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A comparison of turbulent transport in a quasi-helical and a quasi-axisymmetric stellarator

Part of: Focus on Fusion

Published online by Cambridge University Press:  19 September 2019

I. J. McKinney Open the ORCID record for I. J. McKinney [Opens in a new window] ,
M. J. Pueschel ,
B. J. Faber Open the ORCID record for B. J. Faber [Opens in a new window] ,
C. C. Hegna ,
J. N. Talmadge ,
D. T. Anderson ,
H. E. Mynick  and
P. Xanthopoulos
I. J. McKinney*
Affiliation:
Department of Engineering Physics, University of Wisconsin-Madison, Madison, WI 53706, USA
M. J. Pueschel
Affiliation:
Institute for Fusion Studies, University of Texas at Austin, Austin, TX 78712, USA
B. J. Faber
Affiliation:
Department of Engineering Physics, University of Wisconsin-Madison, Madison, WI 53706, USA
C. C. Hegna
Affiliation:
Department of Engineering Physics, University of Wisconsin-Madison, Madison, WI 53706, USA
J. N. Talmadge
Affiliation:
Department of Electrical & Computer Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA
D. T. Anderson
Affiliation:
Department of Electrical & Computer Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA
H. E. Mynick
Affiliation:
Princeton Plasma Physics Laboratory, Princeton, NJ 08543, USA
P. Xanthopoulos
Affiliation:
Max-Planck-Institut für Plasmaphysik, Wendelsteinstraße 1, 17491 Greifswald, Germany
*
†Email address for correspondence: imckinney@wisc.edu
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Abstract

Ion-temperature-gradient-driven (ITG) turbulence is compared for two quasi-symmetric (QS) stellarator configurations to determine the relationship between linear growth rates and nonlinear heat fluxes. We focus on the quasi-helically symmetric (QHS) stellarator HSX and the quasi-axisymmetric (QAS) stellarator NCSX. In normalized units, HSX exhibits higher growth rates than NCSX, while heat fluxes in gyro-Bohm units are lower in HSX. These results hold for simulations made with both adiabatic and kinetic electrons. The results show that HSX has a larger number of subdominant modes than NCSX and that eigenmodes are more spatially extended in HSX. We conclude that the consideration of nonlinear physics is necessary to accurately assess the heat flux due to ITG turbulence when comparing QS stellarator equilibria.

Keywords

fusion plasmaplasma instabilitiesplasma nonlinear phenomena
Type
Research Article
Information
Journal of Plasma Physics , Volume 85 , Issue 5 , October 2019 , 905850503
Copyright
© Cambridge University Press 2019 

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