skip to main content

Title: Kinetic modeling of divertor heat load fluxes in the Alcator C-Mod and DIII-D tokamaks

The guiding-center kinetic neoclassical transport code, XGC0 [Chang et al., Phys. Plasmas 11, 2649 (2004)], is used to compute the heat fluxes and the heat-load width in the outer divertor plates of Alcator C-Mod and DIII-D tokamaks. The dependence of the width of heat-load fluxes on neoclassical effects, neutral collisions, and anomalous transport is investigated using the XGC0 code. The XGC0 code includes realistic X-point geometry, a neutral source model, the effects of collisions, and a diffusion model for anomalous transport. It is observed that the width of the XGC0 neoclassical heat-load is approximately inversely proportional to the total plasma current I{sub p.} The scaling of the width of the divertor heat-load with plasma current is examined for an Alcator C-Mod discharge and four DIII-D discharges. The scaling of the divertor heat-load width with plasma current is found to be weaker in the Alcator C-Mod discharge compared to scaling found in the DIII-D discharges. The effect of neutral collisions on the 1/I{sub p} scaling of heat-load width is shown not to be significant. Although inclusion of poloidally uniform anomalous transport results in a deviation from the 1/I{sub p} scaling, the inclusion of the anomalous transport that is driven by ballooning-typemore » instabilities results in recovering the neoclassical 1/I{sub p} scaling. The Bohm or gyro-Bohm scalings of anomalous transport do not strongly affect the dependence of the heat-load width on plasma current. The inclusion of anomalous transport, in general, results in widening the width of neoclassical divertor heat-load and enhances the neoclassical heat-load fluxes on the divertor plates. Understanding heat transport in the tokamak scrape-off layer plasmas is important for strengthening the basis for predicting divertor conditions in ITER.« less
Authors:
 [1] ; ;  [2] ;  [3] ; ;  [4] ; ; ; ;  [5] ;  [6]
  1. Tech-X Corporation, Boulder, Colorado 80303 (United States)
  2. Department of Physics, Lehigh University, Bethlehem, Pennsylvania 18015 (United States)
  3. National Fusion Research Institute, Daejeon, 305-333 (Korea, Republic of)
  4. Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540 (United States)
  5. MIT Plasma Science and Fusion Center, Cambridge, Massachusetts 02139 (United States)
  6. General Atomics, San Diego, California 92121 (United States)
Publication Date:
OSTI Identifier:
22490167
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 22; Journal Issue: 9; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ALCATOR DEVICE; BALLOONING INSTABILITY; BASES; COLLISIONS; DIFFUSION; DIVERTORS; DOUBLET-3 DEVICE; ELECTRIC CURRENTS; HEAT FLUX; HEAT TRANSFER; HEATING LOAD; ITER TOKAMAK; KINETIC EQUATIONS; NEOCLASSICAL TRANSPORT THEORY; PLASMA; PLASMA SCRAPE-OFF LAYER