Calibration of coherence imaging spectroscopy using spectral line sources

Abstract

Coherence imaging spectroscopy (CIS) measures the two-dimensional profiles of both ion temperature and ion velocity in plasmas. The interferometric technique is realized by a certain relation between a phase and a wavelength of light emerging from the birefringent crystal. The calibration for the CIS system requires monochromatic and tunable light sources near He II line (468.6 nm) or C III line (465 nm) where the CIS measures. In this research, the CIS system has been upgraded by implementing an electron multiplier CCD (EM-CCD) and a CIS cell. A monochromator validates the linearity of the phase relation on the wavelength near the He II line. As an in-situ calibration at Ring Trap 1 (RT-1) plasma device, two spectral lines of Ti and Zn lamps obtain the accurate dispersion function of phase. It is found that the simple method with two spectral lines is reliable and sufficient for the calibration.