Hostname: page-component-cd9895bd7-gvvz8 Total loading time: 0 Render date: 2024-12-24T15:53:56.820Z Has data issue: false hasContentIssue false
  • English
  • Français

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]
Get access Rights & Permissions [Opens in a new window]

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 

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Cohen, R. H. & Ryutov, D. D. 1995 Plasma sheath in a tilted magnetic field: closing of the diamagnetic currents; effect on plasma convection. Phys. Plasmas 2 (6).Google Scholar
Dejarnac, R., Stangeby, P. C., Goldston, R. J., Gauthier, E., Horacek, J., Hron, M., Kocan, M., Komm, M., Panek, R., Pitts, R. A. et al. 2015 Understanding narrow SOL power flux component in COMPASS limiter plasmas by use of Langmuir probes. J. Nucl. Mater. 463, 381–384.CrossRefGoogle Scholar
Halpern, F. D., Labombard, B., Terry, J. L. & Zweben, S. J. 2017 Outer midplane scrape-off layer profiles and turbulence in simulations of Alcator C-Mod inner-wall limited discharges. Phys. Plasmas 24.Google Scholar
Halpern, F. D. & Ricci, P. 2017 Velocity shear, turbulent saturation, and steep plasma gradients in the scrape-off layer of inner-wall limited tokamaks. Nucl. Fusion 57, 034001.Google Scholar
Halpern, F. D., Ricci, P., Jolliet, S., Loizu, J., Morales, J., Mosetto, A., Musil, F., Riva, F., Tran, T. M. & Wersal, C. 2016 The GBS code for tokamak scrape-off layer simulations. J. Comput. Phys. 315, 388–408.Google Scholar
Hidalgo, C., Gonc, B., Silva, C., Pedrosa, M. A., Erents, K., Hron, M. & Matthews, G. F. 2003 Experimental investigation of dynamical coupling between turbulent transport and parallel flows in the JET plasma-boundary region. Phys. Rev. Lett. 91 (6).CrossRefGoogle ScholarPubMed
Kocan, M., Pitts, R. A., Arnoux, G., Balboa, I., de Vries, P. C., Dejarnac, R., Furno, I., Goldston, R. J., Gribov, Y., Horacek, J. et al. 2015 Impact of a narrow limiter SOL heat flux channel on the ITER first wall panel shaping. Nucl. Fusion 55, 033019.Google Scholar
Loizu, J., Ricci, P., Halpern, F. D. & Jolliet, S. 2012 Boundary conditions for plasma fluid models at the magnetic presheath entrance. Phys. Plasmas 19 (12).Google Scholar
Loizu, J., Ricci, P., Halpern, F. D., Jolliet, S. & Mosetto, A. 2013 On the electrostatic potential in the scrape-off layer of magnetic confinement devices. Plasma Phys. Control. Fusion 55 (12), 124019.Google Scholar
Loizu, J., Ricci, P., Halpern, F. D., Jolliet, S. & Mosetto, A. 2014 Effect of the limiter position on the scrape-off layer width, radial electric field and intrinsic flows. Nucl. Fusion 54 (8), 083033.Google Scholar
Mosetto, A., Halpern, F. D., Jolliet, S., Loizu, J. & Ricci, P. 2013 Turbulent regimes in the tokamak scrape-off layer. Phys. Plasmas 20 (9).CrossRefGoogle Scholar
Mosetto, A., Halpern, F. D., Jolliet, S., Loizu, J. & Ricci, P. 2015 Finite ion temperature effects on scrape-off layer turbulence. Phys. Plasmas 22 (1).CrossRefGoogle Scholar
Motojima, O. 2015 The ITER project construction status. Nucl. Fusion 55, 104023.Google Scholar
Nespoli, F., Furno, I., Halpern, F. D., Labit, B., Loizu, J., Ricci, P. & Riva, F. 2016 Non-linear simulations of the TCV scrape-off layer. Nucl. Mater. Energy 0, 1–4.Google Scholar
Nespoli, F., Labit, B., Furno, I., Horacek, J., Tsui, C. K., Boedo, J. A., Maurizio, R., Reimerdes, H., Theiler, C., Ricci, P. et al. , The Eurofusion MST Team & The TCV Team 2017 Understanding and suppressing the near scrape-off layer heat flux feature in inboard-limited plasmas in TCV. Nucl. Fusion 57, 126029.Google Scholar
Ramos, J. J. 2005 General expression of the gyroviscous force. Phys. Plasmas 12.CrossRefGoogle Scholar
Ricci, P., Halpern, F. D., Jolliet, S., Loizu, J., Mosetto, A., Fasoli, A., Furno, I. & Theiler, C. 2012 Simulation of plasma turbulence in scrape-off layer conditions: the GBS code, simulation results and code validation. Plasma Phys. Control. Fusion 54 (12), 124047.Google Scholar
Ricci, P. & Rogers, B. N. 2013 Plasma turbulence in the scrape-off layer of tokamak devices. Phys. Plasmas 20.Google Scholar
Stangeby, P. C. 2000 The Plasma Boundary of Magnetic Fusion Devices. IOP Publishing.CrossRefGoogle Scholar
Strawitch, C. M. & Emmert, G. A. 1981 Non-ambipolar transport in a magnetic divertor. Nucl. Fusion 21.Google Scholar
Tsui, C. K., Boedo, J. A., Halpern, F. D., Loizu, J., Nespoli, F., Horacek, J., Labit, B., Morales, J., Reimerdes, H., Theiler, C. et al. 2017 Poloidal asymmetry in the narrow heat flux feature in the TCV scrape-off layer. Phys. Plasmas 24.Google Scholar
Tsui, H. Y. W. 1992 Formation of a velocity shear layer in confined plasmas: formation of a velocity shear layer in confined plasmas. Phys. Plasmas 4.Google Scholar
Zeiler, A., Drake, J. F. & Rogers, B. 1997 Nonlinear reduced Braginskii equations with ion thermal dynamics in toroidal plasma. Phys. Plasmas 4.Google Scholar
Zhu, B., Francisquez, M. & Rogers, B. N. 2017 Global 3D two-fluid simulations of the tokamak edge region: turbulence, transport, profile evolution, and spontaneous ExB rotation. Phys. Plasmas 24.Google Scholar
Zweben, S. J., Boedo, J. A., Grulke, O., Hidalgo, C., LaBombard, B., Maqueda, R. J., Scarin, P. & Terry, J. L. 2007 Edge turbulence measurements in toroidal fusion devices. Plasma Phys. Control. Fusion 49.Google Scholar
Zweben, S. J., Davis, W. M., Kaye, S. M., Myra, J. R., Bell, R. E., Leblanc, B. P., Maqueda, R. J., Munsat, T., Sabbagh, S. A., Sechrest, Y. et al. & NSTX 2015 Edge and SOL turbulence and blob variations over a large database in NSTX. Nucl. Fusion 55.CrossRefGoogle Scholar