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Author Wang, H. ♦ Vlad, M. ♦ Vanden Eijnden, E. ♦ Spineanu, F. ♦ Balescu, R.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword PLASMA PHYSICS AND FUSION ♦ PLASMA CONFINEMENT ♦ DIFFUSION ♦ MAGNETIC FIELDS ♦ STOCHASTIC PROCESSES ♦ FLUCTUATIONS ♦ CORRELATION FUNCTIONS ♦ INTEGRAL EQUATIONS
Abstract The statistical representation of a fluctuating (stochastic) magnetic field configuration is studied in detail. The Eulerian correlation functions of the magnetic field are determined, taking into account all geometrical constraints: these objects form a nondiagonal matrix. The Lagrangian correlations, within the reasonable Corrsin approximation, are reduced to a single scalar function, determined by an integral equation. The mean square perpendicular deviation of a geometrical point moving along a perturbed field line is determined by a nonlinear second-order differential equation. The separation of neighboring field lines in a stochastic magnetic field is studied. We find exponentiation lengths of both signs describing, in particular, a decay (on the average) of any initial anisotropy. The vanishing sum of these exponentiation lengths ensures the existence of an invariant which was overlooked in previous works. Next, the separation of a particle`s trajectory from the magnetic field line to which it was initially attached is studied by a similar method. Here too an initial phase of exponential separation appears. Assuming the existence of a final diffusive phase, anomalous diffusion coefficients are found for both weakly and strongly collisional limits. The latter is identical to the well known Rechester-Rosenbluth coefficient, which is obtained here by a more quantitative (though not entirely deductive) treatment than in earlier works.
ISSN 1063651X
Educational Use Research
Learning Resource Type Article
Publisher Date 1995-05-01
Publisher Place United States
Journal Physical Review. E, Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics
Volume Number 51
Issue Number 5


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