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Physical Review E

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Plasma (Ionized gases), Diffusion -- Magnetohydrodynamics, Thermal diffusity


A recent hydrodynamic theory of multicomponent diffusion in multitemperature gas mixtures [J. D. Ramshaw, J. Non-Equilib. Thermodyn. 18, 121 (1993)] is generalized to include the velocity-dependent Lorentz force on charged species in a magnetic field B. This generalization is used to extend a previous treatment of ambipolar diffusion in two-temperature multicomponent plasmas [J. D. Ramshaw and C. H. Chang, Plasma Chem. Plasma Process. 13, 489 (1993)] to situations in which B and the electrical current density are nonzero. General expressions are thereby derived for the species diffusion fluxes, including thermal diffusion, in both single- and two-temperature multicomponent magnetohydrodynamics (MHD). It is shown that the usual zerofield form of the Stefan-Maxwell equations can be preserved in the presence of B by introducing generalized binary diffusion tensors dependent on B. A self-consistent effective binary diffusion approximation is presented that provides explicit approximate expressions for the diffusion fluxes. Simplifications due to the small electron mass are exploited to obtain an ideal MHD description in which the electron diffusion coefficients drop out, resistive effects vanish, and the electric field reduces to a particularly simple form. This description should be well suited for numerical calculations.


This work was authored as part of the Contributor's official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law.

© 1996 AIP Publishing LLC. This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. The following article appeared in Physical Review E and may be found at:

* At the time of publication John D. Ramshaw was affiliated with the Idaho National Engineering Laboratory



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