Spatially resolved spectroscopic ion temperature measurements at plasma edge of the T-10 tokamak.

Spectroscopic diagnostics of the edge ion temperature were developed on the T-10 tokamak. Spatially resolved measurements of C5+ and other ionization states of carbon spectral line shapes are provided. Spectra were measured with high spectral resolution using 14 lines of sight in one poloidal section of the tokamak. Each measured line-integrated spectrum contains a combination of multiple local spectra with corresponding values of ion temperature. Modeling of spatial distribution of line emissivity and spectral line shapes along the lines of sight allows the reconstruction of the ion temperature profile on the basis of the closest match of measured and modeled spectra. The fine structure of spectral line, Zeeman effect, and apparatus function are taken into account during data processing. Obtained ion temperature profiles, Ti(r), at the plasma edge are in good agreement with ion temperature profiles measured by Charge eXchange Recombination Spectroscopy (CXRS) diagnostics of T-10. Use of the CXRS equipment for measurements of passive spectra can provide additional information on the temporal evolution of the edge ion temperature. Developed diagnostics provide necessary data for the research of geodesic acoustic modes, which are strongly dependent on plasma edge ion temperature.

Charge exchange recombination spectroscopy on the T-10 tokamak.

The charge exchange recombination spectroscopy (CXRS) diagnostics on the T-10 tokamak is described. The system is based on a diagnostic neutral beam and includes three high etendue spectrometers designed for the ITER edge CXRS system. A combined two-channel spectrometer is developed for simultaneous measurements of two beam-induced spectral lines using the same lines of sight. A basic element of the combined spectrometer is a transmitting holographic grating designed for the narrow spectral region 5291 ± 100 Å. The whole CXRS system provides simultaneous measurements of two CXRS impurity spectra and Hα beam line. Ion temperature measurements are routinely provided using the C(6+) CXRS spectral line 5291 Å. Simultaneous measurements of carbon densities and one more impurity (oxygen, helium, lithium etc.) are carried out. Two light collecting systems with 9 lines of sight in each system are used in the diagnostics. Spatial resolution is up to 2.5 cm and temporal resolution of 1 ms is defined by the diagnostic neutral beam diameter and pulse duration, respectively. Experimental results are shown to demonstrate a wide range of the CXRS diagnostic capabilities on T-10 for investigation of impurity transport processes in tokamak plasma. Developed diagnostics provides necessary experimental data for studying of plasma electric fields, heat and particle transport processes, and for investigation of geodesic acoustic modes.