Observation of flux tube crossings in the solar wind

TL;DR

This study uses Wind spacecraft data to identify flux tube crossings in the solar wind, providing evidence that the solar wind is structured into flux tubes with distinct plasma populations.

Contribution

It offers the first detailed analysis of flux tube crossings in the solar wind, supporting the flux tube model of solar wind structure.

Findings

Identification of two flux tube crossing events

Evidence supporting flux tubes as fundamental solar wind structures

Enhanced understanding of current sheet origins in the solar wind

Abstract

Current sheets are ubiquitous in the solar wind.They are a major source of the solar wind MHD turbulence intermittency. They may result from non-linear interactions of the solar wind MHD turbulence or are the boundaries of flux tubes that originate from the solar surface. Some current sheets appear in pairs and are the boundaries of transient structures such as magnetic holes and reconnection exhausts, or the edges of pulsed Alfv\'{e}n waves. For an individual current sheet, discerning whether it is a flux tube boundary or due to non-linear interactions, or the boundary of a transient structure is difficult. In this work, using data from the {\sl Wind} spacecraft, we identify two three-current-sheet events. Detailed examination of these two events suggest that they are best explained by the flux tube crossing scenario. Our study provides a convincing evidence supporting the scenario that the solar wind consists of flux tubes where distinct plasmas reside.