Study of Helium Abundance in Low-Speed Solar Wind Streams by the Data of Prognoz-7 and Prognoz-8 Satellites

Data from the Prognoz-7 and Prognoz-8 satellites are analyzed with respect to the relative helium abundance, n α / n p , of the low-velocity solar wind in the Earth-orbit region. On the basis of the whole data set, the conclusion is confirmed that n α / n p experiences a considerable decrease when a satellite traverses a region where the interplanetary magnetic field changes sign. This line corresponds to the neutral line of the global magnetic field (the projection of the symmetry plane of the low-latitude streamer) in the solar corona (in par- ticular, at the so-called source surface located at a distance of 2.5 solar radii from the center). A possible inter- relation between n α / n p peaks and their sources at the Sun, which are located near the places of sign change of intermediate-scale magnetic fields, is noticed.