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EPJ Techniques and Instrumentation
Fig. 8 | EPJ Techniques and Instrumentation

Fig. 8

From: Non-invasive assessment of plasma parameters inside an ion thruster combining optical emission spectroscopy and principal component analysis

Fig. 8

PCA scores of the time-resolved optical emission measurements for a xenon plasma driven with 1.2 MHz RF excitation (a). The defined region that is mapped by the scores of the cw optical emission spectra from which the correlation has been established is shown in red. Scores of time-resolved spectra outside this region cannot reliably be used to estimate plasma parameters as they lie outside the area where the one-to-one correlation was established and fitted. Plasma parameters extracted from the fitting in this range are uncertain. The oscillation of the PCA scores as a function of delay time is shown in (b) for a series of time-resolved spectra. Mass flow, RF input power and average electron temperature and density are given in the plot. PC1 and PC2 oscillate with twice the radio frequency as the corresponding line intensities in Fig. 7

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