High-resolution spectroscopy of the D i i i–D divertor region

Abstract

The results of spectral measurements in the D iii–D divertor region, carried out using a high-resolution spectrometer and a survey spectrograph developed at the TRINITI Laboratory, Russia are presented in this report. Observations were made along a vertical chord passing through the X point and intersecting the divertor floor at the major radius of the V1 ports. The high-resolution spectrometer is designed for simultaneous measurements along eight spatial chords with a time resolution of 7 ms. Each of the eight spectra is dispersed over 512 pixels on an intensified charge coupled device (CCD) detector. 768 frames of data are recorded directly to RAM memory of a PC computer during every discharge. High optical throughput is achieved simultaneously with high spectral resolution; the instrument has an f/number of 3 and a spectral resolution of 0.025 nm. The spectrometer can also operate in survey mode, recording a spectral region of 13 nm with 0.1-nm resolution. Using Doppler broadening of spectral lines, the temperature of deuterium atoms and of C ii and C iii was obtained for L, H, and ELMing H-mode regimes in D iii–D. Using the survey spectrograph, photographic exposures of divertor plasma radiation were obtained spanning the spectral ranges 340–424 and 486–848 nm, in second and first orders of the grating, respectively. The spectrograph is stigmatic and has an f/number of 3.