Magnetogasdynamic boundary condition for a self-consistent solution to the closed magnetopause

Abstract

The conventional numerical inviscid blunt-body problem is used as an analog for the problem of the solar plasma flow around the geomagnetic cavity. The approach of Spreiter and Jones is extended (using the identical solution of Inouye and Lomax) for an assumed teardrop magnetospheric boundary. After the macroscopic flow properties are defined in the absence of an interplanetary field, the simplest case of a radial interplanetary magnetic field as suggested by Lees is considered together with a quiet Alfven Mach number in order to find a firstorder approximation to the exact magnetic field configuration for an infinitely conducting neutral plasma. The sum of both gasdynamic and magnetic pressures along the assumed boundary is then proposed as a necessary first step in a self-consistent iterative solution of the inner and outer time-independent magnetospheric problem. Exact post shock magnetic magnitudes and directions are compared with the first-order solution when the analogderived shock is assumed to be the exact fast magnetogasdynamic shock wave. This comparison indicates the validity of the approximate solution. The energy dissipated in the shock wave is found to be ^10 ergs/sec, which is approximately 20% of the proton energy flux through a circle with the diameter of the magnetosphere. An example of the threedimensional magnetic field topology also is considered for the case where the interplanetary field is perpendicular to the solar wind direction.