Parker Solar Probe Observations of Helical Structures as Boundaries for Energetic Particles

TL;DR

This study uses Parker Solar Probe data to show that helical magnetic flux tubes and their boundaries influence the transport and confinement of solar energetic particles in the interplanetary medium.

Contribution

It provides observational evidence linking magnetic flux tube boundaries to energetic particle confinement, using real-space magnetic helicity and PVIs analysis.

Findings

Energetic particles are confined within or outside helical flux tubes.

Flux tube boundaries act as transport boundaries for particles.

Observations support previous theories on magnetic structures affecting particle transport.

Abstract

Energetic particle transport in the interplanetary medium is known to be affected by magnetic structures. It has been demonstrated for solar energetic particles in near-Earth orbit studies, and also for the more energetic cosmic rays. In this paper, we show observational evidence that intensity variations of solar energetic particles can be correlated with the occurrence of helical magnetic flux tubes and their boundaries. The analysis is carried out using data from Parker Solar Probe orbit 5, in the period 2020 May 24 to June 2. We use FIELDS magnetic field data and energetic particle measurements from the Integrated Science Investigation of the Sun (\isois) suite on the Parker Solar Probe. We identify magnetic flux ropes by employing a real-space evaluation of magnetic helicity, and their potential boundaries using the Partial Variance of Increments method. We find that energetic particles are either confined within or localized outside of helical flux tubes, suggesting that the latter act as transport boundaries for particles, consistent with previously developed viewpoints.