The National Institutes for Quantum and Radiological Science and Technology and Nippon Telegraph and Telephone Corporation have established an AI prediction method to be applied to the plasma confinement magnetic field of a large-scale nuclear fusion device.
QST and NTT signed a collaboration agreement in 2020 and have been conducting joint research aimed at creating innovative environmental energy technologies that are ahead of the world.
This time, they applied a method called Mixture of Experts (MoE), which weights and integrates the optimal AI model according to the changing situation, to establish a technology to predict plasma with high accuracy, and evaluated the actual plasma confinement magnetic field of the world’s largest tokamak type superconducting plasma experimental device JT-60SA. As a result, for the first time in the world, they succeeded in reproducing the position and shape of plasma that depend on the magnetic field structure with the accuracy required for actual plasma control. Conventional analytical reconstruction methods based on the laws of physics could in principle control the position and shape of the plasma boundary (periphery) which changes sequentially. However, this method has made it possible to control multiple control quantities in real time, including the distribution of current and pressure inside the plasma, which is important for avoiding plasma instability, something that was not possible with conventional methods.
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This result will be useful in challenging the real-time control of high-temperature plasma in future heating experiments of JT-60SA, and is a groundbreaking achievement that will lead to plasma prediction control in fusion reactors such as ETER and DEMO, which control larger plasmas with a small number of measuring instruments . In response to this result, QST and NTT have agreed to further extend the collaborative agreement they signed in 2020, and will continue to work together toward the early practical application of fusion energy.
Tokamak reactors, which are the most advanced in the world toward the prototype reactor of fusion energy, an innovative form of environmental energy, require a continuous flow of electric current in the plasma because the confinement magnetic field is formed by the current flowing in the plasma itself. However, instabilities may occur due to the current and pressure. To utilize a stable prototype reactor, it is important to predict these instabilities before they occur and control them appropriately, and the challenge was to establish a method to reconstruct the plasma confinement magnetic field required for control in real time with high accuracy from measurement signals. As one solution, this joint research has developed a method to evaluate the plasma confinement magnetic field with high accuracy using AI technology that is good at optimization problems, with the aim of utilizing it for the control of the world’s largest tokamak-type superconducting plasma experimental device JT-60SA.
SOURCE: NTT
