VI Int. Workshop on Microwave Discharges: Fundamentals and Applications

September 11-15, 2006, Zvenigorod, RUSSIA

RF and Microwave plasma sources using linear-field-applicators based on stripline technology

J. Pollak, M. Moisan, Z. Zakrzewski1

Groupe de physique des plasmas, Université de Montréal, Montréal, Québec
1Polish Academy of Sciences, Gdańsk, Poland

High frequency (HF) generated plasmas that extend over large distances compared to the free-space wavelength are usually sustained by the propagation of surface waves. Linear applicators running along the discharge tube can also produce long plasma columns [1]. To date, these linear applicators are mainly based on coaxial or waveguide technology. Planar TEM transmission lines can also be designed as linear field applicators. We have worked out a novel HF structure, using the stripline technology, which allows a plasma column or a group of them to be sustained through the propagation of an electromagnetic guided-wave. Our presentation is centered on the electrodynamic characteristics of these plasma sources. No tuning system is required to achieve an efficient power transfer to the plasma. The discharges have been analysed by comparison with surface-wave discharges (SWDs) sustained under the same operating conditions. Lower plasma density than with SWDs can be obtained which provides a lower gas temperature and a longer plasma column for the same absorbed power. Plasma homogeneity has been studied up to atmospheric pressure in argon. Contraction and filamentation of these discharges [2] are observed at high pressures and the interaction between these phenomena and the gas flow are presented. The possibility of operating at lower gas temperature than with SWDs is of interest for processing thermosensitive materials, for example, for sterilization purposes [3].

References

  1. Z. Zakrzewski, M. Moisan, Plasma Sources Sci. Technol., 1995, 4, 379.
  2. Y. Kabouzi. M. D. Calzada, M. Moisan, K. C. Tran, C. Trassy, J. Applied Phys., 2002, 91, 1008.
  3. J. Pollak, M. Moisan, B. Saoudi, Z. Zakrzewski , patent application (PCT), WO 2004/050128, 2004.