Modeling of Neoclassical Tearing Mode Stability for Generalized Toroidal Geometry

Rosenberg, A.L. ; Gates, D.A. ; Pletzer, A. ; Menard, J.E. ; Kruger, S.E. ; Hegna, C.C. ; Paoletti, F. ; Sabbagh, S.

Princeton University. Plasma Physics Laboratory.

关键词: Bootstrap Current;    Mhd Instability;    70 Plasma Physics And Fusion Technology;    43 Particle Accelerators;    Tokamaks (Nstx);   

DOI  :  10.2172/808391
RP-ID  :  PPPL-3740
RP-ID  :  AC02-76CH03073
RP-ID  :  808391

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来源: UNT Digital Library

【 摘 要 】

Neoclassical tearing modes (NTMs) can lead to disruption and loss of confinement. Previous analysis of these modes used large aspect ratio, low beta (plasma pressure/magnetic pressure) approximations to determine the effect of NTMs on tokamak plasmas. A more accurate tool is needed to predict the onset of these instabilities. As a follow-up to recent theoretical work, a code has been written which computes the tearing mode island growth rate for arbitrary tokamak geometry. It calls PEST-3 [A. Pletzer et al., J. Comput. Phys. 115, 530 (1994)] to compute delta prime, the resistive magnetohydrodynamic (MHD) matching parameter. The code also calls the FLUXGRID routines in NIMROD [A.H. Glasser et al., Plasma Phys. Controlled Fusion 41, A747 (1999)] for Dnc, DI and DR [C.C. Hegna, Phys. Plasmas 6, 3980 (1999); A.H. Glasser et al., Phys. Fluids 18, 875 (1975)], which are the bootstrap current driven term and the ideal and resistive interchange mode criterion, respectively. In addition to these components, the NIMROD routines calculate alphas-H, a new correction to the Pfirsch-Schlter term. Finite parallel transport effects were added and a National Spherical Torus Experiment (NSTX) [M. Ono et al., Nucl. Fusion 40, 557 (2000)] equilibrium was analyzed. Another program takes the output of PEST-3 and allows the user to specify the rational surface, island width, and amount of detail near the perturbed surface to visualize the total helical flux. The results of this work will determine the stability of NTMs in an spherical torus (ST) [Y.-K.M. Peng et al., Nucl. Fusion 26, 769 (1986)] plasma with greater accuracy than previously achieved.