Cold atmospheric plasmas in rare gas jets: from metastables species to biomedical and material applications

Cold atmospheric pressure plasmas in rare gas jets (CAPPJ) have been extensively studied and used both because of their flexibility of uses and their ability to produce a wide range of reactive species of interest. CAPPJ are usually obtained using dielectric barrier discharge (DBD) reactors fed with rare gases (mostly He and Ar) and driven by pulsed or sinusoidal high voltages. The physical mechanism of plasma creation in CAPPJ is attributed to the generation and propagation of guided streamers, which are confined in the rare gas channel flowing through a thin dielectric tube and penetrating into the ambient air. These plasma devices allow to target a large panel of applications, e.g. in biomedicine, decontamination and depollution, analytical chemistry and material processing. CAPPJ are challenging for experimental and numerical fundamental studies because of the need of highly time- and space-resolved non-intrusive characterization techniques and the coupling of phenomena resulting from different timescale features covering several orders of magnitude. Also, several applications of these plasma devices require their characterization in the presence of different targets. In this talk, recent insights gained from advanced optical diagnostics of CAPPJ will be discussed, focusing on the study of the interaction between the plasma and the gas flow, and the plasma and dielectric and liquid targets, with illustrations of applications to material and cancer treatments.