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Adjoint methods for quasi-symmetry of vacuum fields on a surface

Published online by Cambridge University Press:  21 January 2022

Richard Nies Open the ORCID record for Richard Nies [Opens in a new window] ,
Elizabeth J. Paul Open the ORCID record for Elizabeth J. Paul [Opens in a new window] ,
Stuart R. Hudson  and
Amitava Bhattacharjee
Richard Nies*
Affiliation:
Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08543, USA Princeton Plasma Physics Laboratory, Princeton, NJ 08540, USA
Elizabeth J. Paul
Affiliation:
Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08543, USA Princeton Plasma Physics Laboratory, Princeton, NJ 08540, USA
Stuart R. Hudson
Affiliation:
Princeton Plasma Physics Laboratory, Princeton, NJ 08540, USA
Amitava Bhattacharjee
Affiliation:
Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08543, USA Princeton Plasma Physics Laboratory, Princeton, NJ 08540, USA
*
†Email address for correspondence: rnies@pppl.gov
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Abstract

Adjoint methods can speed up stellarator optimisation by providing gradient information more efficiently compared with finite-difference evaluations. Adjoint methods are herein applied to vacuum magnetic fields, with objective functions targeting quasi-symmetry and a rotational transform value on a surface. To measure quasi-symmetry, a novel way of evaluating approximate flux coordinates on a single flux surface without the assumption of a neighbourhood of flux surfaces is proposed. The shape gradients obtained from the adjoint formalism are evaluated numerically and verified against finite-difference evaluations.

Keywords

fusion plasmaplasma devicesplasma confinement
Type
Research Article
Information
Journal of Plasma Physics , Volume 88 , Issue 1 , February 2022 , 905880106
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Copyright
Copyright © The Author(s), 2022. Published by Cambridge University Press

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References

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