Investigating the possible flux tube substructure of the solar wind

It has been theorised that the solar wind is made up of entangled ‘flux tubes’ (Borovsky, 2008). It is thought that these structures may be formed at the Sun and travel outwards with the solar wind, resulting in a solar wind substructure in which the larger observed discontinuities are in-fact tube interfaces. Each of these flux tubes should then also contain its own distinct plasma population, provided magnetic reconnection between flux tubes does not occur in the time taken to advect outwards with the solar wind. The nature of the observed discontinuities in the solar wind, and where indeed their origins lie, has significant implications with regard to both the transport of particles away form the Sun and to the development of solar wind turbulence. We examine Helios data, obtained in the region of 0.3 to 1 AU, and Cassini data, obtained in the region of 1 to 9 AU. Thereby enabling evaluation at different heliocentric distances of the discontinuity criteria used to detect possible flux tube boundaries, and hence further investigation of the viability of flux tube existence within the solar wind. We also use the established interface criteria to investigate the possible flux tubes themselves, in particular we examine the strahl electrons found within these boundaries. We thus present both an examination of the radial evolution of these structures and a comparison of observed properties within adjacent flux-tube-like structures.