Mean-field Ohm's law and coaxial helicity injection in force-free plasmas
- Department of Radiologic Sciences, Thomas Jefferson University, 130 S. 9th Street, Philadelphia, Pennsylvania 19107-5233 (United States)
A theoretical analysis of steady-state coaxial helicity injection (CHI) in force-free plasmas is presented using a parallel mean-field Ohm's law that includes resistivity {eta} and hyper-resistivity {Lambda} terms. Using Boozer coordinates, a partial differential equation is derived for the time evolution of the mean-field poloidal magnetic flux, or magnetic Hamiltonian function, from the parallel mean-field Ohm's law. A general expression is obtained from the mean-field theory for the efficiency of CHI current drive in force-free plasmas. Inductances of internal energy, magnetic helicity, and poloidal magnetic flux are used to characterize axisymmetric plasma equilibria that have a model current profile. Using the model current profile, a method is suggested to determine the level of magnetohydrodynamic activity at the magnetic axis and the consequent deviation from the completely relaxed Taylor state. The mean-field Ohm's law model suggests that steady-state CHI can be viewed most simply as a boundary layer problem.
- OSTI ID:
- 22047129
- Journal Information:
- Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 12 Vol. 18; ISSN PHPAEN; ISSN 1070-664X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AXIAL SYMMETRY
BOUNDARY LAYERS
CHARGED-PARTICLE TRANSPORT
HAMILTONIAN FUNCTION
HELICITY
INDUCTANCE
MAGNETIC FLUX
MAGNETOHYDRODYNAMICS
MEAN-FIELD THEORY
OHM LAW
PARTIAL DIFFERENTIAL EQUATIONS
PLASMA
STEADY-STATE CONDITIONS