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Title: Nonlinear magnetohydrodynamic simulation of Tore Supra hollow current profile discharges

Abstract

Magnetohydrodynamic (MHD) activity often undermines the realization of fully noninductive plasma discharges in the Tore Supra tokamak [J. Jacquinot, Nucl. Fusion 45, S118 (2005)], by producing large degradation of electron energy confinement in the plasma core and the bifurcation to a regime with permanent MHD activity. The nonlinear evolution of MHD modes in these hollow current density profile discharges is studied with the full-scale three-dimensional MHD code XTOR [K. Lerbinger and J.-F. Luciani, J. Comput. Phys. 97, 444 (1991)] and compared with experimental features. Large confinement degradation is predicted when q(0) is close to 2. This derives either from the full reconnection of an unstable double-tearing mode, or from the coupling between a single tearing mode and adjacent stable modes in a region with reduced magnetic shear.

Authors:
; ; ; ; ;  [1];  [2]
  1. Association Euratom-CEA, CEA/DSM/DRFC, Centre de Cadarache, 13108 Saint Paul lez Durance (France)
  2. (France)
Publication Date:
OSTI Identifier:
20974990
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 14; Journal Issue: 5; Other Information: DOI: 10.1063/1.2733677; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; BIFURCATION; CURRENT DENSITY; CURRENTS; ELECTRONS; MAGNETIC RECONNECTION; MAGNETOHYDRODYNAMICS; NONLINEAR PROBLEMS; PLASMA; PLASMA CONFINEMENT; PLASMA SIMULATION; TEARING INSTABILITY; THREE-DIMENSIONAL CALCULATIONS; TORE SUPRA TOKAMAK

Citation Formats

Maget, P., Huysmans, G. T. A., Garbet, X., Ottaviani, M., Luetjens, H., Luciani, J.-F., and Centre de Physique Theorique, Ecole Polytechnique, F-91128 Palaiseau. Nonlinear magnetohydrodynamic simulation of Tore Supra hollow current profile discharges. United States: N. p., 2007. Web. doi:10.1063/1.2733677.
Maget, P., Huysmans, G. T. A., Garbet, X., Ottaviani, M., Luetjens, H., Luciani, J.-F., & Centre de Physique Theorique, Ecole Polytechnique, F-91128 Palaiseau. Nonlinear magnetohydrodynamic simulation of Tore Supra hollow current profile discharges. United States. doi:10.1063/1.2733677.
Maget, P., Huysmans, G. T. A., Garbet, X., Ottaviani, M., Luetjens, H., Luciani, J.-F., and Centre de Physique Theorique, Ecole Polytechnique, F-91128 Palaiseau. Tue . "Nonlinear magnetohydrodynamic simulation of Tore Supra hollow current profile discharges". United States. doi:10.1063/1.2733677.
@article{osti_20974990,
title = {Nonlinear magnetohydrodynamic simulation of Tore Supra hollow current profile discharges},
author = {Maget, P. and Huysmans, G. T. A. and Garbet, X. and Ottaviani, M. and Luetjens, H. and Luciani, J.-F. and Centre de Physique Theorique, Ecole Polytechnique, F-91128 Palaiseau},
abstractNote = {Magnetohydrodynamic (MHD) activity often undermines the realization of fully noninductive plasma discharges in the Tore Supra tokamak [J. Jacquinot, Nucl. Fusion 45, S118 (2005)], by producing large degradation of electron energy confinement in the plasma core and the bifurcation to a regime with permanent MHD activity. The nonlinear evolution of MHD modes in these hollow current density profile discharges is studied with the full-scale three-dimensional MHD code XTOR [K. Lerbinger and J.-F. Luciani, J. Comput. Phys. 97, 444 (1991)] and compared with experimental features. Large confinement degradation is predicted when q(0) is close to 2. This derives either from the full reconnection of an unstable double-tearing mode, or from the coupling between a single tearing mode and adjacent stable modes in a region with reduced magnetic shear.},
doi = {10.1063/1.2733677},
journal = {Physics of Plasmas},
number = 5,
volume = 14,
place = {United States},
year = {Tue May 15 00:00:00 EDT 2007},
month = {Tue May 15 00:00:00 EDT 2007}
}
  • Current drive and current profile control constitute one of the major lines of investigations on the 1.7 MA supra-conducting Tokamak Tore Supra. Sixty seconds fully non-inductive pulses were obtained in 1994 by means of Lower Hybrid current drive. A successful fast wave current drive programme is also ongoing. It is shown that D{sub 0} beams of 500{endash}1000 keV, at a power level of 3{endash}5 MW, would complete these physics investigations on the route of fully non-inductive advanced Tokamak scenarios. The current drive efficiency, the fast ion losses and the shine-through are calculated by means of a Fokker Planck code andmore » a Monte-Carlo code. The angle of injection and beam energy otimization calculations are presented. The results of the 2 codes are compared. {copyright} {ital 1996 American Institute of Physics.}« less
  • The link between the current profile and the confinement is studied, involving various regimes: high power minority ion cyclotron resonant heating, high power lower hybrid current drive, fast wave direct electron heating and current drive and pellet enhanced performance. It is shown that the electron heat diffusivity decreases when the magnetic shear increases in the confinement zone and/or when it decreases in the plasma center. {copyright} {ital 1995 American Institute of Physics.}
  • In view of high-power, long pulse steady-state operation, Tore Supra has incorporated in its design the active control of heat and particles in a realistic environment. A new inner-wall technology was developed in 1994 and is to be tested in 1995-1996 with a totally rebuilt 40-deg toroidal sector. A carbon-fiber-reinforced carbon-metal compound is based on the newest brazing technology and regorous quality control. Components such as the toroidal pump limiter and the guard limiters of plasma-heating antennas are being developed in the same way. For structures where brazing is difficult, boron carbide-coated components have been developed and installed in Toremore » Supra. For lower heat fluxes, a bolted concept has been designed and tested. The influence of inner-first-wall misalignment in Tore Supra on the power exhaust limitation of brazed components has been studied. Results from the technological development for the different power exhaust systems and the associated experimental knowledge obtained during plasma operation in Tore Supra are presented. 63 refs., 34 figs., 2 tabs.« less
  • Recent results of ion cyclotron minority heating have been obtained with an improved L-mode confinement, close to ELMy H-mode prediction, at relatively high density. The confinement exceeds the standard L-mode by a factor up to 1.7. The improvement of the confinement is observed in both electron and ion channels with reduction of heat diffusivities. This improved confinement regime presents some features similar to the results previously observed in many tokamaks: ALCATOR C-MOD [1] with ICRH, and radiation improved confinement (RI) mode with neutral beam injection in TEXTOR [2], TFTR [3], DIII-D [4]. (c) 1999 American Institute of Physics.
  • The physical erosion of the Tokamak inside walls can have an important incidence on the dust particulate production. Sputtering discharges are proposed to have highlight on the dust growth mechanisms from carbon atom or clusters injected in plasmas. Their condensation give rise to solid particulate precursors which nature depends strongly on the plasma parameters. A comparison between the carbon structure of dust particles produced in sputtering discharges and of a dust sample collected in the Tore Supra Tokamak is proposed, the sputtering process being the dominant wall erosion in the present mode of operation of this fusion device. The structuralmore » differences are discussed and can be correlated to specific plasma situations.« less