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Title: Multispecies density peaking in gyrokinetic turbulence simulations of low collisionality Alcator C-Mod plasmas

Peaked density profiles in low-collisionality AUG and JET H-mode plasmas are probably caused by a turbulently driven particle pinch, and Alcator C-Mod experiments confirmed that collisionality is a critical parameter. Density peaking in reactors could produce a number of important effects, some beneficial, such as enhanced fusion power and transport of fuel ions from the edge to the core, while others are undesirable, such as lower beta limits, reduced radiation from the plasma edge, and consequently higher divertor heat loads. Fundamental understanding of the pinch will enable planning to optimize these impacts. We show that density peaking is predicted by nonlinear gyrokinetic turbulence simulations based on measured profile data from low collisionality H-mode plasma in Alcator C-Mod. Multiple ion species are included to determine whether hydrogenic density peaking has an isotope dependence or is influenced by typical levels of low-Z impurities, and whether impurity density peaking depends on the species. We find that the deuterium density profile is slightly more peaked than that of hydrogen, and that experimentally relevant levels of boron have no appreciable effect on hydrogenic density peaking. The ratio of density at r/a = 0.44 to that at r/a = 0.74 is 1.2 for the majority D and minority H ionsmore » (and for electrons), and increases with impurity Z: 1.1 for helium, 1.15 for boron, 1.3 for neon, 1.4 for argon, and 1.5 for molybdenum. The ion temperature profile is varied to match better the predicted heat flux with the experimental transport analysis, but the resulting factor of two change in heat transport has only a weak effect on the predicted density peaking.« less
Authors:
; ; ;  [1] ; ; ; ;  [2] ;  [2] ;  [3] ;  [2] ;  [4] ;  [2] ;  [5] ; ;  [6]
  1. Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543 (United States)
  2. MIT Plasma Science and Fusion Center, 175 Albany St., Cambridge, Massachusetts 02139 (United States)
  3. (United Kingdom)
  4. (United States)
  5. (France)
  6. General Atomics, P.O. Box 85608, San Diego, California 92186-5608 (United States)
Publication Date:
OSTI Identifier:
22410435
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 22; Journal Issue: 6; 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; ARGON; BORON; DEUTERIUM; DEUTERIUM IONS; DIVERTORS; EDGE LOCALIZED MODES; ELECTRONS; HEAT FLUX; HEAT TRANSFER; HEATING LOAD; HELIUM; H-MODE PLASMA CONFINEMENT; HYDROGEN IONS; JET TOKAMAK; MOLYBDENUM; NEON; PINCH EFFECT; PLASMA IMPURITIES; TURBULENCE