Measuring the air fraction and the gas temperature in non-thermal argon plasma jets through the study of the air influence on the collisional broadening of some argon atomic emission lines

Abstract

Cold atmospheric argon plasma jets have shown to be very promising in medicine and they are being currently used for therapeutical uses such as the healing of wounds or the treatment of tumors. Because they run in the open atmosphere, they generate copious amounts of reactive oxygen and nitrogen species, which play an outstanding role in their biological action. But, in this kind of reactor, unknown amounts of air enter the plasma region depending on the experimental conditions, changing the chemistry in them, and eventually their effects. In this work, we propose a new spectroscopic method to measure the amount of air in argon non-thermal (including cold atmospheric) plasma jets through the collisional broadening of Ar I 840.86 and Ar I 842.46 nm emission lines. The method allows the simultaneous determination of the gas temperature. For validation purposes, it was applied to a microwave-induced plasma jet working at different operational conditions. Results were consistent with those obtained from the rotational temperature derived from simulations of N2 (2nd positive system) rovibrational band.