Fig. 4From: Non-invasive assessment of plasma parameters inside an ion thruster combining optical emission spectroscopy and principal component analysisThe measured spectral range from 820 nm to 841 nm exhibits six xenon transitions, which are shown in the energy level scheme for neutral xenon generated from the data from Ref. [41]. A corresponding example spectrum is shown in the inset. The strongest transitions feeding the upper levels of the observed transitions are also shown. The relaxation times of the transitions are given according to Ref. [43]. Using the labeling given in the figure, the transitions can be found in Table 1 for additional detailsBack to article page