Michel Moisan

Abstract Utilizing a plasma to achieve sterilization is a possible alternative to conventional sterilization means as far as sterilization of heat-sensitive materials and innocuity of sterilizing agents are concerned. A major issue of plasma sterilization is the respective roles of ultraviolet (UV) photons and reactive species such as atomic and molecular radicals. At reduced gas pressure (£10 torr) and in mixtures containing oxygen, the UV photons dominate the inactivation process, with a significant contribution of oxygen atoms as an erosion agent. Actually, as erosion of the spore progresses, the number of UV photons successfully interacting with the genetic material increases. The different physicochemical processes at play during plasma sterilization are identified and analyzed, based on the specific characteristics of the spore survival curves.

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.

International audience

1. Introduction (M. Moisan, J. Pelletier). 2. Physical principles of microwave plasma generation (C.M. Ferreira et al.). 3. Kinetic modelling of microwave discharges: Influence of the discharge stimulating frequency (C.M. Ferreira, M. Moisan). 4. Plasmas sustained within microwave circuits (Z. Zakrzewski et al.). 5. Surface-wave plasma sources (M. Moisan, Z. Zakrzewski). 6. Principles of magnetically assisted microwave discharges (J. Margot et al.). 7. Operation and properties of magnetically assisted high frequency discharges intended for applications (J. Margot, R.A. Gottscho). 8. Surface wave sustained plasmas in static magnetic fields for the study of ECR discharge mechanisms (J. Margot, M. Moisan). 9. Interest of plasma confinement and its limits (J. Pelletier et al.). 10. Discharges confined by multipolar magnetic fields (R. Burke, J. Pelletier). 11. Ambipolar diffusion model of multipolar plasmas (G. Matthieussent, J. Pelletier). 12. Homogeneity in multipolar discharges: The role of primary electrons (J. Pelletier, G. Matthieussent). 13. High frequency sustained multipolar plasmas (C. Pomot, J. Pelletier). 14. Distributed electron cyclotron resonance (DECR) plasmas (M. Pichot, J. Pelletier). 15. Applications of microwave plasmas in microcircuit fabrication (J. Paraszczak, J. Heidenreich). Index of symbols. Index.