Abstract
We have obtained the first measurements of ne and Te 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 H-mode, and radiative divertor operation with puffing of D2 and impurities. Mapping of the data to either the (Lpol, φ) or (R, Z) planes with the EFIT equilibrium is used to analyze the 2D profiles. We find that in ELMing H-mode: ne, Te, and Pe are relatively constant along field lines from the X-point to the divertor plate, especially near the separatrix field line. With D2 puffing, the DTS profiles indicate that Te in a large part of divertor region below the X-point is dramatically reduced from ~ 30-40 eV in ELMing H-mode to 1-2 eV. This results in a fairly uniform low-Te divertor, with an increased electron density in the range of 2 to 4 × 1020 m-3. Detailed comparisons of the spatial profiles of ne, Te, and electron pressure Pe, are presented for several operating modes. In addition, these data are compared with initial calculations from the UEDGE fluid code.
Original language | English |
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Pages (from-to) | 595-601 |
Number of pages | 7 |
Journal | Journal of Nuclear Materials |
Volume | 241-243 |
DOIs | |
State | Published - Feb 11 1997 |
Funding
This work has been a team effort, including engineering, technical, and computations support in addition to the Physics analysis. Work supported by U.S. Department of Energy under Contract DE-AC03-89ER5114 (GA), W-7405-ENG-48 (LLNL) and DE-AC05-96OR22464 (ORNL).
Keywords
- Detached plasma
- DIII-D
- Divertor plasma
- Plasma temperature diagnostic
- Poloidal divertor