Interplanetary plasma irregularities and ion acoustic turbulence

Abstract

In this paper we discuss an effect of the ion acoustic turbulence on the inhomogeneous stucture of complementary ionized interplanetary and interstellar plasmas. These media are practically collisionless and their irregularities are of scales (along the magnetic field lines) much smaller than the mean free path of the electrons. However, the presence of turbalence in the plasma, for example, ion acoustic turbulence, leads to particle collision frequencies which are anomalously large (in comparison with the Coulomb collision frequencies) due to the interaction of particles with waves. In section 2 we discuss the inhomogeneous structure of the interplanetary and interstellar plasmas. In section 3 we give the theory of low-frequency waves in plasmas and discuss the variety of wave types in the cosmic medium. Here the problems of identification and origin of the ion acoustic turbulance which was detected in the solar wind during the Helios and Voyager spacecraft experiments are emphasized. In section 4 we present a brief review of possible generation mechanisms of some types of instabilities in the interplanetary plasma associated mainly with the non-Maxwellian character of the electron and ion distribution functions. In section 5 we explain the foundations of the concept of the anomalous resistivity of a turbulent plasma. In section 6 we discuss the effect of ion sound on the properties of the solar wind. The formation of the inhomogeneous structure of the interplanetary and interstellar plasmas in the presence of developed turbulence is considered. The radio wave back scattering method is suggested for studying ion acoustic turbulance in the interplanetary and magnetospheric plasmas using ground-based sources of electromagnetic radiation. In section 7 we discuss prospects using the terrestrial ionsphere as a laboratory for modelling the dynamic processes in space plasma.