Stability Limits of High-Beta Plasmas in DIII-D

Journal Article · Sat Oct 15 00:00:00 EDT 2005 · Fusion Science and Technology

OSTI ID:20854267

Strait, E J ^[1]

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1. General Atomics (United States)

Stability at high beta is an important requirement for a compact, economically attractive fusion reactor. DIII-D experiments have shown that ideal magnetohydrodynamic (MHD) theory is an accurate predictor of the ultimate stability limits for tokamaks, and the Troyon scaling law has provided a useful approximation of ideal stability limits for discharges with 'conventional' profiles. However, variation of the discharge shape, pressure profile, and current density profile can lead to ideal MHD beta limits that differ significantly from simple Troyon scaling. The need for profiles consistent with steady-state operation places an important additional constraint on plasma stability. Nonideal effects can also be important and must be taken into account. For example, neoclassical tearing modes (NTMs), resulting from plasma resistivity and the nonlinear effects of the bootstrap current, can become unstable at beta values well below the ideal MHD limit. DIII-D experiments are now entering a new era of unprecedented control over plasma stability, including suppression of NTMs by localized current drive at the island location, and direct feedback stabilization of kink modes with a resistive wall. The continuing development of physics understanding and control tools holds the potential for stable, steady-state fusion plasmas at high beta.

• OSTI ID: 20854267
• Journal Information: Fusion Science and Technology, Vol. 48, Issue 2; Other Information: Copyright (c) 2006 American Nuclear Society (ANS), United States, All rights reserved. http://epubs.ans.org/; Country of input: International Atomic Energy Agency (IAEA); ISSN 1536-1055
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
APPROXIMATIONS
BOOTSTRAP CURRENT
CONTROL
CURRENT DENSITY
DOUBLET-3 DEVICE
FEEDBACK
HIGH-BETA PLASMA
KINK INSTABILITY
MAGNETOHYDRODYNAMICS
NEOCLASSICAL TRANSPORT THEORY
NONLINEAR PROBLEMS
SCALING LAWS
STABILITY
STABILIZATION
STEADY-STATE CONDITIONS
TEARING INSTABILITY
THERMONUCLEAR REACTORS
VARIATIONS