Efficient calculation of self magnetic field, self-force, and self-inductance for electromagnetic coils with rectangular cross-section

For designing high-field electromagnets, the Lorentz force on coils needs to be computed in order to design suitable support structures, and the inductance should be computed to evaluate the stored energy and dynamics. Also, the magnetic field and its variation inside the conductor is of interest fo...

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Main Authors: Matt Landreman, Siena Hurwitz, Thomas M. Antonsen
Format: Article
Language:English
Published: IOP Publishing 2025-01-01
Series:Nuclear Fusion
Subjects:
Online Access:https://doi.org/10.1088/1741-4326/adb04e
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author Matt Landreman
Siena Hurwitz
Thomas M. Antonsen
author_facet Matt Landreman
Siena Hurwitz
Thomas M. Antonsen
author_sort Matt Landreman
collection DOAJ
description For designing high-field electromagnets, the Lorentz force on coils needs to be computed in order to design suitable support structures, and the inductance should be computed to evaluate the stored energy and dynamics. Also, the magnetic field and its variation inside the conductor is of interest for computing stress and strain, and due to superconducting quench limits. For these force, inductance, energy, and internal field calculations, the coils cannot be naively approximated as infinitesimally thin filaments due to divergences when the source and evaluation points coincide, so more computationally demanding calculations are usually required, resolving the finite cross-section of the conductors. Here, we present a new alternative method that enables the internal magnetic field vector, self-force, and self-inductance to be computed rapidly and accurately within a 1D filament model. The method is applicable to coils for which the curve center-line can have general noncircular shape, as long as the conductor width is small compared to the radius of curvature. This paper extends a previous calculation for circular-cross-section conductors (Hurwitz et al 2024 IEEE Trans. Magn. ) to consider the case of rectangular cross-section. The reduced model is derived by rigorous analysis of the singularity, regularizing the filament integrals such that they match the true high-dimensional integrals at high coil aspect ratio. The new filament model exactly recovers analytic results for a circular coil, and is shown to accurately reproduce full finite-cross-section calculations for a non-planar coil of a stellarator magnetic fusion device. Due to the efficiency of the model here, it is well suited for use inside design optimization.
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spelling doaj-art-256fad7f2a064a30a8529db61efdc7942025-02-10T09:06:59ZengIOP PublishingNuclear Fusion0029-55152025-01-0165303600810.1088/1741-4326/adb04eEfficient calculation of self magnetic field, self-force, and self-inductance for electromagnetic coils with rectangular cross-sectionMatt Landreman0https://orcid.org/0000-0002-7233-577XSiena Hurwitz1https://orcid.org/0000-0001-6659-9659Thomas M. Antonsen2Institute for Research in Electronics and Applied Physics , University of Maryland, College Park, MD 20740, United States of AmericaInstitute for Research in Electronics and Applied Physics , University of Maryland, College Park, MD 20740, United States of AmericaInstitute for Research in Electronics and Applied Physics , University of Maryland, College Park, MD 20740, United States of AmericaFor designing high-field electromagnets, the Lorentz force on coils needs to be computed in order to design suitable support structures, and the inductance should be computed to evaluate the stored energy and dynamics. Also, the magnetic field and its variation inside the conductor is of interest for computing stress and strain, and due to superconducting quench limits. For these force, inductance, energy, and internal field calculations, the coils cannot be naively approximated as infinitesimally thin filaments due to divergences when the source and evaluation points coincide, so more computationally demanding calculations are usually required, resolving the finite cross-section of the conductors. Here, we present a new alternative method that enables the internal magnetic field vector, self-force, and self-inductance to be computed rapidly and accurately within a 1D filament model. The method is applicable to coils for which the curve center-line can have general noncircular shape, as long as the conductor width is small compared to the radius of curvature. This paper extends a previous calculation for circular-cross-section conductors (Hurwitz et al 2024 IEEE Trans. Magn. ) to consider the case of rectangular cross-section. The reduced model is derived by rigorous analysis of the singularity, regularizing the filament integrals such that they match the true high-dimensional integrals at high coil aspect ratio. The new filament model exactly recovers analytic results for a circular coil, and is shown to accurately reproduce full finite-cross-section calculations for a non-planar coil of a stellarator magnetic fusion device. Due to the efficiency of the model here, it is well suited for use inside design optimization.https://doi.org/10.1088/1741-4326/adb04eelectromagnetic coilself-inductancemagnetic energyself-forceLorentz forcestellarator
spellingShingle Matt Landreman
Siena Hurwitz
Thomas M. Antonsen
Efficient calculation of self magnetic field, self-force, and self-inductance for electromagnetic coils with rectangular cross-section
Nuclear Fusion
electromagnetic coil
self-inductance
magnetic energy
self-force
Lorentz force
stellarator
title Efficient calculation of self magnetic field, self-force, and self-inductance for electromagnetic coils with rectangular cross-section
title_full Efficient calculation of self magnetic field, self-force, and self-inductance for electromagnetic coils with rectangular cross-section
title_fullStr Efficient calculation of self magnetic field, self-force, and self-inductance for electromagnetic coils with rectangular cross-section
title_full_unstemmed Efficient calculation of self magnetic field, self-force, and self-inductance for electromagnetic coils with rectangular cross-section
title_short Efficient calculation of self magnetic field, self-force, and self-inductance for electromagnetic coils with rectangular cross-section
title_sort efficient calculation of self magnetic field self force and self inductance for electromagnetic coils with rectangular cross section
topic electromagnetic coil
self-inductance
magnetic energy
self-force
Lorentz force
stellarator
url https://doi.org/10.1088/1741-4326/adb04e
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AT sienahurwitz efficientcalculationofselfmagneticfieldselfforceandselfinductanceforelectromagneticcoilswithrectangularcrosssection
AT thomasmantonsen efficientcalculationofselfmagneticfieldselfforceandselfinductanceforelectromagneticcoilswithrectangularcrosssection