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2020
Authors: Huang S. Y., Zhang J., Sahraoui F., He J. S., Yuan Z. G., et al.
Title: Kinetic Scale Slow Solar Wind Turbulence in the Inner Heliosphere: Coexistence of Kinetic Alfvén Waves and Alfvén Ion Cyclotron Waves
Abstract:

The nature of the plasma wave modes around the ion kinetic scales in highly Alfvénic slow solar wind turbulence is investigated using data from the NASA’s Parker Solar Probe taken in the inner heliosphere, at 0.18 au from the Sun. The joint distribution of the normalized reduced magnetic helicity σmRB, τ) is obtained, where θRB is the angle between the local mean magnetic field and the radial direction and τ is the temporal scale. Two populations around ion scales are identified: the first population has σmRB, τ) < 0 for frequencies (in the spacecraft frame) ranging from 2.1 to 26 Hz for 60° < θRB < 130°, corresponding to kinetic Alfvén waves (KAWs), and the second population has σmDate: 07/2020 Publisher: The Astrophysical Journal Pages: L3 DOI: 10.3847/2041-8213/ab9abb Available at: https://iopscience.iop.org/article/10.3847/2041-8213/ab9abbhttps://iopscience.iop.org/article/10.3847/2041-8213/ab9abb/
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Authors: Vech Daniel, Kasper Justin C., Klein Kristopher G., Huang Jia, Stevens Michael L., et al.
Title: Kinetic-scale Spectral Features of Cross Helicity and Residual Energy in the Inner Heliosphere
Abstract:

In this work, we present the first results from the flux angle (FA) operation mode of the Faraday Cup instrument on board the Parker Solar Probe (PSP). The FA mode allows rapid measurements of phase space density fluctuations close to the peak of the proton velocity distribution function with a cadence of 293 Hz. This approach provides an invaluable tool for understanding kinetic-scale turbulence in the solar wind and solar corona. We describe a technique to convert the phase space density fluctuations into vector velocity components and compute several turbulence parameters, such as spectral index, residual energy, and cross helicity during two intervals when the FA mode was used in PSP’s first encounter at 0.174 au distance from the Sun.


Date: 02/2020 Publisher: The Astrophysical Journal Supplement Series Pages: 52 DOI: 10.3847/1538-4365/ab60a2 Available at: https://iopscience.iop.org/article/10.3847/1538-4365/ab60a2
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2015
Authors: Isenberg Philip A., and Vasquez Bernard J.
Title: KINETIC EVOLUTION OF CORONAL HOLE PROTONS BY IMBALANCED ION-CYCLOTRON WAVES: IMPLICATIONS FOR MEASUREMENTS BY SOLAR PROBE PLUS
Abstract:

We extend the kinetic guiding-center model of collisionless coronal hole protons presented in Isenberg & Vasquez to consider driving by imbalanced spectra of obliquely propagating ion-cyclotron waves. These waves are assumed to be a small by-product of the imbalanced turbulent cascade to high perpendicular wavenumber, and their total intensity is taken to be 1% of the total fluctuation energy. We also extend the kinetic solutions for the proton distribution function in the resulting fast solar wind to heliocentric distances of 20 solar radii, which will be attainable by the Solar Probe Plus spacecraft. We consider three ratios of outward-propagating to inward-propagating resonant intensities: 1, 4, and 9. The self-consistent bulk flow speed reaches fast solar wind values in all case. . .
Date: 08/2015 Publisher: The Astrophysical Journal Pages: 119 DOI: 10.1088/0004-637X/808/2/119 Available at: http://stacks.iop.org/0004-637X/808/i=2/a=119?key=crossref.961efccaa84816c8b4c9e041f523e07f
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