PPPL-5149

Heat flux viscosity in collisional magnetized plasmas

Authors:   C. Liu, W. Fox, and A. Bhattacharjee

Abstract:   Momentum transport in collisional magnetized plasmas due to gradients in the heat flux, a "heat flux viscosity", is demonstrated. Even though no net particle flux is associated with a heat flux, in a plasma there can still be momentum transport owing to the velocity dependence of the Coulomb collision frequency, analogous to the thermal force. This heat-flux viscosity may play an important role in numerous plasma environments, in particular in strongly-driven high-energy-density plasma, where strong heat flux can dominate over ordinary plasma flows. The heat flux viscosity can influence the dynamics of the magnetic fi eld in plasmas through the generalized Ohm's law, and may therefore play an important role as a dissipation mechanism allowing magnetic field line reconnection. The heat flux viscosity is calculated directly using the fi nite-diff erence method of E. M. Epperlein and M. G. Haines [M. G. Haines, Phys. Fluids 29, 1029 (1986)], which is shown to be more accurate than S. I. Braginskii's method [S. I. Braginskii, Rev. Plasma Phys. 1, 205 (1965)], and con firmed with one-dimensional collisional particle-in-cell simulations. The resulting transport coefficients are tabulated for ease of application.
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Submitted to:  Physics of Plasmas
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