Ion-scale Turbulence and Energy Cascade Rate in the Solar Corona and Inner Heliosphere

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Autori principali: Kontar, Eduard P., Emslie, A. Gordon, Clarkson, Daniel L., Pitna, Alexander
Natura: Preprint
Pubblicazione: 2025
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author Kontar, Eduard P.
Emslie, A. Gordon
Clarkson, Daniel L.
Pitna, Alexander
author_facet Kontar, Eduard P.
Emslie, A. Gordon
Clarkson, Daniel L.
Pitna, Alexander
contents Plasma turbulence cascading from MHD to kinetic scales in the heliospheric plasma is believed to play a key role in coronal heating and fast solar wind acceleration, but the properties of the turbulence remain poorly constrained by observations. Here we compare the ion-scale density fluctuation levels inferred from the properties of solar radio bursts with the magnetic field fluctuation levels obtained through in-situ measurements in the inner heliosphere. We find that the observed magnetic and density fluctuation amplitudes are consistent with excitation by kinetic Alfvén waves and/or KAW structures over broad range of distances from the Sun. We then use the radio diagnostics and the KAW scenario to deduce the radial variation of magnetic fluctuation amplitudes in regions close to the Sun where in-situ measurements cannot be obtained. Further, we calculate the energy cascade rate (plasma heating rate) profile over a region that extends from the low corona ($\sim 0.1$~R$_\odot$) into the heliosphere (out to $\sim 1$~au), and compare it to the energy deposition rate required to drive the solar wind. The cascade rate agrees with the available in-situ measurements and also provides predictions closer than $\sim 10$~R$_\odot$ where in-situ approaches are not available. The results provide unique diagnostics of the ion-scale plasma turbulence amplitude and energy cascade rate spanning over three orders of magnitude in solar distance.
format Preprint
id arxiv_https___arxiv_org_abs_2509_17861
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Ion-scale Turbulence and Energy Cascade Rate in the Solar Corona and Inner Heliosphere
Kontar, Eduard P.
Emslie, A. Gordon
Clarkson, Daniel L.
Pitna, Alexander
Solar and Stellar Astrophysics
Plasma Physics
Plasma turbulence cascading from MHD to kinetic scales in the heliospheric plasma is believed to play a key role in coronal heating and fast solar wind acceleration, but the properties of the turbulence remain poorly constrained by observations. Here we compare the ion-scale density fluctuation levels inferred from the properties of solar radio bursts with the magnetic field fluctuation levels obtained through in-situ measurements in the inner heliosphere. We find that the observed magnetic and density fluctuation amplitudes are consistent with excitation by kinetic Alfvén waves and/or KAW structures over broad range of distances from the Sun. We then use the radio diagnostics and the KAW scenario to deduce the radial variation of magnetic fluctuation amplitudes in regions close to the Sun where in-situ measurements cannot be obtained. Further, we calculate the energy cascade rate (plasma heating rate) profile over a region that extends from the low corona ($\sim 0.1$~R$_\odot$) into the heliosphere (out to $\sim 1$~au), and compare it to the energy deposition rate required to drive the solar wind. The cascade rate agrees with the available in-situ measurements and also provides predictions closer than $\sim 10$~R$_\odot$ where in-situ approaches are not available. The results provide unique diagnostics of the ion-scale plasma turbulence amplitude and energy cascade rate spanning over three orders of magnitude in solar distance.
title Ion-scale Turbulence and Energy Cascade Rate in the Solar Corona and Inner Heliosphere
topic Solar and Stellar Astrophysics
Plasma Physics
url https://arxiv.org/abs/2509.17861