摘要
Abstract
To address the challenge of precise control over complex three-dimensional magnetic field configurations in stel-larator magnetic confinement fusion devices and overcome technical bottlenecks of conventional coil magnet systems in spa-tial arrangement and operational maintenance,this study systematically investigated finite element numerical simulation methods and additive manufacturing technology schemes for complex curved surface permanent magnets.The REGCOIL_PM current potential optimization method was employed to obtain the three-dimensional geometry of stellarator permanent magnet structures,which achieved an optimized balance between plasma surface magnetic field accuracy and per-manent magnet complexity based on the Tikhonov regularization strategy.Considering the geometric characteristics of per-manent magnets featuring spatially twisted trajectories and continuously varying cross-sections,a MATLAB-based auto-matic STL mesh generation program was developed to achieve precise digital characterization of complex geometries.A three-dimensional magnetostatic finite element model was established in COMSOL,where the continuous spatial variation of magnetization intensity and direction was configured through interpolation function techniques.Three-dimensional simu-lation analysis conducted on the NCSX-configuration stellarator demonstrated that the permanent magnet system generated normal magnetic field distributions on the plasma surface exhibiting pronounced non-axisymmetric characteristics,with spa-tial variation ranges spanning both positive and negative polarity regions.The normalized root mean square error between simulation results and REGCOIL_PM calculations remained below 5%,while the maximum relative deviation from the ideal plasma confinement magnetic field distribution was similarly controlled within 5%,meeting the engineering require-ments for magnetic field accuracy in magnetic confinement fusion.The magnetic field distribution successfully reproduced the multiple periodicity features characteristic of stellarator configurations.Spatial error distribution analysis revealed that regions with dramatic magnetic field gradient variations and high-curvature locations at the plasma boundary exhibited rela-tively larger errors,primarily attributed to the combined effects of geometric discretization deviations,magnetization vector interpolation errors,and finite element mesh resolution.Regarding the additive manufacturing scheme,laser powder bed fu-sion and other additive manufacturing processes were proposed for direct fabrication of neodymium-iron-boron or aluminum-nickel-cobalt permanent magnets.To address the technical challenge of spatially varying magnetization direc-tions,a multi-degree-of-freedom programmable magnetization system was designed,employing a closed-loop control method combining iterative magnetization with full-field measurement to compensate for cross-coupling effects during the magnetization process.This research established a complete technical framework for complex curved surface permanent magnets in stellarators,spanning from optimization design and numerical simulation to additive manufacturing,validated the technical feasibility of replacing coil magnets with permanent magnets,and provided a novel permanent magnet technol-ogy solution for magnetic confinement fusion devices.关键词
仿星器/永磁体/磁场分布/有限元仿真/增材制造Key words
stellarator/permanent magnet/magnetic field distribution/finite element simulation/additive manufacturing分类
能源科技
