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Turbulent impurity transport simulations in Wendelstein 7-X plasmas

Part of: Invited Contributions from the 18th European Fusion Theory Conference Focus on Fusion

Published online by Cambridge University Press:  02 February 2021

J. M. García-Regaña Open the ORCID record for J. M. García-Regaña [Opens in a new window] ,
M. Barnes Open the ORCID record for M. Barnes [Opens in a new window] ,
I. Calvo Open the ORCID record for I. Calvo [Opens in a new window] ,
F. I. Parra Open the ORCID record for F. I. Parra [Opens in a new window] ,
J. A. Alcusón Open the ORCID record for J. A. Alcusón [Opens in a new window] ,
R. Davies Open the ORCID record for R. Davies [Opens in a new window] ,
A. González-Jerez Open the ORCID record for A. González-Jerez [Opens in a new window] ,
A. Mollén Open the ORCID record for A. Mollén [Opens in a new window] ,
E. Sánchez Open the ORCID record for E. Sánchez [Opens in a new window]  and
J. L. Velasco Open the ORCID record for J. L. Velasco [Opens in a new window]
...Show all authors
J. M. García-Regaña*
Affiliation:
Laboratorio Nacional de Fusión, CIEMAT, Av. Complutense, 28040, Spain
M. Barnes
Affiliation:
Rudolf Peierls Centre for Theoretical Physics, University of Oxford, OxfordOX1 3PU, UK
I. Calvo
Affiliation:
Laboratorio Nacional de Fusión, CIEMAT, Av. Complutense, 28040, Spain
F. I. Parra
Affiliation:
Rudolf Peierls Centre for Theoretical Physics, University of Oxford, OxfordOX1 3PU, UK
J. A. Alcusón
Affiliation:
Max-Planck Institut für Plasmaphysik, Wendelsteinstrasse 1, 17491, Germany
R. Davies
Affiliation:
York Plasma Institute, Department of Physics, University of York, Heslington, YorkYO10 5DD, UK
A. González-Jerez
Affiliation:
Laboratorio Nacional de Fusión, CIEMAT, Av. Complutense, 28040, Spain
A. Mollén
Affiliation:
Princeton Plasma Physics Laboratory, Princeton, NJ08543-0451, USA
E. Sánchez
Affiliation:
Laboratorio Nacional de Fusión, CIEMAT, Av. Complutense, 28040, Spain
J. L. Velasco
Affiliation:
Laboratorio Nacional de Fusión, CIEMAT, Av. Complutense, 28040, Spain
A. Zocco
Affiliation:
Max-Planck Institut für Plasmaphysik, Wendelsteinstrasse 1, 17491, Germany
*
†Email address for correspondence: jose.regana@ciemat.es
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Abstract

A study of turbulent impurity transport by means of quasilinear and nonlinear gyrokinetic simulations is presented for Wendelstein 7-X (W7-X). The calculations have been carried out with the recently developed gyrokinetic code stella. Different impurity species are considered in the presence of various types of background instabilities: ion temperature gradient (ITG), trapped electron mode (TEM) and electron temperature gradient (ETG) modes for the quasilinear part of the work; ITG and TEM for the nonlinear results. While the quasilinear approach allows one to draw qualitative conclusions about the sign or relative importance of the various contributions to the flux, the nonlinear simulations quantitatively determine the size of the turbulent flux and check the extent to which the quasilinear conclusions hold. Although the bulk of the nonlinear simulations are performed at trace impurity concentration, nonlinear simulations are also carried out at realistic effective charge values, in order to know to what degree the conclusions based on the simulations performed for trace impurities can be extrapolated to realistic impurity concentrations. The presented results conclude that the turbulent radial impurity transport in W7-X is mainly dominated by ordinary diffusion, which is close to that measured during the recent W7-X experimental campaigns. It is also confirmed that thermodiffusion adds a weak inward flux contribution and that, in the absence of impurity temperature and density gradients, ITG- and TEM-driven turbulence push the impurities inwards and outwards, respectively.

Keywords

plasma simulationfusion plasmaplasma confinement
Type
Research Article
Information
Journal of Plasma Physics , Volume 87 , Issue 1 , February 2021 , 855870103
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Copyright
Copyright © The Author(s), 2021. Published by Cambridge University Press

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References

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