The evolution of resistive ballooning modes in the banana-plateau collisionality regime

Journal Article · Fri Feb 01 00:00:00 EST 1991 · Physics of Fluids B; (USA)

DOI:https://doi.org/10.1063/1.859743· OSTI ID:6251829

Sundaram, A K; Callen, J D ^[1]

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1. Departments of Nuclear Engineering and Engineering Physics and Physics, University of Wisconsin, Madison, Wisconsin 53706-1687 (US)

The theory of resistive ballooning modes relevant to the banana-plateau collisionality regime is studied using the recently developed neoclassical magnetohydrodynamics equations. Employing the ballooning mode formulation and a multiple length scale analysis, a generalized set of poloidal flux surface-averaged equations coupling the parallel ion flow velocity {ital V}{sub {parallel}{ital i}}, the vector potential {ital A}{sub {parallel}}, and the electrostatic potential {phi} are derived. A particularly simple case in which the parallel sound wave coupling reduces the order of the differential equation in the frequency range {vert bar}{omega}{vert bar}{much gt}{omega}{sub {ital s}}, where {omega}{sub {ital s}}={ital sc}{sub {ital s}}/{ital qR}{sub 0}, {ital s} is the shear parameter, {ital c}{sub {ital s}} is the sound speed, and {ital qR}{sub 0} is the connection length, is dealt with. The calculations show that a new class of localized pressure-gradient-driven ballooning modes with growth rates varying as ({nu}{sub {ital e}}+{mu}{sub {ital e}}){sup 1/2} is possible, where {nu}{sub {ital e}} is the electron collision frequency and {mu}{sub {ital e}} is the electron neoclassical poloidal flow viscous damping frequency. It is shown that the resistive ballooning modes are sensitive to variations of a parameter {eta} (={vert bar}{ital d} ln {ital P}{sub 0}/{ital d} ln {ital q}{vert bar}) within the tokamak plasma. The enhanced ion polarization and pinch type currents are found to cause stabilization of resistive modes. Further, our model highlights a smooth transition from the Pfirsch--Schlueter to the (neoclassical) banana-plateau collisionality regimes. The relevance of these results to ISX-B experiments (Phys. Rev. Lett. {bold 50}, 503 (1983)) is briefly pointed out.

• DOE Contract Number: FG02-86ER53218
• OSTI ID: 6251829
• Journal Information: Physics of Fluids B; (USA), Vol. 3:2; ISSN 0899-8221
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
COLLISIONAL PLASMA
BALLOONING INSTABILITY
BANANA REGIME
DAMPING
ELECTRON COLLISIONS
EQUILIBRIUM
ISX TOKAMAK
MAGNETOHYDRODYNAMICS
PLATEAU REGIME
TOKAMAK DEVICES
VISCOSITY
CLOSED PLASMA DEVICES
COLLISIONS
FLUID MECHANICS
HYDRODYNAMICS
INSTABILITY
MECHANICS
PLASMA
PLASMA INSTABILITY
PLASMA MACROINSTABILITIES
THERMONUCLEAR DEVICES
THERMONUCLEAR REACTORS
TOKAMAK TYPE REACTORS
TRAPPING
700108* - Fusion Energy- Plasma Research- Wave Phenomena
700107 - Fusion Energy- Plasma Research- Instabilities