Rippling modes in the edge of a tokamak plasma
A promising resistive magnetohydrodynamic candidate for the underlying cause of turbulence in the edge of a tokamak plasma is the rippling instability. In this paper we develop a computational model for these modes in the cylindrical tokamak approximation and explore the linear growth and single-helicity quasi-linear saturation phases of the rippling modes for parameters appropriate to the edge of a tokamak plasma. Large parallel heat conduction does not stabilize these modes; it only reduces their growth rate by a factor scaling as k/sub parallel//sup -4/3/. Nonlinearly, individual rippling modes are found to saturate by quasi-linear flattening of the resistivity profile. The saturated amplitude of the modes scales as m/sup -1/, and the radial extent of these modes grows linearly with time due to radial Vector E x Vector B/sub 0/ convection. This evolution is found to be terminated by parallel heat conduction.
- Research Organization:
- Oak Ridge National Lab., TN (USA)
- DOE Contract Number:
- W-7405-ENG-26
- OSTI ID:
- 5155019
- Report Number(s):
- ORNL/TM-7989; ON: DE82007724
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
700107* -- Fusion Energy-- Plasma Research-- Instabilities
700202 -- Fusion Power Plant Technology-- Magnet Coils & Fields
CLOSED PLASMA DEVICES
ENERGY TRANSFER
HEAT TRANSFER
INSTABILITY GROWTH RATES
MAGNETIC FIELD CONFIGURATIONS
MAGNETIC FIELD RIPPLES
PLASMA SHEATH
QUASILINEAR PROBLEMS
SCALING LAWS
THERMAL CONDUCTION
THERMONUCLEAR DEVICES
TOKAMAK DEVICES
TURBULENCE