Alfvenic Fluctuations in the Inner Heliosphere: Implications for Solar Orbiter and Solar Probe Plus

Abstract:

Large amplitude Alfvenic fluctuations in high speed streams result in velocity variations of the order of the Alfven speed. Conservation of the magnetic field magnitude results, surprisingly, preferentially in velocity enhancements rather than decreases. We show that this can result in short (tens of seconds to minutes) increases of the solar wind speed of order 200 km/s in high speed wind at 0.3 AU. We discuss the consequences for determining the underlying solar wind stream structure, show how this effect is larger even closer to the Sun and predict the likely conditions to be experienced by Solar Probe Plus at 10 solar radii.