Greedy permanent magnet optimization

Journal Article · 02 February 2023 · Nuclear Fusion

DOI: https://doi.org/10.1088/1741-4326/acb4a9 · OSTI ID:1923414

Kaptanoglu, Alan A. ; Conlin, Rory ; Landreman, Matt

Abstract A number of scientific fields rely on placing permanent magnets in order to produce a desired magnetic field. We have shown in recent work that the placement process can be formulated as sparse regression. However, binary, grid-aligned solutions are desired for realistic engineering designs. We now show that the binary permanent magnet problem can be formulated as a quadratic program with quadratic equality constraints, the binary, grid-aligned problem is equivalent to the quadratic knapsack problem with multiple knapsack constraints, and the single-orientation-only problem is equivalent to the unconstrained quadratic binary problem. We then provide a set of simple greedy algorithms for solving variants of permanent magnet optimization, and demonstrate their capabilities by designing magnets for stellarator plasmas. The algorithms can a-priori produce sparse, grid-aligned, binary solutions. Despite its simple design and greedy nature, we provide an algorithm that compares with or even outperforms the state-of-the-art algorithms while being substantially faster, more flexible, and easier to use.

• Research Organization: Princeton Univ., NJ (United States); Univ. of California, Oakland, CA (United States); Univ. of Maryland, College Park, MD (United States)
• Sponsoring Organization: USDOE; USDOE Office of Science (SC)
• Grant/Contract Number: AC02-05CH11231; FG02-93ER54197; SC0022005
• OSTI ID: 1923414
• Journal Information: Nuclear Fusion, Journal Name: Nuclear Fusion Journal Issue: 3 Vol. 63; ISSN 0029-5515
• Publisher: IOP PublishingCopyright Statement
• Country of Publication: IAEA
• Language: English