Fast charge exchange spectroscopy using a Fabry-Perot spectrometer in the JIPP TII-U tokamak

A new charge exchange spectroscopic technique using a Fabry-Port spectrometer has been developed to increase the photon flux at the detector, and to improve the time resolution of ion temperature and plasma rotation velocity measurements. The spectral resolution is obtained by arranging two-dimensional fiber-optics and a two-dimensional detector at the focal plane of a coupled lens located on both sides of a Fabry-Perot spectrometer. The effective finesse (the ratio of the spectral resolution to the free spectral range) of the Fabry-Perot interferometer in this system is 14. The time evolution of the ion temperature is obtained with a time resolution of 125 gs and with a spatial resolution of 3 cm (eight channels).