Scaling of Divertor Heat Flux Profile Widths in DIII-D
The width of the divertor heat flux profile w{sub q,div} is of great interest in future large tokamaks as well as many present devices. Previous studies examining the parametric dependence of w{sub q,div} have arrived at diverse scalings in JET, ASDEX-Upgrade, JT60-U, DIII-D, and NSTX with results somewhat at variance with each other. We attempt here to perform a new series of experiments in DIII-D under controlled conditions to obtain scaling of the divertor heat flux peak value, profile width, and divertor plate power as a function of plasma input parameters, with the maximum number of divertor and scrape-off-layer (SOL) diagnostics brought to bear. We performed measurements in lower single-null edge localized mode (ELM) H-mode diverted configurations that were not strongly pumped due to the strike-point positions. We varied the plasma current I{sub p} at constant toroidal field (B{sub T}) and line-averaged density {bar n}{sub e} at constant I{sub p} and B{sub T}. The neutral beam injected power P{sub inj} was changed at constant I{sub p} and BT, B{sub T} at constant I{sub p}, and B{sub T}/I{sub p} at constant q{sub 95}. The divertor heat flux was calculated from infrared camera measurements using a new high-resolution fast-framing IR camera. The IR camera recorded divertor plate surface thermal emission at many-kilohertz frame rates through the whole discharge, so that time-averaged data as well as rapid changes due to ELMs were obtained. The heat flux at each position in the radial profile was calculated at each of the times steps using the THEODOR 2D heat flux analysis code. We show scaling of the divertor peak heat flux and profile width as a function of the parameters varied, and compare with published results from other devices.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 966573
- Report Number(s):
- LLNL-PROC-413814; TRN: US0904064
- Resource Relation:
- Journal Volume: 415; Journal Issue: 1; Conference: Presented at: 36th EPS Conference on Plasma Physics, Sofia, Bulgaria, Jun 29 - Jul 03, 2009
- Country of Publication:
- United States
- Language:
- English
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