FREQUENCY CHANGE AND REFRACTION OF RADIO-WAVES PROPAGATING IN SOLAR-WIND PLASMA

Measurements of the <<Venera-15, 16>> Radjo-Science Experiment, consisting of the Doppler frequency shift of the decimeter radio waves of the Venera spacecraft during propagation in the solar corona plasma, are analyzed and interpreted. It is shown that the motion of the radio line in the direction of increasing electron density of solar corona during approach of the line of sight to the Sun produces the positive shift of the mean frequency. As the radio line moved away from the Sun we observed the frequency decrease. The regular structure of the solar corona has an influence on the frequency change and refraction of the decimeter radio signals when the impact parameter (i.e. the minimum distance from the Sun to the line of sight) is less than 6 solar radii R circle dot. The measured frequency shifts at large radial distances are associated with large-scale plasma formations which move with large velocities. The typical values of frequency are (2,5 divided-by 3,0) Hz for impact parameters of about 3 solar radii. The values of the refraction angle are presented for different impact parameters of the radio line.