SPECTROSCOPIC CHARACTERIZATION OF THE DIII-D DIVERTOR

Radiative losses along a fixed view into the divertor chamber of the D III-D tokamak [Plasma Physics Controlled Nuclear Fusion Research 1986 (International Atomic Energy Agency, Vienna, 1987), Vol I, p. 159] hav e been characterized for attached and partially detached discharges by analyzing line-integrated vacuum ultraviolet (VUV) signals, Essential ly all the emission can be ascribed to carbon and deuterium. Because t he majority of the most intense lines, which lie at wavelengths above 1100 Angstrom, are not accessible to the present instrumentation, exte nsive use has been made of collisional-radiative (CR) calculations for level populations of the important ions in order to relate the total radiated power to shorter wavelength transitions. In beam-heated plasm as? the fraction of radiation detected from carbon along the VUV spect rometer view is usually between 50% and 80% of the total. Carbon densi ties are estimated from a simplified approach to modelling the emissio n using a one-dimensional transport code. For partially detached plasm as the concentrations range from 2%-6% of the electron density; but in attached plasmas it appears that carbon may supply most of the electr ons in the divertor region just below the X point. Ion temperatures ar e measured from Doppler broadening of spectral lines by fitting measur ed profiles to theoretical lineshapes, which account precisely for ato mic sublevel splitting caused by the Zeeman/Paschen-Back effect in the tokamak magnetic field. (C) 1997 American Institute of Physics.