US-12620498-B2 - Planar coil stellarator

Abstract

Disclosed herein is a stellarator comprising two sets of coils, namely a set of encircling coils which encircle the plasma axis, and a set of shaping coils which do not encircle any other coil or the plasma. In some embodiments, the encircling coils include a structural element to maintain their shape under magnetic forces. In some embodiments, the shaping coils are mounted onto one or more structural elements which, together with the shaping coils, constitute a field shaping unit. Also disclosed is a controller which may modify the electrical current flowing in one or more subsets of the coils in order to achieve target plasma parameters. Also disclosed is a method of designing a set of shaping coils by discretizing a surface dipole or current potential distribution.

Inventors

• David Gates
• CAOXIANG ZHU
• Kenneth Hammond

Assignees

• THE TRUSTEES OF PRINCETON UNIVERSITY

Dates

Publication Date

20260505

Application Date

20231223

Claims (6)

1. 1 . A method for designing a stellarator including one or more planar coils and an array of encircling coils, comprising: (a) obtaining for the stellarator (i) a target plasma, and (ii) a configuration of the array of encircling coils; (b) using a surface current or a surface current potential, determining a continuous surface dipole distribution that produces one or more magnetic fields for confining the target plasma (c) receiving one or more parameters selected from a resolution of the surface to be discretized into coils, a cutoff current, and/or a maximum coil linear dimension; and (b) based on the received one or more parameters, defining a configuration of the one or more planar coils by discretizing the determined continuous surface dipole distribution.
2. 2 . The method of claim 1 , further comprising generating a model of the plasma confined by the configuration of the one or more planar coils and the array of encircling coils.
3. 3 . The method of claim 2 , wherein the generating of the model of the plasma comprises using a free-boundary plasma solver.
4. 4 . The method of claim 1 , further comprising optimizing the target plasma by iteratively defining the configuration of the one or more planar coils.
5. 5 . The method of claim 1 , further comprising defining forces on the one or more planar coils.
6. 6 . The method of claim 5 , further comprising designing mechanical supports to react to the forces on the one or more planar coils.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS The present disclosure is a continuation of U.S. patent application Ser. No. 18/119,981 filed on Mar. 10, 2023, which application claims the benefit of the filing date of U.S. Provisional Patent Application No. 63/319,580 filed on Mar. 14, 2022, the disclosures of which are hereby incorporated by reference herein in their entireties. STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH This invention was made with government support under Grant Nos. DE-AC02-09CH11466 awarded by the Department of Energy and DE-AR0001264 awarded by the Department of Energy/Advanced Research Projects Agency (ARPA-E). The government has certain rights in the invention. FIELD OF THE DISCLOSURE The present disclosure is directed to stellarators and, in particular, stellarators incorporating one or more planar coils. The stellarators incorporating the one or more planar coils are adapted to confine a plasma, such as to confine a plasma within a void defined by one or more field shaping units. BACKGROUND OF THE DISCLOSURE Fusion is a process which can be harnessed to release the nuclear energy in abundant fuels, without emissions of greenhouse gases and with significantly lower and shorter-lived radioactive waste than conventional fission nuclear reactors. Fusion fuels fuse only at extremely high temperature, at which all materials are in the plasma state. Magnetic fusion devices aim to confine a fusing plasma using magnetic fields. The two leading magnetic fusion approaches are the tokamak and the stellarator, both of which utilize a magnetic field which has the topology of a torus. Stellarators have the advantage over tokamaks of operating in steady state and requiring no additional electrical current to be driven within the plasma itself. Prior stellarator designs have included non-planar electromagnetic coils which have a complex, 3D curvature. These electromagnetic coils are difficult to design, fabricate, integrate, and maintain. Some stellarator designs include electromagnetic coils which link other electromagnetic coils, akin to the links of a chain. These electromagnetic coils cannot be fabricated separately and then assembled; they must be fabricated together, which further increases the difficulty of their fabrication, integration, and maintenance. One example of a stellarator employing complex electromagnetic coils is the Large Helical Device (LHD) experiment operated by the Japanese National Institute for Fusion Science (Yoshimura, Y., et al. 2005. Journal of Physics: Conference Series 25 (1): 189). These electromagnetic coils are helical coils, which are non-planar and interlock the plasma and the other helical coils. These electromagnetic coils must be wound with electrical wire on-site. Stellarators employing such electromagnetic coils are termed Torsatrons or Heliotrons. Another example of a stellarator employing complex electromagnetic coils is the Wendelstein 7-X (W7-X) experiment operated by the German Max Planck Institute for Plasma Physics (Beidler, Craig, et al. 1990. Fusion Technology 17 (1): 148-68). With reference to FIG. 1A, W7-X uses a combination of external planar coils 101 and modular coils 102. The external planar coils are planar 101, interlock the plasma, and do not interlock any other coils. The modular coils 102 are non-planar, interlock the plasma, and do not interlock any other coils. Stellarators employing this kind of coils can be termed Heliases or, more generally, modular coil stellarators. The National Compact Stellarator Experiment (NCSX) was a proposed experiment that was canceled during its construction. A few different designs were proposed (Neilson, G H, et al. 2000. In Proceedings of the 42nd Annual Meeting of the APS Division of Plasma Physics Québec City, Canada). A proposed “saddle coil design” which utilized (i) Toroidal Field (TF) coils, which are planar coils that interlock the plasma, but which do not interlock any other coils; and (ii) saddle coils, which are non-planar coils that do not interlock the plasma, but do not interlock any other coils. An alternative design, referred to as the “optimized background coils and conformal coils design” utilized (i) background coils which are planar, interlock the plasma, and that interlock other background coils; and (ii) saddle coils, which are planar, do not interlock the plasma, and which do not interlock any other coils. Several experimental designs, such as W7-X and NCSX, incorporate planar trim coils (Rummel, Thomas, et al. 2012. IEEE Transactions on Applied Superconductivity 22 (3): 4201704-4201704). Planar trim coils are planar, do not interlock the plasma, and do not interlock with any other coils. Planar trim coils are part of a control system rather than a magnetic field generation system. As such, their purpose is to correct a magnetic field which is off nominal in some way (e.g., due to some imprecision in construction or due to plasma behavior). At the nominal operating point, planar tr