Effective viscosity of a streaming collision-free plasma in a weakly turbulent magnetic field

Fokker-Planck analysis is made of the effective viscosity of a streaming collision-free plasma in a weakly turbulent magnetic field. This viscosity is an effect of momentum transfer across the stream due to the scattering of guiding centers of charged particles by coherent magnetic field fluctuations of the hydromagnetic type. In the slow stream approximation, which is pertinent to the upstream face of the magnetosphere, electric field accompanying magnetosonic fluctuations can play the main role in the viscous interaction. It is concluded that there is most probably a viscous-like interaction between the solar wind and the magnetosphere.