Optimal design and experimental testing of EMPI system for plasma disruption mitigation on J-TEXT

• Published in: Fusion engineering and design 2024-11, Vol.208, p.114701, Article 114701
• Main Authors: Yu, Y.L., Chen, Z.Y., Yan, W., Xia, S.G., Wang, N.C., Nie, Z.S., Zhou, X., Sheng, Y., Sun, Y.W., Fang, J.G., Zhong, Y.
• Format: Article
• Language: English
• Subjects: Armature recycling; Augmented electromagnetic railgun; Disruption mitigation; Electromagnetic pellet injection system; Tokamak
• ISSN: 0920-3796
• DOI: 10.1016/j.fusengdes.2024.114701

•Optimizing the first Electromagnetic Pellet Injection System, and developing a second generation EMPI.•Through simulation analysis and experimental verification, the curved recovery rail is designed, which can ensure that the armature can be recovered smoothly. Vacuum systems also were designed and tested.•According to the optimization plan, the second generation EMPI was built and related tests were carried out.•The test results have shown that the maximum current of the new EMPI has been reduced by about 60%, and the maximum speed has been increased by about 20%. The launch performance of EMPI has been improved. Plasma disruptions can cause significant damage to tokamak. Currently, the primary method for mitigating disruptions is the injection of a substantial amount of impurities. The electromagnetic injection method offers a high injection speed and rapid response time, making it a promising technique for impurity injection. The first Electromagnetic Pellet Injection System (EMPI), developed by the J-TEXT team, is capable of launching pellets at high velocities and features a specialized deceleration rail that ensures safe separation of the armature and pellet. However, this system lacks an armature recovery device and a vacuum system. In this work, a second generation EMPI has been developed, which has a vacuum system and a curved recovery rail. The curved recovery rail facilitates the smooth retrieval of the armature, enhancing the safety of the recycling process. Additionally, this new system employs an augmented rail design that improves launch performance. Test results indicate that the maximum current of the new EMPI has been reduced by approximately 60%, while the maximum launch speed has increased by around 20%.