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Anisotropic Magnetic Turbulence in the Inner HeliosphereRadial Evolution of Distributions Observed by Parker Solar Probe
Author  Chhiber, Rohit; 
Keywords  Parker Data Used; Solar wind; interplanetary magnetic fields; interplanetary turbulence; 1534; 824; 830; Astrophysics  Solar and Stellar Astrophysics; Physics  Plasma Physics; Physics  Space Physics 
Abstract  Observations from Parker Solar Probe s first five orbits are used to investigate the helioradial evolution of probability density functions (pdfs) of fluctuations of magneticfield components between \raisebox0.5ex\textasciitilde28 and 200 R $_\ensuremath\odot$. Transformation of the magneticfield vector to a local meanfield coordinate system permits examination of anisotropy relative to the mean magneticfield direction. Attention is given to effects of averaginginterval size. It is found that pdfs of the perpendicular fluctuations are well approximated by a Gaussian function, with the parallel fluctuations less so: kurtoses of the latter are generally larger than 10, and their pdfs indicate increasing skewness with decreasing distance r from the Sun, with the latter observation possibly explained by the increasing Alfv\ enicity of the fluctuations. The ratio of perpendicular to parallel variances is greater than unity; this variance anisotropy becomes stronger with decreasing r. The ratio of the total rms fluctuation strength to the meanfield magnitude decreases with decreasing r, with a value \raisebox0.5ex\textasciitilde0.8 near 1 au and \raisebox0.5ex\textasciitilde0.5 at 0.14 au; the ratio is well approximated by an r $^1/4$ power law. These findings improve our understanding of the radial evolution of turbulence in the solar wind, and have implications for related phenomena such as energeticparticle transport in the inner heliosphere. 
Year of Publication  2022 
Journal  \apj 
Volume  939 
Number of Pages  33 
Section  
Date Published  nov 
ISBN  
URL  
DOI  10.3847/15384357/ac9386 