Nonlinear saturation of ideal interchange modes in a sheared magnetic field

Journal Article · Sat Jun 01 00:00:00 EDT 1991 · Physics of Fluids B; (USA)

DOI:https://doi.org/10.1063/1.859708· OSTI ID:5460067

Beklemishev, A D ^[1]

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1. Institute for Fusion Studies, The University of Texas at Austin, Austin, Texas 78712 (USA)

Pressure-driven ideal modes cannot completely interchange flux tubes of a sheared magnetic field; instead, they saturate, forming new helical equilibria. These equilibria are studied both analytically and numerically with reduced magnetohydrodynamic equations in a flux-conserving Lagrangian representation. For unstable localized modes, the structure of the nonlinear layer generated around the resonant flux surface depends on the value of Mercier parameter {ital D}{sub M}. The shape of magnetic surfaces in the vicinity of resonance is changed significantly even close to the instability threshold. However, the radial width of the affected layer becomes exponentially small near the threshold. The appearance of sheet currents and islandlike structures along the resonant flux surface may be of interest for the description of forced reconnection in models with finite resistivity. This study also includes the case of ballooning instability by representing nonlocal driving terms through the matching parameter {Delta}{prime}, which defines the outer boundary conditions for the interchange layer.

• DOE Contract Number: FG05-80ET53088
• OSTI ID: 5460067
• Journal Information: Physics of Fluids B; (USA), Vol. 3:6; ISSN 0899-8221
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
FLUTE INSTABILITY
SATURATION
PLASMA
NONLINEAR PROBLEMS
ANALYTICAL SOLUTION
ASPECT RATIO
BOUNDARY CONDITIONS
EQUATIONS
EQUILIBRIUM
HELICAL CONFIGURATION
MAGNETIC FIELDS
MAGNETIC RECONNECTION
MAGNETIC SURFACES
MAGNETOHYDRODYNAMICS
NUMERICAL SOLUTION
SHEAR
TOKAMAK DEVICES
CLOSED PLASMA DEVICES
CONFIGURATION
FLUID MECHANICS
HYDRODYNAMICS
INSTABILITY
MAGNETIC FIELD CONFIGURATIONS
MECHANICS
PLASMA INSTABILITY
PLASMA MACROINSTABILITIES
THERMONUCLEAR DEVICES
700107* - Fusion Energy- Plasma Research- Instabilities
640430 - Fluid Physics- Magnetohydrodynamics