Development Of Advanced Stellarator With Standardized Permanent Magnet Blocks

Recent study indicates the complicated 3D coils of stellarators can be dramatically simplified by introducing permanent magnets. However, the existing designs use permanent magnets with various shapes, sizes and even arbitrary magnetization orientations, thus their fabrication and assembly may be even more difficult and costly than the 3D coils. For designing standardized permanent magnets, we have performed a series of research. The Fourier decomposition method is introduced to design perpendicular magnets [1]. The “two-step” magnet design strategy [2, 3] is proposed based on the idea of “divide and conquer strategy”, which decomposes the design of large number of magnet blocks into independent designs of each magnet, thus the standardized magnet blocks can be easily customized. This strategy can give almost the same design as the Fourier decomposition method, and most importantly, it is successfully applied to design ESTELL stellarator with identical cubic magnet blocks and a minitype stellarator with identical rectangular magnet pieces. These magnet designs will substantially reduce the difficulty and cost of magnet fabrication and assembly and potentially lower the engineering barrier for stellarator construction.