Intermittency in the Expanding Solar Wind: Observations from Parker Solar Probe (0.16au), Helios 1 (0.3-1au), and Voyager 1 (1-10au)

TL;DR

This study analyzes how magnetic field intermittency evolves from near the Sun to 10 astronomical units using data from Parker Solar Probe, Helios, and Voyager 1, revealing a relationship between Reynolds number and intermittency.

Contribution

It provides the first detailed analysis of the relationship between Reynolds number and magnetic intermittency across a wide heliocentric distance range.

Findings

Lower Reynolds number correlates with reduced intermittency.

Intermittency decreases with increasing distance from the Sun.

The study refines Voyager 1 magnetic field data for analysis.

Abstract

We examine statistics of magnetic field vector components to explore how intermittency evolves from near sun plasma to radial distances as large as 10 au. Statistics entering the analysis include auto-correlation, magnetic structure functions of order n (SFn), and scale dependent kurtosis (SDK), each grouped in ranges of heliocentric distance. The Goddard Space Flight Center Space Physics Data Facility (SPDF) provides magnetic field measurements for resolutions of 6.8ms for Parker Solar Probe, 6s for Helios, and 1.92s for Voyager 1. We compute SF2 to determine the scales encompassing the inertial range and examine SDK to investigate degree of non-Gaussianity. Auto-correlations are used to resolve correlation scales. Correlation lengths and ion inertial lengths provide an estimate of effective Reynolds number (Re). Variation in Re allows us to examine for the first time the relationship between SDK and Re in an interplanetary plasma. A conclusion from this observed relationship is that regions with lower Re at a fixed physical scale have on average lower kurtosis, implying less intermittent behavior. Kolmogorov refined similarity hypothesis is applied to magnetic SFn and kurtosis to calculate intermittency parameters and fractal scaling in the inertial range. A refined Voyager 1 magnetic field dataset is generated.