Contains the source data used for the publication "Combination of optical emission spectroscopy and multivariate data analysis techniques as a versatile non-invasive tool for characterizing xenon/krypton mixed gas plasma inside operating ion thrusters" including all Langmuir probe and spectra measurements as well as calibration measurements for gas flow controllers and spectrometer. The evaluated data can be seen in the "Source data_Xe-Kr-plasma-OES.xlsx".