Ion versus Electron Heating in Compressively Driven Astrophysical Gyrokinetic Turbulence

The partition of irreversible heating between ions and electrons in compressively driven (but subsonic) collisionless turbulence is investigated by means of nonlinear hybrid gyrokinetic simulations. We derive a prescription for the ion-to-electron heating ratio Q_{i}/Q_{e} as a function of the compr...

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Autores principales:	Y. Kawazura, A. A. Schekochihin, M. Barnes, J. M. TenBarge, Y. Tong, K. G. Klein, W. Dorland
Formato:	article
Lenguaje:	EN
Publicado:	American Physical Society 2020
Materias:	Physics QC1-999
Acceso en línea:	https://doaj.org/article/736c06abfb494c089a3e8c3ae836f84b
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spelling	oai:doaj.org-article:736c06abfb494c089a3e8c3ae836f84b2021-12-02T14:23:38ZIon versus Electron Heating in Compressively Driven Astrophysical Gyrokinetic Turbulence10.1103/PhysRevX.10.0410502160-3308https://doaj.org/article/736c06abfb494c089a3e8c3ae836f84b2020-12-01T00:00:00Zhttp://doi.org/10.1103/PhysRevX.10.041050http://doi.org/10.1103/PhysRevX.10.041050https://doaj.org/toc/2160-3308The partition of irreversible heating between ions and electrons in compressively driven (but subsonic) collisionless turbulence is investigated by means of nonlinear hybrid gyrokinetic simulations. We derive a prescription for the ion-to-electron heating ratio Q_{i}/Q_{e} as a function of the compressive-to-Alfvénic driving power ratio P_{compr}/P_{AW}, of the ratio of ion thermal pressure to magnetic pressure β_{i}, and of the ratio of ion-to-electron background temperatures T_{i}/T_{e}. It is shown that Q_{i}/Q_{e} is an increasing function of P_{compr}/P_{AW}. When the compressive driving is sufficiently large, Q_{i}/Q_{e} approaches ≃P_{compr}/P_{AW}. This indicates that, in turbulence with large compressive fluctuations, the partition of heating is decided at the injection scales, rather than at kinetic scales. Analysis of phase-space spectra shows that the energy transfer from inertial-range compressive fluctuations to sub-Larmor-scale kinetic Alfvén waves is absent for both low and high β_{i}, meaning that the compressive driving is directly connected to the ion-entropy fluctuations, which are converted into ion thermal energy. This result suggests that preferential electron heating is a very special case requiring low β_{i} and no, or weak, compressive driving. Our heating prescription has wide-ranging applications, including to the solar wind and to hot accretion disks such as M87 and Sgr A*.Y. KawazuraA. A. SchekochihinM. BarnesJ. M. TenBargeY. TongK. G. KleinW. DorlandAmerican Physical SocietyarticlePhysicsQC1-999ENPhysical Review X, Vol 10, Iss 4, p 041050 (2020)
institution	DOAJ
collection	DOAJ
language	EN
topic	Physics QC1-999
spellingShingle	Physics QC1-999 Y. Kawazura A. A. Schekochihin M. Barnes J. M. TenBarge Y. Tong K. G. Klein W. Dorland Ion versus Electron Heating in Compressively Driven Astrophysical Gyrokinetic Turbulence
description	The partition of irreversible heating between ions and electrons in compressively driven (but subsonic) collisionless turbulence is investigated by means of nonlinear hybrid gyrokinetic simulations. We derive a prescription for the ion-to-electron heating ratio Q_{i}/Q_{e} as a function of the compressive-to-Alfvénic driving power ratio P_{compr}/P_{AW}, of the ratio of ion thermal pressure to magnetic pressure β_{i}, and of the ratio of ion-to-electron background temperatures T_{i}/T_{e}. It is shown that Q_{i}/Q_{e} is an increasing function of P_{compr}/P_{AW}. When the compressive driving is sufficiently large, Q_{i}/Q_{e} approaches ≃P_{compr}/P_{AW}. This indicates that, in turbulence with large compressive fluctuations, the partition of heating is decided at the injection scales, rather than at kinetic scales. Analysis of phase-space spectra shows that the energy transfer from inertial-range compressive fluctuations to sub-Larmor-scale kinetic Alfvén waves is absent for both low and high β_{i}, meaning that the compressive driving is directly connected to the ion-entropy fluctuations, which are converted into ion thermal energy. This result suggests that preferential electron heating is a very special case requiring low β_{i} and no, or weak, compressive driving. Our heating prescription has wide-ranging applications, including to the solar wind and to hot accretion disks such as M87 and Sgr A*.
format	article
author	Y. Kawazura A. A. Schekochihin M. Barnes J. M. TenBarge Y. Tong K. G. Klein W. Dorland
author_facet	Y. Kawazura A. A. Schekochihin M. Barnes J. M. TenBarge Y. Tong K. G. Klein W. Dorland
author_sort	Y. Kawazura
title	Ion versus Electron Heating in Compressively Driven Astrophysical Gyrokinetic Turbulence
title_short	Ion versus Electron Heating in Compressively Driven Astrophysical Gyrokinetic Turbulence
title_full	Ion versus Electron Heating in Compressively Driven Astrophysical Gyrokinetic Turbulence
title_fullStr	Ion versus Electron Heating in Compressively Driven Astrophysical Gyrokinetic Turbulence
title_full_unstemmed	Ion versus Electron Heating in Compressively Driven Astrophysical Gyrokinetic Turbulence
title_sort	ion versus electron heating in compressively driven astrophysical gyrokinetic turbulence
publisher	American Physical Society
publishDate	2020
url	https://doaj.org/article/736c06abfb494c089a3e8c3ae836f84b
work_keys_str_mv	AT ykawazura ionversuselectronheatingincompressivelydrivenastrophysicalgyrokineticturbulence AT aaschekochihin ionversuselectronheatingincompressivelydrivenastrophysicalgyrokineticturbulence AT mbarnes ionversuselectronheatingincompressivelydrivenastrophysicalgyrokineticturbulence AT jmtenbarge ionversuselectronheatingincompressivelydrivenastrophysicalgyrokineticturbulence AT ytong ionversuselectronheatingincompressivelydrivenastrophysicalgyrokineticturbulence AT kgklein ionversuselectronheatingincompressivelydrivenastrophysicalgyrokineticturbulence AT wdorland ionversuselectronheatingincompressivelydrivenastrophysicalgyrokineticturbulence
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Ion versus Electron Heating in Compressively Driven Astrophysical Gyrokinetic Turbulence

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