IT Home January 27 news, according to the voice of the Chinese Academy of Sciences, recently, the Chinese Academy of Sciences Hefei Research Institute integrated permanent magnets and simple coils of advanced star imitator design research progress.
IT House learned that the most common design for reactors is called the Tokamak device, which is a hollow metal structure similar to a circular coil. When the fuel is heated to more than 150 million degrees Celsius, it can form a high-temperature plasma. The continent's "artificial sun" fully superconducting tokamak nuclear fusion experimental device (EAST) enables 1056 seconds of long-pulse high-parameter plasma operation.
▼ "Artificial Sun" Full Superconducting Tokamak Nuclear Fusion Experimental Device (EAST)
Although the tokamak device ideally constrains this plasma, it also exposes some safety risks, such as the immediate collapse of the magnetic field when the current fails.
The star-replicator is a magnetically constrained nuclear fusion pathway with fusion three-product parameters second only to tortamak, which has the advantage of steady-state operation compared to tokamak and avoids the main disadvantage of tokamak: large plasma rupture. However, for a long time, the star-replicator has not been the first choice as the technical route of the fusion reactor, mainly for two reasons:
First, the ripple of the magnetic field of the traditional star-imitator is larger than that of the tokamak, resulting in its new classical transport level and high-energy particle loss level being higher than that of the tokamak.
Second, the star imitator requires a three-dimensional structure of the coil, the structure is complex, the manufacturing is difficult, and the cost is high.
In response to these two difficulties, researchers have carried out research and made progress in the preliminary work. For a long time, the field of stellar-replicator research has tried to reduce the new classical transport level of the stellar-imitator and the level of loss of high-energy particles by optimizing the magnetic field shape. The study found that accurate quasi-symmetry can be achieved by optimizing the magnetic field shape of the star-replicator, which proves that the star-replicator can achieve the same level of new classical transport and the level of high-energy particle loss (Physical Review Letters) comparable to that of the tokamak.
The star-replicator combining the permanent magnet is a hot spot in the field of international star-replicator research, and how to generate the required three-dimensional magnetic field with a simple engineering permanent magnet block is a research difficulty. Recently, Xu Guosheng's research group proposed a standardized permanent magnet design strategy for the first time. The strategy adopts the idea of "divide and conquer", decomposing the design process of the permanent magnet block into designing each permanent magnet one by one, and then iterating multiple times to obtain the optimal design, the iterative process includes two parts: local optimization and global optimization.
▼ Advanced star-replicator design with integrated permanent magnet and simple coil
This idea is easy to highly define the specific form of each permanent magnet, and directly take the engineering realization as the starting point for permanent magnet design. Based on this design strategy, Xu Guosheng's research group has realized the standardization of the permanent magnet of the star-replicator, that is, the size and shape of all permanent magnet blocks, the residual magnetic intensity are exactly the same, and the magnetization direction is one of the specified directions of a limited number of specified directions. The design allows permanent magnet blocks to be mass-produced, reducing manufacturing costs. In addition, the unified size and shape make the permanent magnet block can be assembled, which is conducive to the control of assembly accuracy. The research will help the permanent magnet star imitator move from the conceptual design stage to the engineering realization, and promote the development of the star imitator.
Compared with the extremely complex three-dimensional twisted coil used in the current star-replicater, the standardized magnet block that can be mass-manufactured and the low production cost and low engineering difficulty of the simple coil are of great significance to the design, construction and maintenance of the star-replicator, and the advanced star-replicator that combines the permanent magnet and the quasi-symmetrical position is expected to become a competitive low-cost steady-state magnetic confinement fusion experimental device.