Turbulence in the Near-Sun Streamer Belt Solar Wind

Abstract:

The recent orbits of Parker Solar Probe have reached down to a heliocentric distance of 28 solar radii, allowing us to investigate turbulence closer to the Sun than ever before. At these distances, the spacecraft encountered the heliospheric current sheet multiple times and spent significant time in the surrounding streamer belt solar wind. The turbulence in this streamer belt wind is found to have significantly different properties to the non streamer belt wind, and in particular its overall amplitude is much smaller. This has important implications for the mechanism by which the solar wind is accelerated, suggesting a possibly different acceleration mechanism (other than Alfvenic turbulence) for this type of wind. Encounters of the heliospheric plasma sheet also allow measurements of the turbulence at far higher beta (>100) than has been possible previously, allowing different models of the kinetic range turbulence to be tested. The implications of these results for our understanding of both the fundamentals of plasma turbulence and its role in the solar wind generation will be discussed.