Numerical modeling of diffusive heat transport across magnetic islands and highly stochastic layers
- Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, 85748 Garching (Germany)
Diffusive heat transport across magnetic islands and highly stochastic layers is studied numerically for realistic values of {chi}{sub parallel}/{chi}{sub perpendicular} in cylindrical geometry, where {chi}{sub parallel} denotes the heat diffusion coefficient parallel and {chi}{sub perpendicular} the one perpendicular to the magnetic field lines. The computations are performed with a second-order finite difference scheme, for which the numerical errors are independent from the value of {chi}{sub parallel}/{chi}{sub perpendicular} [S. Guenter et al., J. Comput. Phys. 209, 354 (2005)]. Sufficient spatial resolution is ensured by using an unsheared helical coordinate system. The heat flux around magnetic islands as well as the effective radial heat diffusivity {chi}{sub r} are examined and compared to analytical theory. The temperature perturbations caused by magnetic islands and the resulting bootstrap current perturbations essential for the stability of neoclassical tearing modes are analyzed and compared to analytical predictions [R. Fitzpatrick, Phys. Plasmas 2, 825 (1995)]. Agreement is found in the 'small' and 'large' island limits, but an enhanced NTM drive is observed in between. A correction factor that can reproduce the numerical results very well is presented. For a highly stochastic layer, produced by five strongly overlapping islands, the radial heat diffusivity {chi}{sub r} is determined and compared to several analytical theories.
- OSTI ID:
- 20974982
- Journal Information:
- Physics of Plasmas, Vol. 14, Issue 5; Other Information: DOI: 10.1063/1.2722980; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 1070-664X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
BOOTSTRAP CURRENT
COMPUTERIZED SIMULATION
CORRECTIONS
CYLINDRICAL CONFIGURATION
ELECTRON TEMPERATURE
ERRORS
FINITE DIFFERENCE METHOD
GEOMETRY
HEAT FLUX
HEAT TRANSFER
ION TEMPERATURE
LAYERS
MAGNETIC FIELDS
MAGNETIC ISLANDS
MAGNETOHYDRODYNAMICS
NEOCLASSICAL TRANSPORT THEORY
PLASMA
SPATIAL RESOLUTION
TEARING INSTABILITY