Discharge phenomena of an atmospheric pressure radio-frequency capacitive plasma source

Discharge phenomena of a nonthermal atmospheric pressure plasma source have been studied. An atmospheric pressure plasma jet (APPJ) operates using rf power and produces a stable homogeneous discharge at atmospheric pressure. After breakdown, the APPJ operation is divided into two regimes, a "normal" operating mode when the discharge is stable and homogeneous, and a "failur e" mode when the discharge converts into a filamentary arc. Current and vol tage (I-V) characteristics and spatially resolved emission intensity profil es have been measured during the normal operating mode. These measurements show that the APPJ produces an alpha (alpha) mode rf capacitive discharge. Based upon a dimensional analysis using the observed I-V characteristics, a rough estimate is made for plasma density of 3 x 10(11) cm(-3) and an elec tron temperature of 2 eV. In addition, the gas temperature of 120 degreesC has been spectroscopically measured inside the discharge. These plasma para meters indicate that the APPJ shows promise for various materials applicati ons as it can produce substantial amounts of reactive species and avoid the rmal damages, while having the advantage of atmospheric pressure operation. (C) 2001 American Institute of Physics.