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Title: Gyrokinetic particle simulation of neoclassical transport in the pedestal/scrape-off region of a tokamak plasma

Abstract

A gyrokinetic neoclassical solution for a diverted tokamak edge plasma has been obtained for the first time using the massively parallel Jaguar XT3 computer at Oak Ridge National Laboratory. The solutions show similar characteristics to the experimental observations: electric potential is positive in the scrape-off layer and negative in the H-mode layer, and the parallel rotation is positive in the scrape-off layer and at the inside boundary of the H-mode layer. However, the solution also makes a new physical discovery that there is a strong ExB convective flow in the scrape-off plasma. A general introduction to the edge simulation problem is also presented.

Authors:
 [1];  [2];  [3];  [4];  [1];  [5];  [2];  [6];  [7];  [8];  [9]
  1. Columbia University
  2. New York University
  3. California Institute of Technology, University of California, Davis
  4. Hinton Associates
  5. ORNL
  6. Princeton Plasma Physics Laboratory (PPPL)
  7. University of California, Irvine
  8. University of Colorado, Boulder
  9. SciDAC Prototype FSP Center for Plasma Edge Simulation
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
931867
DOE Contract Number:
DE-AC05-00OR22725
Resource Type:
Conference
Resource Relation:
Conference: SciDAC 2006, Denver, CO, USA, 20060625, 20060629
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; TOKAMAK DEVICES; PLASMA SCRAPE-OFF LAYER; NEOCLASSICAL TRANSPORT THEORY; H-MODE PLASMA CONFINEMENT; COMPUTERIZED SIMULATION; EDGE LOCALIZED MODES

Citation Formats

Adams, Mark, Chang, C. S., Cummings, J., Hinton, F., Keyes, David E, Klasky, Scott A, Ku, S., Lee, W. W., Lin, Z., Parker, Scott, and CPES Team, the. Gyrokinetic particle simulation of neoclassical transport in the pedestal/scrape-off region of a tokamak plasma. United States: N. p., 2006. Web.
Adams, Mark, Chang, C. S., Cummings, J., Hinton, F., Keyes, David E, Klasky, Scott A, Ku, S., Lee, W. W., Lin, Z., Parker, Scott, & CPES Team, the. Gyrokinetic particle simulation of neoclassical transport in the pedestal/scrape-off region of a tokamak plasma. United States.
Adams, Mark, Chang, C. S., Cummings, J., Hinton, F., Keyes, David E, Klasky, Scott A, Ku, S., Lee, W. W., Lin, Z., Parker, Scott, and CPES Team, the. Sun . "Gyrokinetic particle simulation of neoclassical transport in the pedestal/scrape-off region of a tokamak plasma". United States. doi:.
@article{osti_931867,
title = {Gyrokinetic particle simulation of neoclassical transport in the pedestal/scrape-off region of a tokamak plasma},
author = {Adams, Mark and Chang, C. S. and Cummings, J. and Hinton, F. and Keyes, David E and Klasky, Scott A and Ku, S. and Lee, W. W. and Lin, Z. and Parker, Scott and CPES Team, the},
abstractNote = {A gyrokinetic neoclassical solution for a diverted tokamak edge plasma has been obtained for the first time using the massively parallel Jaguar XT3 computer at Oak Ridge National Laboratory. The solutions show similar characteristics to the experimental observations: electric potential is positive in the scrape-off layer and negative in the H-mode layer, and the parallel rotation is positive in the scrape-off layer and at the inside boundary of the H-mode layer. However, the solution also makes a new physical discovery that there is a strong ExB convective flow in the scrape-off plasma. A general introduction to the edge simulation problem is also presented.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2006},
month = {Sun Jan 01 00:00:00 EST 2006}
}

Conference:
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  • An integrated gyrokinetic particle simulation with turbulence and neoclassical physics in a diverted tokamak edge plasma has been performed. Neoclassical equilibrium gyrokinetic solutions in the whole edge plasma have been separated from the turbulence activities for the first time, using the massively parallel Jaguar XT3 computer at Oak Ridge National Laboratory. The equilibrium solutions in an H-mode-like edge plasma condition show strongly sheared global ExB and parallel flows in the entire edge plasma including the pedestal and scrape-off regions. In an L-mode-like edge plasma condition, the sheared flows in the pedestal layer are much weaker, supporting the conjecture that themore » neoclassical flow-shear may play a significant role in the H-mode physics.« less
  • Two dimensional calculations of impurtiy transport in a high recycling divertor scrape-off region have been made with an updated version of the ZTRANS Monte Carlo computer code. The calculations use plasma parameters for the Doublet 3 divertor, as computed by the Planet Fluid Transport Code. The effects of electric field, particle drift velocities, and thermal forces are included in the calculations. For all impurity species studied, it is found that impurity transport is dominated by frictional forces, over most of the scrape-off region. Light impurities, however, impinge substantially closer to the divertor plate center than do heavy impurities, which tendmore » to impinge at the outer plate boundary. 8 refs., 4 figs., 2 tabs.« less
  • No abstract prepared.
  • No abstract prepared.
  • Energy and particle transport rates are decoupled in the H-mode edge since the ion thermal transport rate is primarily set by the neoclassical transport of the deuterium ions in the tail of the thermal energy distribution, while the net particle transport rate is set by anomalous transport of the colder bulk ions. Ion orbit loss drives the energy distributions away from Maxwellian, and describes the anisotropy, poloidal asymmetry and local minimum near the separatrix observed in the Ti profile. Non-Maxwellian distributions also drive large intrinsic edge flows, and the interaction of turbulence at the top of the pedestal with themore » intrinsic edge flow can generate an intrinsic core torque. The primary driver of the radial electric field (Er) in the pedestal and scrapeoff layer (SOL) are kinetic neoclassical effects, such as ion orbit loss of tail ions and parallel electron loss to the divertor. This paper describes the first multi-species kinetic neoclassical transport calculations for ELM-free H-mode pedestal and scrape-off layer on DIII-D using XGC0, a 5D full-f particle-in-cell drift-kinetic solver with self-consistent neutral recycling and sheath potentials. Quantitative agreement between the flux-driven simulation and the experimental electron density, impurity density and orthogonal measurements of impurity temperature and flow profiles is achieved by adding random-walk particle diffusion to the guiding-center drift motion. This interpretative technique quantifies the role of neoclassical, anomalous and neutral transport to the overall pedestal structure, and consequently illustrates the importance of including kinetic effects self-consistently in transport calculations around transport barriers.« less