Study of MHD activity in the HT-7 superconducting tokamak

• Published in: Physics letters. A Vol. 342; no. 1; pp. 175 - 180
• Main Authors: Asif, M., Gao, X., Li, J.G., Wan, B.N., HT-7 Team
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 04.07.2005
• Subjects: Characteristic time; Disruptions; Magneto-hydrodynamic; Mirnov coil; 52.55.Fa; 52.70.Ds; Mirnov coil; 52.35.Py; 52.35.Mw; Magneto-hydrodynamic; Characteristic time; Disruptions
• ISSN: 0375-9601; 1873-2429
• DOI: 10.1016/j.physleta.2005.05.032

An attempt is made to explain the behavior of the magneto-hydrodynamic (MHD) instabilities observed at values of the edge safety factor 3 < q ( a ) < 4 , on the HT-7 superconducting tokamak. For the poloidal-magnetic-field fluctuations observed at the Mirnov coils, Mirnov-coil analysis shows that the MHD activity consists predominantly of m = 2 mode. Estimates are given for the characteristic growth time of the m = 2 mode, τ g , and the related rate of island growth, d W / d t . The experimental value of τ g is found to be smaller than the linear theoretical one, and thus satisfy the condition τ A < τ g < τ S (where ideal timescale is τ A , and the resistive timescale is τ S ). However, the experimental and theoretical calculation of d W / d t are found to be in reasonable agreement with each other.