Nonlinear coupling of tearing modes with self-consistent resistivity evolution in tokamaks
The nonlinear interaction of tearing modes of different helicity is studied for realistic values of the tokamak parameters of resistivity and parallel heat conduction. The self-consistent evolution of the resistivity is taken into account through the electron heat conduction equation. For equilibrium q profiles inferred from electron temperature profile measured before a tokamak disruption, the essential result is that the (m = 2; n = 1) model nonlinearly destabilizes other modes on a rapid time scale. Because of the development of magnetic islands of different helicity, the toroidal current density is severely deformed. These islands overlap and field lines become stochastic in a sizable plasma volume, flattening the temperature profile in this region through parallel heat transport. The deformation of the toroidal current produces a rapid decrease in the self-inductance of the plasma, and the voltage at the limiter decreases, becoming increasingly negative. An extensive survey of equilibria and initial conditions has been conducted, and a simple prescription for their nonlinear stability properties is given.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- DOE Contract Number:
- W-7405-ENG-26
- OSTI ID:
- 5501344
- Report Number(s):
- ORNL/TM-7161; TRN: 80-005462
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
TEARING INSTABILITY
NONLINEAR PROBLEMS
TOKAMAK DEVICES
COUPLING
ELECTRIC CONDUCTIVITY
ELECTRIC POTENTIAL
LIMITERS
MAGNETIC ISLANDS
CLOSED PLASMA DEVICES
ELECTRICAL PROPERTIES
INSTABILITY
MAGNETIC FIELD CONFIGURATIONS
PHYSICAL PROPERTIES
PLASMA INSTABILITY
PLASMA MACROINSTABILITIES
THERMONUCLEAR DEVICES
700107* - Fusion Energy- Plasma Research- Instabilities