arXiv subjects

Paul Huslage

Publications and source records attributed to Paul Huslage.

5 recordsLinked to original sources

arXiv2026

Stochastic single-stage stellarator optimization using fixed-boundary equilibria

In this paper, single-stage stellarator optimization is combined with stochastic coil optimization to improve the robustness of the stellarator as compared to deterministic methods. The plasma boundary, solved with an MHD solver in fixed-boundary mode, is linked to a set of randomly perturbed coils via the squared flux. The optimizer avoids sharp local minima and can reach improved configurations. Two different configurations obtained with our method, one quasi-axisymmetric and one quasi-helically symmetric, are compared against both the standard stochastic stage II method and the single-stage method. The new configurations shown here yield improved squared flux, quasisymmetry, and particle loss following a posteriori perturbation of the coils.

physics.plasm-ph↗

arXiv2026

Designing A Buildable Optimized Stellarator to Confine Electron-Positron Plasmas

In this paper, the design of the the plasma equilibrium and superconducting coils for the Electrons and Positrons in an Optimized Stellarator EPOS experiment is presented. With newly developed stellarator optimization tools, including single-stage and stochastic optimization, as well as HTS strain, this work demonstrates that it is possible to achieve key metrics for the buildability and confinement properties of the device. In particular, satisfactory quality of quasisymmetry and stellarator robustness is designed, and engineering requirements are met for eight different candidates. A feasibility study is presented that optimizes multiple candidates for different plasma major radii and coil currents, as well as the best EPOS candidate to date.

physics.plasm-ph↗

arXiv2025

Manufacturing Tolerances of Non-Planar Coils for an Optimized Tabletop Stellarator

Stellarator coils are known for their complexity and departure from planarity, along with tight manufacturing tolerances in order to achieve the target magnetic field accuracy. These requirements can lead to increased costs and delays in assembly; failure to meet them can compromise the stellarator's performance. Small-scale experiments offer opportunities to develop and benchmark stellarator coil design and evaluation methods more quickly and at lower budget. In this work, we analyze precise 3D scans of the manufacturing deviations of two 3D-printed coil frames (steel, Ti alloy) and one CNC-machined coil frame (Al alloy), as part of assessing these approaches to fabricating high-temperature superconducting (HTS) coils for a tabletop stellarator. The deviations are measured along the coil length, then modeled using Gaussian processes to extract characteristic length scales. Finally a statistical study of field accuracy is performed using relevant experimental parameters. We conclude that the manufacturing perturbations along the winding path from CNC-machining are almost an order of magnitude lower than those from Additive Manufacturing. Together with high overall fabrication accuracy, this allows for higher magnetic field precision and an improved assembly process.

physics.ins-det↗

arXiv2025

A Non-planar ReBCO Test Coil with 3D-printed Aluminum Support Structure for the EPOS Stellarator

We report on the test of a small scale, non-planar coil using non-insulated ReBCO tape wound on a 3D-printed aluminum support structure. A 3D-scan of the winding frame which was printed out of AlSi10Mg using selective laser melting, showed peak manufacturing deviations of 0.3 mm. We tested the coil with 21 turns of 3 mm wide tape cooled both by liquid nitrogen and with a cryocooler. We achieved a central field strength of up to 21 mT which agrees with the prediction suggesting that we manufactured the coil without defects. The peak field was reached at a supply current of 120 A. The current leads showed a contact resistance of $\left(2.25\pm0.13\right)μΩ$. The discharge time $L/R$ was found to be 0.63 s in liquid nitrogen and 2.92 s when cooled by the cryocooler. From this we estimate a winding pack temperature of 41 K.

physics.ins-det↗

arXiv2024

Strain Optimization for ReBCO High-Temperature Superconducting Stellarator Coils in SIMSOPT

This work provides an optimization mechanism to ensure the compatibility of ReBCO (Rare-earth Barium Copper Oxide) high-temperature superconducting (HTS) tapes with non-planar stellarator coils. ReBCO coils enable higher field strengths and operating temperatures for the magnet systems of future fusion reactors but are sensitive to strain due to their brittle, ceramic functional layer. We have implemented a metric to optimize strain on stellarator coils made from ReBCO superconductors into the stellarator optimization framework \texttt{SIMSOPT} and used it to design new stellarator coil configurations. To ensure structural integrity of coils wound with HTS tape, we introduce a penalty on binormal curvature and torsion along a coil. It can be used to optimize the orientation of the winding path for a given coil filament or to jointly optimize orientation and coil filament. We apply the strain optimization to three cases. For the EPOS (Electrons and Positrons in an Optimized Stellarator) design, we combine the strain penalty with an objective for quasisymmetry into a single-stage optimization; this enables us to find a configuration with excellent quasisymmetry at the smallest possible size compatible with the use of ReBCO tape. For CSX (Columbia Stellarator eXperiment), in addition to HTS strain, we add a penalty to prevent net tape rotation to ease the coil winding process. If the strain is calculated for a coil at reactor scale, we find a considerable variation of the binormal and torsional strain over the cross section of the large winding pack (0.5\,m x 0.5\,m). By exploiting the overall orientation of the winding pack as a degree of freedom, we can reduce binormal and torsional strains below limits for every ReBCO stack.

physics.plasm-ph↗