Magnetic Helicity Associated with the Proton Temperature Anisotropy Instabilities in the Presence of an Imbalanced Solar Wind Turbulence
Some of the most common processes in the solar wind, such as turbulence and wave generation by instabilities, are associated with spectral magnetic helicity. Therefore, the helicity is a convenient tool to investigate these processes. We use three-dimensional nonlinear kinetic simulations with parti...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
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IOP Publishing
2023-01-01
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| Series: | The Astrophysical Journal |
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| Online Access: | https://doi.org/10.3847/1538-4357/acdb66 |
| _version_ | 1827826072242094080 |
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| author | S. A. Markovskii Bernard J. Vasquez |
| author_facet | S. A. Markovskii Bernard J. Vasquez |
| author_sort | S. A. Markovskii |
| collection | DOAJ |
| description | Some of the most common processes in the solar wind, such as turbulence and wave generation by instabilities, are associated with spectral magnetic helicity. Therefore, the helicity is a convenient tool to investigate these processes. We use three-dimensional nonlinear kinetic simulations with particle ions and fluid electrons to analyze the magnetic helicity produced by proton temperature anisotropy instabilities coexisting with an ambient turbulence. The symmetry of the unstable system is violated by alpha-particle streaming with respect to protons along the mean magnetic field. At the same time, the turbulent fluctuations are also imbalanced by a nonzero cross-helicity. We show that in the nonlinear phase of the instability the resulting helicity structure is different from the prediction of the linear theory. In particular, it contains sign reversals and multiple domains of nonzero helicity. The turbulence generates its own magnetic helicity signature, which extends over a wide range of angles around the direction perpendicular to the mean magnetic field, and can have a sign the same as or opposite to that of the instability. These findings are consistent with the observed helicity spectra in the solar wind. |
| first_indexed | 2024-03-12T02:59:27Z |
| format | Article |
| id | doaj.art-c863cebd33694f10b004f41eb5eef350 |
| institution | Directory Open Access Journal |
| issn | 1538-4357 |
| language | English |
| last_indexed | 2024-03-12T02:59:27Z |
| publishDate | 2023-01-01 |
| publisher | IOP Publishing |
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| series | The Astrophysical Journal |
| spelling | doaj.art-c863cebd33694f10b004f41eb5eef3502023-09-03T14:54:06ZengIOP PublishingThe Astrophysical Journal1538-43572023-01-0195211610.3847/1538-4357/acdb66Magnetic Helicity Associated with the Proton Temperature Anisotropy Instabilities in the Presence of an Imbalanced Solar Wind TurbulenceS. A. Markovskii0Bernard J. Vasquez1https://orcid.org/0000-0001-8593-7289Space Science Center, University of New Hampshire , Durham, NH 03824, USA ; sergei.markovskii@unh.edu, bernie.vasquez@unh.eduSpace Science Center, University of New Hampshire , Durham, NH 03824, USA ; sergei.markovskii@unh.edu, bernie.vasquez@unh.eduSome of the most common processes in the solar wind, such as turbulence and wave generation by instabilities, are associated with spectral magnetic helicity. Therefore, the helicity is a convenient tool to investigate these processes. We use three-dimensional nonlinear kinetic simulations with particle ions and fluid electrons to analyze the magnetic helicity produced by proton temperature anisotropy instabilities coexisting with an ambient turbulence. The symmetry of the unstable system is violated by alpha-particle streaming with respect to protons along the mean magnetic field. At the same time, the turbulent fluctuations are also imbalanced by a nonzero cross-helicity. We show that in the nonlinear phase of the instability the resulting helicity structure is different from the prediction of the linear theory. In particular, it contains sign reversals and multiple domains of nonzero helicity. The turbulence generates its own magnetic helicity signature, which extends over a wide range of angles around the direction perpendicular to the mean magnetic field, and can have a sign the same as or opposite to that of the instability. These findings are consistent with the observed helicity spectra in the solar wind.https://doi.org/10.3847/1538-4357/acdb66Space plasmasInterplanetary turbulenceSolar wind |
| spellingShingle | S. A. Markovskii Bernard J. Vasquez Magnetic Helicity Associated with the Proton Temperature Anisotropy Instabilities in the Presence of an Imbalanced Solar Wind Turbulence The Astrophysical Journal Space plasmas Interplanetary turbulence Solar wind |
| title | Magnetic Helicity Associated with the Proton Temperature Anisotropy Instabilities in the Presence of an Imbalanced Solar Wind Turbulence |
| title_full | Magnetic Helicity Associated with the Proton Temperature Anisotropy Instabilities in the Presence of an Imbalanced Solar Wind Turbulence |
| title_fullStr | Magnetic Helicity Associated with the Proton Temperature Anisotropy Instabilities in the Presence of an Imbalanced Solar Wind Turbulence |
| title_full_unstemmed | Magnetic Helicity Associated with the Proton Temperature Anisotropy Instabilities in the Presence of an Imbalanced Solar Wind Turbulence |
| title_short | Magnetic Helicity Associated with the Proton Temperature Anisotropy Instabilities in the Presence of an Imbalanced Solar Wind Turbulence |
| title_sort | magnetic helicity associated with the proton temperature anisotropy instabilities in the presence of an imbalanced solar wind turbulence |
| topic | Space plasmas Interplanetary turbulence Solar wind |
| url | https://doi.org/10.3847/1538-4357/acdb66 |
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