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**Session 6 - Corona I.**

*Oral session, Friday, June 27*

*Ballroom A, Chair: David Alexander*

## [6.04] MHD Modeling of the Transition Region Using Realistic Transport Coefficients

*M. L. Goodman (Computer Sciences Corporation, and NASA Goddard Space Flight Center)*
Most of the transition region (TR) consists of a collision
dominated plasma. The dissipation and transport of energy
in such a plasma is accurately described by the well known
classical transport coefficients which include the
electrical and thermal conductivity, viscosity, and thermo-
electric tensors. These tensors are anisotropic and are
functions of local values of temperature, density, and
magnetic field. They may be used in an MHD model to obtain a self consistent,
physically realistic description of the TR. The physics of
kinetic processes is included in the MHD model through the
transport coefficients. As a first step in studying heating
and cooling processes in the TR in a realistic, quantitative
manner, a 1.5 dimensional, steady state MHD model with a
specified temperature profile is considered. The momentum
equation includes the inertial, pressure gradient, Lorentz,
and gravitational forces. The Ohm's law includes the exact
expressions for the electrical conductivity and thermo-
electric tensors. The electrical conductivity relates the
generalized electric field to the conduction current density
while the thermo-electric tensor relates the temperature
gradient to the thermo-electric current density. The total
current density is the sum of the two. It is found that the
thermo-electric current density can be as large as the
conduction current density, indicating that thermo-electric
effects are probably important in modeling the dynamics of
energy dissipation, such as wave dissipation, in the TR.
Although the temperature gradient is in the vertical
direction, the thermo-electric current density is in the
horizontal direction, indicating the importance of the
effects of anisotropic transport. The transport coefficients
are valid for all magnetic field strengths, and so may be
used to study the physics of weakly as well as strongly
magnetized regions of the TR. Numerical examples are
presented.

The author(s) of this abstract have provided an email address for comments about the abstract: goodman@spof02.gsfc.nasa.gov

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