Study of MHD mode and cooling process during disruptions triggered by impurities injection in J-TEXT

Journal Article · 23 September 2018 · Nuclear Fusion

DOI: https://doi.org/10.1088/1741-4326/aae39a · OSTI ID:1480686

Huang, Y. ^[1]; Chen, Z. Y.  ^[2]; Hu, Qiming ^[3]; Yu, Q. ^[4]; Jiang, Z. H.  ^[1]; Wei, Y. N. ^[1]; Su, Pengjuan ^[1]; Shen, Chengshuo ^[1]; Guo, Daojing ^[1]; Yang, Z. J. ^[1]; Pan, X. M. ^[1]; Huang, Mingxiang ^[1]; Cai, Qinxue ^[1]; Wang, Tong ^[1]; Lin, Z. F. ^[1]; Tong, R. H. ^[1]; Yan, W. ^[1]; Chen, Z. P. ^[1]; Ding, Y. H. ^[1]; Liang, Y. ^[1]

---

1. Huazhong Univ. of Science and Technology, Wuhan (China). International Joint Research Lab. of Magnetic Confinement Fusion and Plasma Physics. State Key Lab. of Advanced Electromagnetic Engineering and Technology. School of Electrical and Electronic Engineering
2. Huazhong Univ. of Science and Technology, Wuhan (China). International Joint Research Lab. of Magnetic Confinement Fusion and Plasma Physics. State Key Lab. of Advanced Electromagnetic Engineering and Technology. School of Electrical and Electronic Engineering; Chengdu Univ. (China)
3. Huazhong Univ. of Science and Technology, Wuhan (China). International Joint Research Lab. of Magnetic Confinement Fusion and Plasma Physics. State Key Lab. of Advanced Electromagnetic Engineering and Technology. School of Electrical and Electronic Engineering; Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
4. Max Planck Inst. of Plasma Physics, Garching (Germany)

The injection of a large amount of impurities is one of the possible ways of mitigating disruption in large-scale tokamaks. The deposition of impurities at the center of the plasma is the key to the radiation of plasma energy and suppression of runaway. The interaction of the gas jet with the rational surfaces has been studied by scanning the plasma current. The experimental results show that the injection of a massive amount of argon can cool the plasma from the edge to the core region, and the cooling process is accompanied by different magnetohydrodynamic (MHD) modes when the gas jet reaches the corresponding rational surfaces. It is observed that with different edge safety factors and electron density, gas injection can induce different poloidal modes at first. Then, the poloidal mode traverses to lower m (where m is the poloidal mode number) MHD activities until a 2/1 mode is initiated and a thermal quench is started. The experimental results show that the penetration of a gas jet across the rational surfaces is faster in the plasmas with pre-existing large 2/1 tearing modes, which indicates that the 2/1 mode plays an important role in the penetration process. Disruptions triggered by supersonic molecular beam injection display a slower cooling process compared with massive gas injection, which can be divided into four stages. The dominant poloidal mode transition from m = 3 to m = 2 is associated with electron temperature recovery.

• Research Organization: Huazhong Univ. of Science and Technology, Wuhan (China); Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
• Sponsoring Organization: National Magnetic Confinement Fusion Science Program (China); National Natural Science Foundation of China (NSFC); USDOE
• Contributing Organization: J-TEXT Team
• OSTI ID: 1480686
• Journal Information: Nuclear Fusion, Journal Name: Nuclear Fusion Journal Issue: 12 Vol. 58; ISSN 0029-5515
• Publisher: IOP ScienceCopyright Statement
• Country of Publication: United States
• Language: English