Tearing mode stability studies near ideal stability boundaries in DIII-D

被引:57
作者
Brennan, DP
Strait, EJ
Turnbull, AD
Chu, MS
La Haye, RJ
Luce, TC
Taylor, TS
Kruger, S
Pletzer, A
机构
[1] Gen Atom Co, San Diego, CA 92186 USA
[2] SAIC, San Diego, CA 92186 USA
[3] Princeton Plasma Phys Lab, Princeton, NJ 08543 USA
关键词
D O I
10.1063/1.1481504
中图分类号
O35 [流体力学]; O53 [等离子体物理学];
学科分类号
070204 ; 080103 ; 080704 ;
摘要
For high beta, highly shaped plasmas in the DIII-D tokamak [J. L. Luxon and L. G. Davis, Fusion Technol. 8, 441 (1985)], the value of the tearing stability index Delta(') calculated at a rational surface can be especially sensitive to the pressure and current profiles. Near marginal stability for a global ideal mode, a pole in Delta(') exists in equilibrium parameter space, as predicted by analytic theory. The proximity of an equilibrium reconstruction to this pole in parameter space strongly decreases the accuracy of the Delta(') calculations. Tearing stability calculations on kinetic equilibrium reconstructions of a series of times in three DIII-D discharges are presented, which indicate that the tearing modes in these discharges are classically unstable at the time of onset. The onset mechanism of two of these discharges (which are in H-mode) is related to the approach of ideal stability boundaries and the occurrence of poles in Delta('). Several ideal modes (sawteeth, edge localized modes, and resistive wall modes) are thought to seed neoclassical tearing modes (NTMs) through forced reconnection, after the ideal mode is unstable. However, tearing modes often appear suddenly and grow quickly without an obvious ideal mode causing a seed island through forced reconnection, which could be explained by this mechanism. This is proposed as an alternative mechanism for the onset of NTMs in tokamaks, which is not incompatible with forced reconnection. (C) 2002 American Institute of Physics.
引用
收藏
页码:2998 / 3006
页数:9
相关论文
共 31 条
[1]  
Bateman G., 1978, MHD Instabilities
[2]   ON THE DIFFICULTY OF DETERMINING TEARING MODE-STABILITY [J].
BISHOP, CM ;
CONNOR, JW ;
HASTIE, RJ ;
COWLEY, SC .
PLASMA PHYSICS AND CONTROLLED FUSION, 1991, 33 (04) :389-395
[3]   GLOBAL ENERGY CONFINEMENT DEGRADATION DUE TO MACROSCOPIC PHENOMENA IN TOKAMAKS [J].
CHANG, Z ;
CALLEN, JD .
NUCLEAR FUSION, 1990, 30 (02) :219-233
[4]   RESISTIVE INSTABILITIES IN A DIFFUSE LINEAR PINCH [J].
COPPI, B ;
GREENE, JM ;
JOHNSON, JL .
NUCLEAR FUSION, 1966, 6 (02) :101-&
[5]   2-DIMENSIONAL GENERALIZATIONS OF THE NEWCOMB EQUATION [J].
DEWAR, RL ;
PLETZER, A .
JOURNAL OF PLASMA PHYSICS, 1990, 43 :291-310
[6]   FINITE-RESISTIVITY INSTABILITIES OF A SHEET PINCH [J].
FURTH, HP ;
KILLEEN, J ;
ROSENBLUTH, MN .
PHYSICS OF FLUIDS, 1963, 6 (04) :459-484
[7]   Complete suppression of neoclassical tearing modes with current drive at the electron-cyclotron-resonance frequency in ASDEX upgrade tokamak [J].
Gantenbein, G ;
Zohm, H ;
Giruzzi, G ;
Günter, S ;
Leuterer, F ;
Maraschek, M ;
Meskat, J ;
Yu, Q .
PHYSICAL REVIEW LETTERS, 2000, 85 (06) :1242-1245
[8]   Direct observation of the resistive wall mode in a tokamak and its interaction with plasma rotation [J].
Garofalo, AM ;
Turnbull, AD ;
Austin, ME ;
Bialek, J ;
Chu, MS ;
Comer, KJ ;
Fredrickson, ED ;
Groebner, RJ ;
La Haye, RJ ;
Lao, LL ;
Lazarus, EA ;
Navratil, GA ;
Osborne, TH ;
Rice, BW ;
Sabbagh, SA ;
Scoville, JT ;
Strait, EJ ;
Taylor, TS .
PHYSICAL REVIEW LETTERS, 1999, 82 (19) :3811-3814
[9]   Heuristic closures for numerical simulations of neoclassical tearing modes [J].
Gianakon, TA ;
Kruger, SE ;
Hegna, CC .
PHYSICS OF PLASMAS, 2002, 9 (02) :536-547
[10]   RESISTIVE INSTABILITIES IN GENERAL TOROIDAL PLASMA CONFIGURATIONS [J].
GLASSER, AH ;
GREENE, JM ;
JOHNSON, JL .
PHYSICS OF FLUIDS, 1975, 18 (07) :875-888