Role of collisionless heat flux in magnetospheric convection

A fluid model of magnetospheric convection appropriate for the inner magnet osphere, including the effects of heat flux in collisionless plasma, is pre sented. The plasma is assumed to be isotropic, with the flow speed much les s than the thermal speed, and parallel electric fields and loss cone effect s are neglected; the effects of slow time variations of the magnetic field are included. The classical transport coefficients are considered and, exce pt for the collisionless heat flux, shown to be negligible in plasma in the inner magnetosphere. Beginning with three-dimensional two-fluid equations, we derive two-dimensional equations for transport of mass and energy mappe d to the magnetospheric equator. The equation of mass transport, derived fr om the mass conservation equations, is equivalent to those obtained in prev ious studies [e.g., Peymirat and Fontaine, 1994]. The equation of energy tr ansport contains the effects of collisionless heat conduction that represen ts the transport of energy in the rest frame of the species and has hithert o been neglected in magnetospheric fluid and MHD models. The energy transpo rt equation is shown to be equivalent to that of Peymirat and Fontaine [199 4] if the heat flux is neglected. The two equations are coupled first-order partial differential equations; they can be uncoupled by taking linear com binations. The uncoupled equations show that the effect of the collisionles s heat flux is to spread information across the fluid drift paths in a mann er quite different from that of fluid flow neglecting heat flux.