves

Abstract

Analysis and comparison of possible design features of microwave low-temperature plasma generators, which are based on evanesсent waves, was carried out in this paper. Three approaches which provide excitation of evanescent wave are discussed: excitation based on below cutoff waveguide; evanescent wave which is excited by surface waves; evanescent wave which is excited near the surface of the dielectric based on effect of violation of total internal reflection. These three methods make it possible to get the evanescent wave for generation of gas-discharge plasma. Equipment and technology based on these methods are not fully studied yet and required analysis and improvements. The results of this study could be applied in new designs and processes in the field of treatment of the surface layer of solids. The results of the first experiments using such generators are presented in this paper and prospects of further applications for ion-plasma treatment of the surface layer of solids (deleting, printing material and surface modification) are determined. The issue of microwave plasma generation and other technological processes based on evanescent waves is extremely important. The cause of that is their concern of various branches of science and technology including plasmonics, nanoelectronics, optics and they are widely discussed in recent years. By analogy with the effects in optics, evanescent waves can cause similar effects in gas-discharge technology. “Evanescent waves” – separate direction in electrodynamics associated with the study of these waves: their properties and possibilities of their application. Now this trend is taking on widespread development, especially in nanophotonics (excitation of plasmon oscillations and waves of plasmon polariton type). In this paper, the possibility of using the evanecent mode of the microwave waves for excitation of plasma formation is considered.Also in the paper was devoted the attention to prototyping of microwave generators that will provide the technological requirements for the surface treatment of solids and deposited coatings, giving competitive results, thus are environmentally safe, easy-to-work and relatively inexpensive design on the market. On the basis of the research, propositions of the future developing in this direction are put forward. The aim of the study is providing homogeneity zone of the surface under treatment of solid body with surface area of up to square meters, which could be used in flat-panel displays, presentation screens, solar panels, etc. Ref. 13, fig. 6.