Solar wind helium observations on the Prognoz 7 satellite

Solar wind data, obtained with ion mass-energy-spectrometer on the Prognoz 7 satellite are analyzed to study the alpha-particle and proton features in different types of solar wind streams. In the streams from coronal holes the abundance of helium relative to proton slightly increases with increasing solar wind flux and proton density while in the streams from coronal streamers it decreases. Preferential alpha-particle acceleration and heating are often observed in the streams from coronal holes. Minimum (as well as negative) values of alpha-proton velocity difference are recorded in the heliospheric current sheet, shocked plasma and coronal mass ejections. Dependences of alpha-proton velocity difference and temperature ratio on several MHD parameters are comapred for different types of streams.