Turbulence Damping in A Weakly Ionized Plasma with A Temperature Gradient

Abstract

A theoretical model was developed to explain the damping of the motion of a turbulent fluid lump in partially ionized mangnetohydrohynamic (MHD) plasma flows with the spatial gradient of the electrical conductivity. The model was based upon the Prandtl mixing length theory. The Lagrangian equation of motion for the lump was solved for the damped fluctuating velocity. The solution of a turbulent eddy velocity was averaged over its lifetime, and successively averaged in the fluctuation velocity space. Such procedures resulted in a steady mass flow along the spatial gradient of the electrical conductivity in the presence of the magnetic field due to anisotropic turbulence suppression. The approximated magnitude of the steady mass flow directed from the electrode wall to the core region was then evaluated. Simple expressions for the damped Reynolds stress and its damping coefficient tensor have also been presented.