Researchers led by Prof. XU Guosheng from the Hefei Institutes of Physical Science (HFIPS) of the Chinese Academy of Sciences have recently demonstrated a novel "two-step" magnet design strategy to design advanced stellarator with standardized permanent magnet blocks and simple coils. Related results were published on Cell Reports Physical Science.

In the recent two years, permanent magnet was introduced to help simplify the complicated 3D coils of the stellarators and some designs have been proposed. However, previous magnet designs are far from engineering implementation due to the complicated forms of the permanent magnet blocks. Scientists have been considering standardizing magnet blocks with regular shapes and sizes, uniform magnetization and finite discrete magnetization orientations for mass production.

This "two-step" design strategy is proposed based on the "divide and conquer strategy" principle. It divided the design of large number of magnet blocks into independent designs of each magnet block. Thus, the standardized magnet blocks can be regularly customized for stellarator design.

Moreover, the permanent blocks can be automatically arranged in Halbach arrays to obtain higher field strength.

Based on the new strategy, the scientists came up with the same cube magnet blocks, which is the simplest form for mass production. Assembled like LEGO, the blocks can improve assembly precision control and reduce technical barriers for stellarator construction.  

Compared with the previous designs, this new design significantly reduced the engineering difficulties and costs in design, construction, assembly and maintenance of the stellarator, which is important for future stellarator development.

Compared with the previous design, the new design greatly reduces the engineering difficulty and cost in the design, construction, assembly and maintenance of the stellarator, which is of great significance for future stellarator development.  

Quasi-axisymmetric stellarator designed with identical cubic permanent magnet blocks and planar coils. (Image by LU Zhiyuan)