Temporal analysis of a miniaturized plasma jet: a comprehensive study of the electrical and chemical characteristics

Due to the promising results of medical applications of atmospheric pressure plasmas (APPs), the plasma medicine research field has been growing consistently along the last two decades. Among the possible configurations for producing APPs, plasma jets are the most frequently reported in the field. Some plasma jet devices are built with flexible parts, and this allows a plasma jet to be applied exactly where it needs to be used, which leads to optimized results for its application. In this study, the initial operating period, the start-up period, of a miniaturized helium plasma jet was investigated using two different shielding gases, namely carbon dioxide and nitrogen. Electrical, optical, and chemical characteristics were analyzed to study the start-up behavior. Using a comprehensive set of diagnostic tools, including frequency and averaged power measurements, patient leakage current and temperature measurements, optical emission spectroscopy, Fourier transform infrared spectroscopy, and liquid assays, a temporal analysis of 90 min of plasma operation was performed. By combining and comparing the results, a start-up behavior was determined and its importance highlighted. Furthermore, the dominant reaction pathway of the investigated liquid species, including the role of the different shielding gases, was deduced.