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J. Laimer:
"Recent advances in the research on non-equilibrium atmospheric pressure plasma jets";
Vortrag: 10th Intern. Conf. on Plasma Surface Engineering (PSE), Garmisch-Partenkirchen/D (eingeladen); 13.09.2006.

Recently, there has been increased interest in using atmospheric pressure plasmas for materials processing, as these plasmas may not require expensive vacuum systems. However, thermal atmospheric plasmas produced by torches cannot be used for heat-sensitive substrates. Contrary to that, non-equilibrium atmospheric plasmas seems to be best suited for this type of applications. While atmospheric non-equilibrium plasmas using dielectric barriers are widely known and investigated, atmospheric pressure glow discharges (APGD) are a fairly recent object of study. The research group of Selwyn has introduced an atmospheric pressure plasma jet (APPJ)[1,2], which operates in a capacitively coupled configuration using radio-frequency (rf) power and produces a stable glow discharge between two metallic electrodes. This glow was identified as the alpha mode of an rf discharge. This mode is only stable up to a certain power limit, where a transition to another discharge mode occurred. Depending on the conditions used this mode was most recently identified as either a pure gamma mode of an rf discharge or a coexisting alpha and gamma mode [3].
Basically, three geometric configurations of APPJ´s have been developed. The first one uses concentric electrodes similar to conventional torches, producing a narrow circular effluent (point source). The second one uses two solid plane electrodes, where the gas passes through the discharge in the gap and produces an effluent with a rectangular cross section (line source). The third one uses planar grid electrodes allowing a gas flow through the electrodes, producing an effluent with a rather wide cross section (plane source).
[1] J. Park, I. Henins, H. W. Herrmann, G.S. Selwyn, J. Appl. Phys. 89 (2001) 15.
[2] J. Park, I. Henins, H. W. Herrmann, G.S. Selwyn, R.F. Hicks, J. Appl. Phys. 89 (2001) 20.
[3] J. Laimer, S. Haslinger, W. Meissl, J. Hell, H. Störi, Vacuum 79 (2005) 209.