Verified superb condition of the KSTAR Superconducting Magnet

Newswise — The Korea Institute of Fusion Energy (KFE) announced that they have experimentally verified that KSTAR's superconducting magnets maintain maximum performance even after 16 years of continuous operation.

KSTAR’s superconducting magnets are composed of bundles of 0.8 mm superconducting wires, each coated with a 2-micrometer-thick layer of chromium to ensure insulation. However, with repeated exposure to high magnetic field operations, the quality of this chromium insulation layer can degrade, leading to increased AC loss—energy loss occurring in electrical equipment or circuits when AC current flows—and causing temperature rises in the superconducting magnets, which could impose operational constraints.

Since KSTAR began operations in 2008, its superconducting magnets have been subjected to extreme fusion environments, including high currents and strong magnetic fields. To monitor for performance degradation, the KSTAR research team measures AC loss at approximately 15kA annually.

This year, to directly assess the performance of the superconducting magnets, an experiment was conducted where the current in the core solenoid magnet was gradually increased from 15kA to the rated current of 25kA. If the superconducting state of the magnets were to break or if the thermal load were to increase, it would indicate a degradation in performance.

The experimental results demonstrated that even at a current of 25kA, all data indicating the state of the superconducting magnets remained stable. Furthermore, the total heat generated due to AC loss was reduced compared to previous measurements, experimentally confirming that the magnets have become even more stable.

The consistent performance of KSTAR’s superconducting magnets over 34,000 plasma experiments during 16 years can be attributed to the excellence of Korea’s superconducting magnet manufacturing technology and the reliable operational capabilities of the KSTAR device. This stability is considered a positive indicator for future KSTAR operations.

Moreover, these findings suggest that by understanding the characteristics of superconducting magnets and establishing clear operational guidelines, fusion reactor superconducting magnets can minimize performance issues and ensure long-term stability.

Dr. Hyun Jung Lee, head of the Superconducting Systems Research Group, stated, “The data obtained from KSTAR operations will be a valuable future asset for ITER superconducting magnet operations and the construction of superconducting magnets for fusion demonstration reactors.”

KFE President Dr. Yeongkook Oh remarked, “The innovative challenge of adopting new superconducting magnets during the construction of KSTAR has produced the excellent results we see today. We will do our utmost to realize fusion energy using KSTAR’s data and experience, which will serve as important assets.”

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The Korea Institute of Fusion Energy(KFE) is Korea's only research institute specializing in nuclear fusion. Based on our development and operation of KSTAR, a superconducting fusion research device, the KFE seeks to achieve groundbreaking research results, develop core technology for commercializing nuclear fusion, and train outstanding nuclear fusion personnel. In addition, the institute is spearheading a joint effort to open the era of nuclear fusion energy in the mid-21st century through active participation in the ITER Project.