Subproton-scale Intermittency in Near-Sun Solar Wind Turbulence Observed by the Parker Solar Probe

Abstract

High time-resolution solar wind magnetic field data is employed to study statistics describing intermittency near the first perihelion (~35.6 Rs) of the Parker Solar Probe mission. A merged dataset employing two instruments on the FIELDS suite enables broadband estimation of higher order moments of magnetic field increments, with five orders established with reliable accuracy. The duration, cadence, and low noise level of the data permit evaluation of scale dependence of the observed intermittency from the inertial range to deep subproton scales. The results support multifractal scaling in the inertial range, and monofractal but non-Gaussian scaling in the subproton range, thus clarifying suggestions based on data near Earth that had remained ambiguous due to possible interference of the terrestrial foreshock. The physics of the transition to monofractality remains unclear but we suggest that it is due to a scale-invariant population of current sheets between ion and electron inertial scales; the previous suggestion of incoherent kinetic-scale wave activity is disfavored as it presumably leads to re-Gaussianization which is not observed.

Accepted for publication in The Astrophysical Journal Letters

References in corpus (7)

• The Evolution and Role of Solar Wind Turbulence in the Inner Heliosphere
• Recent progress in astrophysical plasma turbulence from solar wind observations
• Switchbacks in the near-Sun magnetic field: long memory and impact on the turbulence cascade
• The Solar Probe Cup on Parker Solar Probe
• Intermittency of Solar Wind Density Fluctuations From Ion to Electron Scales
• Contextual Predictions for Parker Solar Probe II: Turbulence Properties and Taylor Hypothesis
• Clustering of Intermittent Magnetic and Flow Structures near Parker Solar Probe's First Perihelion -- A Partial-Variance-of-Increments Analysis

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• Kinetic-scale current sheets in near-Sun solar wind: properties, scale-dependent features and reconnection onset
• The radial variation of the solar wind turbulence spectra near the kinetic break scale from Parker Solar Probe measurements
• An Extended and Fragmented Alfvén Zone in the Young Solar Wind
• Magnetic field intermittency in the solar wind: PSP and SolO observations ranging from the Alfven region out to 1 AU
• Markovian Features of the Solar Wind at Sub-Proton Scales
• Reconciling Parker Solar Probe observations and magnetohydrodynamic theory
• On the scaling and anisotropy of two subranges in the inertial range of solar wind turbulence