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J. Laimer, H. Störi:
"Glow Discharges Observed in Capacitive Radio-Frequency Atmospheric-Pressure Plasma Jets";
Plasma Processes and Polymers, 3 (2006), 8; 573 - 586.

Summary: The APPJ is the subject of intensive recent research. Basically, the APPJ consists of an atmospheric-pressure RF discharge between two bare metallic electrodes and of a superimposed gas flow consisting predominantly of a rare gas. In its usual operating regime, a uniform glow discharge, which was identified as the mode of a RF discharge, can be sustained over a wide range of gap spacings and RF powers. Maximum electron densities of 0.22 × 1012 cm-3 were assessed for helium and of 2.75 × 1012 cm-3 for argon by evaluation of electric measurements using a simple equivalent circuit model. At low RF powers, only partial coverage of the electrodes was observed. At high RF powers, a breakdown of the sheath occurred, and a transition to either a pure mode or a coexisting and mode took place. The mode covers only a small fraction of the electrode surface. In helium, it was easy to ignite directly a pure discharge, but not in argon. Due to the high over-voltage needed, the ignition in argon mostly led to a coexisting and mode. However, through RF power reduction a transition to a pure discharge can be initiated.

atmospheric pressure glow discharges (APGD) . atmospheric pressure plasma jets (APPJ) . nonthermal plasma . radio-frequency glow discharges (RFGD)