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Scrape-off-layer current loops and floating potential in limited tokamak plasmas

Part of: Focus on Fusion

Published online by Cambridge University Press:  04 December 2017

J. Loizu ,
J. A. Morales ,
F. D. Halpern ,
P. Ricci  and
P. Paruta
J. Loizu*
Affiliation:
Max-Planck-Institut für Plasmaphysik, D-17491 Greifswald, Germany
J. A. Morales
Affiliation:
Commissariat à l’Energie Atomique IRFM, F-13108 Saint Paul Lez Durance, France
F. D. Halpern
Affiliation:
General Atomics, PO Box 85608, San Diego, CA 92186-5608, USA
P. Ricci
Affiliation:
Swiss Plasma Center, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
P. Paruta
Affiliation:
Swiss Plasma Center, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
*
†Email address for correspondence: [email protected]
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Abstract

We investigate the question of how plasma currents circulate and close in the scrape-off-layer (SOL) of convection-limited tokamak plasmas. A simplified two-fluid model describes how currents must evacuate charge at the sheaths due to cross-field currents that are not divergence-free. These include turbulence-driven polarization currents and poloidally asymmetric equilibrium diamagnetic currents. The theory provides an estimate for the radial profile of the floating potential, which reveals a dipolar structure like the one observed experimentally. Simulations with a fluid turbulence code provide evidence for the predicted behaviour of currents and floating potential.

Keywords

fusion plasmaplasma flowsplasma sheaths
Type
Research Article
Information
Journal of Plasma Physics , Volume 83 , Issue 6 , December 2017 , 575830601
Copyright
© Cambridge University Press 2017 

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