First measurements of electron temperature and density with divertor Thomson scattering in radiative divertor discharges on DIII-D

We have obtained the first measurements of n(e) and T-e in the DIII-D divertor region with a multi-pulse (20 Hz) divertor Thomson scattering (DTS) system. Eight measurement locations are distributed vertically up to 21 cm above the divertor plate. Two-dimensional distributions have been obtained by sweeping the divertor plasma across the DTS measurement location. Several operating modes have been studied, including Ohmic, L-mode, ELMing K-mode, and radiative divertor operation with puffing of D-2 and impurities. Mapping of the data to either the (L-pol, phi) or (R, Z) planes with the EFIT equilibrium is used to analyze the 2D profiles. We find that in ELMing H-mode: n(e), T-e, and P-e are relatively constant along field lines from the X-point to the divertor plate, especially near the separahix field line. With D, puffing, the DTS profiles indicate that T-e in a large part of divertor region below the X-point is dramatically reduced from similar to 30-40 eV in ELMing H-mode to 1-2 eV. This results in a fairly uniform low-T-e divertor, with an increased electron density in the range of 2 to 4 x 10(20) m(-3). Detailed comparisons of the spatial profiles of n(e), T-e, and electron pressure P-e, are presented for several operating modes. In addition, these data are compared with initial calculations from the UEDGE fluid code.