Stellarator coil optimization supporting multiple magnetic configurations

Journal Article · 24 November 2022 · Nuclear Fusion

DOI: https://doi.org/10.1088/1741-4326/aca10d · OSTI ID:1899780

Lee, Brandon F. ; Paul, Elizabeth J. ; Stadler, Georg ; Landreman, Matt

Abstract We present a technique that can be used to design stellarators with a high degree of experimental flexibility. For our purposes, flexibility is defined by the range of values the rotational transform can take on the magnetic axis of the vacuum field while maintaining satisfactory quasisymmetry. We show that accounting for configuration flexibility during the modular coil design improves flexibility beyond that attained by previous methods. Careful placement of planar control coils and the incorporation of an integrability objective enhance the quasisymmetry and nested flux surface volume of each configuration. We show that it is possible to achieve flexibility, quasisymmetry, and nested flux surface volume to reasonable degrees with a relatively simple coil set through an NCSX-like example. This example coil design is optimized to achieve three rotational transform targets and nested flux surface volumes in each magnetic configuration larger than the NCSX design plasma volume. Our work suggests that there is a tradeoff between flexibility, quasisymmetry, and volume of nested flux surfaces.

• Research Organization: Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)
• Sponsoring Organization: Simons Foundation; USDOE
• Grant/Contract Number: AC02-09CH11466
• OSTI ID: 1899780
• Journal Information: Nuclear Fusion, Journal Name: Nuclear Fusion Journal Issue: 1 Vol. 63; ISSN 0029-5515
• Publisher: IOP PublishingCopyright Statement
• Country of Publication: IAEA
• Language: English