Gas temperature and air fraction diagnosis of helium cold atmospheric plasmas by means of atomic emission lines

In this work, we present a new method allowing the determination of both the gas temperature and the air fraction in non-thermal atmospheric helium plasmas. This new UV-Atomic Emission Spectroscopy technique based on the measurement of the collisional broadening of the He I 667.82 nm and He I 728.13 nm emission lines is a particularly sensible method under low gas temperature conditions; hence it is particularly suitable for the diagnosis of cold helium atmospheric plasmas of biomedical use. To quantify the unknown amount of air entering these plasma jets is key to understanding the chemistry in them and the basis of their clinical and biological action, as it determines the amount of reactive oxygen and nitrogen they generate. The method has been applied to diagnose microwave helium plasmas generated inside three different reactors, thus in environments with different air contents.

Automated summary

In this study, a new method for determining both the gas temperature and the air fraction in non-thermal atmospheric helium plasmas is presented. This technique, based on UV-Atomic Emission Spectroscopy and the measurement of collisional broadening of specific emission lines, is particularly sensitive under low gas temperature conditions and suitable for diagnosing cold helium plasmas used in biomedical applications. Quantifying the air content is crucial for understanding the chemistry and clinical effects of these plasmas.