Dataset to accompany publication: Helium metastable density determination in the COST reference source by absolutely calibrated optical emission spectroscopy

This dataset includes the spectra that accompany the manuscript "Helium metastable density determination in the COST reference source by absolutely calibrated optical emission spectroscopy", available at https://doi.org/10.1063/5.0218352. The spectra can be used to reproduce figures 4, 5, 7, 8, and 9 in the main text with the appropriate collisional-radiative model and absolute calibration. The data supporting the collisional-radiative model is derived from open sources such as the EEDF program and LxCat and can be provided upon request to the corresponding author. The spectra in this dataset were collected with an ESA 4000 echelle spectrometer and are contained in two zip files corresponding to the admixture and power sweep as detailed in the manuscript. The spectra themselves are in .spa files where the first column is the wavelength and the second the intensity. The .spa files can be opened directly in MATLAB. 

The abstract for the accepted manuscript is as follows: 

Helium metastable densities in the COST Reference Microplasma Jet are estimated for a variety of He/N2 admixtures and dissipated powers by applying a collisional-radiative model to absolutely calibrated optical emission spectroscopy measurements. This is accomplished by delineating the excitation mechanisms that result in the N2(C–B) and N2+(B–X) emission bands, the latter of which is strongly coupled to the presence of helium metastables. A number of other plasma parameters are established and discussed for each operating condition including the electron energy distribution function, reduced electric field, rate constants, and electron density. With these parameters, the reaction rates for the primary ionization pathways are also calculated, emphasizing the importance of helium metastables for discharge sustainment. Good agreement with existing literature is found for most plasma parameters and for helium metastable densities in particular. A clear [N2]−1 relationship between the nitrogen concentration and density of helium metastables is demonstrated, as has been identified in previous studies in analogous atmospheric pressure plasma jets. This validates the efficacy of this optical technique for determining helium metastable densities and establishes it as a viable, and in many cases, more accessible alternative to other means of quantifying helium metastables in low-temperature plasmas.