ИСТИНА

Variations of the abundance of heavy species observed in the solar wind are usually attributed to spacecraft encounters of streams emanating from different places and altitudes in the source region and its further evolution is considered as being negligible. These conclusions are based on an analysis of highly averaged data and much less attention was devoted to variations on the time scale of seconds. The BMSW instrument onboard the Spektr-R spacecraft provides a high-time resolution data of the helium and proton fluxes and proton velocity, density, and temperature that suitable for investigations of rapid variations. The paper focuses on their statistical analysis and correlations with changes of other parameters. We have found that only a part of He abundance variations can be attributed to changes of the source region, whereas a significant portion of them could be generated by in-transit turbulence that is probably driven by the speed difference between the ion species.