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

Technical Report · Wed Aug 01 00:00:00 EDT 1990

OSTI ID:6631696

Sundaram, A K; Callen, J D

The theory of resistive ballooning modes relevant to the banana-plateau collisionality regime is studied using the recently developed neoclassical MHD 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 V{sub {parallel}i}, the vector potential 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 s}, where {omega}{sub s} = sc{sub s}/qR{sub 0}, s is the shear parameter, c{sub s} the sound speed and qR{sub 0} 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 ({upsilon}{sub e} + {mu}{sub e}){sup 1/2} is possible, where {upsilon}{sub e} is the electron collision frequency and {mu}{sub 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} dlnP{sub 0}/dlnq {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 is briefly pointed out. 17 refs.

• Research Organization: Wisconsin Univ., Madison, WI (USA)
• Sponsoring Organization: DOE/ER
• DOE Contract Number: FG02-86ER53218
• OSTI ID: 6631696
• Report Number(s): UW-CPTC-90-6; ON: DE90016672
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700101 -- Fusion Energy-- Plasma Research-- Confinement
Heating
& Production
700107* -- Fusion Energy-- Plasma Research-- Instabilities
BALLOONING INSTABILITY
BANANA REGIME
BEAM INJECTION HEATING
CLOSED PLASMA DEVICES
COLLISIONS
CONFINEMENT
DIFFERENTIAL EQUATIONS
DISPERSION RELATIONS
ELECTRON COLLISIONS
EQUATIONS
EQUILIBRIUM
HEATING
INSTABILITY
MAGNETIC FIELDS
MHD EQUILIBRIUM
NEOCLASSICAL TRANSPORT THEORY
PLASMA CONFINEMENT
PLASMA HEATING
PLASMA INSTABILITY
PLASMA MACROINSTABILITIES
PRESSURE GRADIENTS
THERMONUCLEAR DEVICES
TOKAMAK DEVICES
TRANSPORT THEORY
TRAPPING