Experimental investigation in the recombination zone of an RF atmospheric pressure plasma jet

The present paper deals with investigations in the recombination zone or effluent of a low-frequency (kHz-range) driven atmospheric pressure plasma jet (APPJ) in argon to get a better understanding of the physical effects. The main aim was to study the possibility to detect the 4s(
³
P
₂
) metastable atoms by diode laser absorption spectroscopy at very short absorption length in the range of tenth of millimetre. Moreover, it was of interest to reveal the axial structure of the metastable densities of the effluent. Additionally, the temporal behaviour of the spatial structure of the plasma jet is also investigated by means of an intensified video camera and the results provide values of the propagation velocity of the effluent.