Fig. 1. Schematic for the principle of the charge exchange recombination (left). Right, CXRS spectrum; Doppler shift (ΔλD), width (ΔλFWHM), and intensity of the spectral line give information on the rotation velocity, temperature, and density of the observed species. Remainder, reference wavelength of CVI (n=8→7) is 529.05 nm.

Fig. 2. Top view of the filter spectrometer optical layout. Designed center wavelength for the three filters (Channel 3) is 529.55 nm, the tilt angle of the silica filter for the two short wavelength (529.05 and 528.55 nm; Channels 2 and 1, respectively) is about 3.6° and 5.1°, respectively.

Fig. 3. Schematic representation of the measurement principle of filter spectroscopy. Three Gaussian functions with different central wavelength and width are used to represent the spectral sensitivity and a slight difference for each channel is assumed.

Fig. 4. Ion temperature and rotation velocity dependence of the line intensity ratios RL and RR as calculated with Eq. (4).