Recorded spectra between 9892 and 9895 cm^-1. From top to bottom: discharge operated at MW power of 25, 50, and 100 W. The blue line is the fit composed of a superposition of Gauss profiles to the peaks exceeding the minimum peak intensity threshold (dashed horizontal line). A green square indicates an identified N I line, while a gray circle marks an unidentified line. See main text for more information (Sect. 3.8). Note that the ordinate axis is not the same scale for each plot.