Reynolds Number and Intermittency in the Expanding Solar Wind: Predictions Based on <i>Voyager</i> Observations

Author
Keywords
Abstract
<p>The large-scale features of the solar wind are examined in order to predict small-scale features of turbulence in unexplored regions of the heliosphere. The strategy is to examine how system size, or effective Reynolds number Re, varies, and then how this quantity influences observable statistical properties, including intermittency properties of solar wind turbulence. The expectation based on similar hydrodynamics scalings is that the kurtosis, of the small-scale magnetic field increments, will increase with increasing Re. Simple theoretical arguments as well as Voyager observations indicate that effective interplanetary turbulence Re decreases with increasing heliocentric distance. The decrease of scale-dependent magnetic increment kurtosis with increasing heliocentric distance is verified using a newly refined Voyager magnetic field data set. We argue that these scalings continue to much smaller heliocentric distances approaching the Alfv\ en critical region, motivating a prediction that the Parker Solar Probe spacecraft will observe increased magnetic field intermittency, stronger current sheets, and more localized dissipation, as its perihelion approaches the critical regions. Similar arguments should be applicable to turbulence in other expanding astrophysical plasmas.</p>
Year of Publication
2019
Journal
The Astrophysical Journal
Volume
884
Number
Number of Pages
L57
Date Published
10/2019
URL
https://iopscience.iop.org/article/10.3847/2041-8213/ab4a82
DOI
10.3847/2041-8213/ab4a82