A numerical study of plasma evolutions due to resistive tearing-mode turbulence in reversed-field pinches (RFPs)

Thesis/Dissertation · Tue Jan 01 04:00:00 EST 1991

OSTI ID:5314183

Kwok, Yuchun

Macroscopic transport in RFPs due to turbulent electric fields is studied by the method of numerical simulation in a straight toroidal cylinder. A turbulent electric field model of resistive magnetohydrodynamic (MHD) tearing modes is incorporated in the 1-D quasi-equilibrium MHD equations to obtain the transport equations. Recent RFP experiments have shown that magnetic fields resisted ohmic dissipation after a screw pinch equilibrium, initially turbulent, evolved into and RFP state. The outstanding features which lack complete theories regarding the underlying mechanisms, are the instantaneous reversal of toroidal magnetic field at the transition point and the sustainment of the RFP phase which follows, two important physics issues in controlled thermonuclear fusion study. The objective of this work is to examine, through a time-dependent calculation, the effects of resistive tearing mode turbulence on the RFP evolution and explore the possibility of a dynamo action resulting form such activities in context of addressing the two issues. To alleviate a constraint imposed by the force-balance condition on the velocity variable, a Lagrangian mesh method in which the poloidal magnetic flux function serves as the spatial variable is used to integrate the set of the transport equations. Finite difference schemes are applied to obtain numerical solutions. The transport equations, scaled in some set of base units, can be parameterized by five adjustable numerical constants. These numbers measure, in simulation units, the ratio of E {times} B-drift to diffusion speed, the level of tearing mode turbulence, the applied electric field in toroidal and poloidal directions, and the position of the conducting shell relative to the plasma edge.

• Research Organization: Columbia Univ., New York, NY (United States)
• OSTI ID: 5314183
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700330* -- Plasma Kinetics
Transport
& Impurities-- (1992-)
BOUNDARY-VALUE PROBLEMS
CHARGED-PARTICLE TRANSPORT
DIFFUSION
ELECTRIC FIELDS
FINITE DIFFERENCE METHOD
FLUID MECHANICS
HYDRODYNAMICS
INSTABILITY
ION DRIFT
ITERATIVE METHODS
MAGNETIC FIELD CONFIGURATIONS
MAGNETIC FIELD REVERSAL
MAGNETIC FLUX
MAGNETOHYDRODYNAMICS
MATHEMATICAL MODELS
MECHANICS
MESH GENERATION
NUMERICAL SOLUTION
PINCH EFFECT
PLASMA INSTABILITY
PLASMA MACROINSTABILITIES
PLASMA SIMULATION
RADIATION TRANSPORT
REVERSE-FIELD PINCH
SIMULATION
TEARING INSTABILITY
TURBULENCE
ZT-40 DEVICES