LARGE-SCALE SPIRAL WAVES IN THE SOLAR WIND

<正> In this paper, it is shown that the sectoral structure of the interplanetary magnetic field might be caused by the largo-scale spiral waves on the equatorial plane, The equatorial plane is a neutral sheet for the fundamental solar dipolar field. The magnetic induction on it approximates zero. However, if a spiral wave is excited in the equatorial plane, the sectoral structure with all the observed basic features would occur. Indeed, we can show the possible existence of spiral waves rotating rigidly with the sun. By using a simple model in which the viscosity and thermal conductivity are neglected, it is easy to prove that the stability of the spiral wave is neutral. According to this theory, the sectoral structure is not a matter flow but a density wave. Theoretical estimates about the wave length and pitch angle agree roughly with many of the properties of the interplanetary magnetic field obtained from space observation.