SOLUTIONS TO BI-MAXWELLIAN TRANSPORT-EQUATIONS FOR RADIAL SOLAR-WIND BEYOND 28-RS

There have been numerous attempts to model the solar wind using closed self-consistent sets of transport equations. These models have employed coupled continuity, momentum and energy equations. If stress and heat flow effects have been accounted for at all, it has usually been done in a simplistic and/or empirical fashion. Sets of transport equations that are based on a higher-order approximation to the velocity distribution function can include stress and heat flow equations in a self-consistent way, thus putting the stress and heat flow moments on an equal footing with the number density, drift velocity and temperature. Such equations are capable of describing both collisionless and collision-dominated plasmas as well as the transition between these two regimes. We present solar wind solutions for radial flow between 28 solar radii and 1 a.u. using the bi-Maxwellian based 16-moment set of transport equations. In addition to the number density, drift velocity and parallel and perpendicular temperatures, the 16-moment equations account for the transport of both longitudinal and transverse thermal energies as well as stress. Also, using the 16-moment approximation for the distribution function and assuming plasma parameter values characteristic of the solar wind, we generate contour plots for the proton velocity distribution function and show how the shape of these plots depends on various macroscopic plasma parameters.