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Title: Two-dimensional magnetohydrodynamic simulations of poloidal flows in tokamaks and MHD pedestal

Abstract

Poloidal rotation is routinely observed in present-day tokamak experiments, in particular near the plasma edge and in the high-confinement mode of operation. According to the magnetohydrodynamic (MHD) equilibrium theory [R. Betti and J. P. Freidberg, Phys. Plasmas 7, 2439 (2000)], radial discontinuities form when the poloidal velocity exceeds the poloidal sound speed (or rather, more correctly, the poloidal magneto-slow speed). Two-dimensional compressible magnetohydrodynamic simulations show that the transonic discontinuities develop on a time scale of a plasma poloidal revolution to form an edge density pedestal and a localized velocity shear layer at the pedestal location. While such an MHD pedestal surrounds the entire core, the outboard side of the pedestal is driven by the transonic discontinuity while the inboard side is caused by a poloidal redistribution of the mass. The MHD simulations use a smooth momentum source to drive the poloidal flow. Soon after the flow exceeds the poloidal sound speed, the density pedestal and the velocity shear layer form and persist into a quasi steady state. These results may be relevant to the L-H transition, the early stages of the pedestal and edge transport barrier formation.

Authors:
 [1];  [1];  [2]
  1. Department of Mechanical Engineering, University of Rochester, Rochester, New York 14627 (United States)
  2. (United States)
Publication Date:
OSTI Identifier:
22043502
Resource Type:
Journal Article
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 18; Journal Issue: 9; Other Information: (c) 2011 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1070-664X
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; BOUNDARY LAYERS; CONFINEMENT; DENSITY; MAGNETOHYDRODYNAMICS; MASS; MHD EQUILIBRIUM; PLASMA; PLASMA DENSITY; PLASMA SIMULATION; SOUND WAVES; STEADY-STATE CONDITIONS; TOKAMAK DEVICES

Citation Formats

Guazzotto, L., Betti, R., and Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540. Two-dimensional magnetohydrodynamic simulations of poloidal flows in tokamaks and MHD pedestal. United States: N. p., 2011. Web. doi:10.1063/1.3640809.
Guazzotto, L., Betti, R., & Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540. Two-dimensional magnetohydrodynamic simulations of poloidal flows in tokamaks and MHD pedestal. United States. doi:10.1063/1.3640809.
Guazzotto, L., Betti, R., and Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540. Thu . "Two-dimensional magnetohydrodynamic simulations of poloidal flows in tokamaks and MHD pedestal". United States. doi:10.1063/1.3640809.
@article{osti_22043502,
title = {Two-dimensional magnetohydrodynamic simulations of poloidal flows in tokamaks and MHD pedestal},
author = {Guazzotto, L. and Betti, R. and Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540},
abstractNote = {Poloidal rotation is routinely observed in present-day tokamak experiments, in particular near the plasma edge and in the high-confinement mode of operation. According to the magnetohydrodynamic (MHD) equilibrium theory [R. Betti and J. P. Freidberg, Phys. Plasmas 7, 2439 (2000)], radial discontinuities form when the poloidal velocity exceeds the poloidal sound speed (or rather, more correctly, the poloidal magneto-slow speed). Two-dimensional compressible magnetohydrodynamic simulations show that the transonic discontinuities develop on a time scale of a plasma poloidal revolution to form an edge density pedestal and a localized velocity shear layer at the pedestal location. While such an MHD pedestal surrounds the entire core, the outboard side of the pedestal is driven by the transonic discontinuity while the inboard side is caused by a poloidal redistribution of the mass. The MHD simulations use a smooth momentum source to drive the poloidal flow. Soon after the flow exceeds the poloidal sound speed, the density pedestal and the velocity shear layer form and persist into a quasi steady state. These results may be relevant to the L-H transition, the early stages of the pedestal and edge transport barrier formation.},
doi = {10.1063/1.3640809},
journal = {Physics of Plasmas},
issn = {1070-664X},
number = 9,
volume = 18,
place = {United States},
year = {2011},
month = {9}
}