Properties of Magnetohydrodynamic Modes in Compressively Driven Plasma Turbulence

We study properties of magnetohydrodynamic (MHD) eigenmodes by decomposing the data of MHD simulations into linear MHD modes—namely, the Alfvén, slow magnetosonic, and fast magnetosonic modes. We drive turbulence with a mixture of solenoidal and compressive driving while varying the Alfvén Mach numb...

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Autores principales:	K. D. Makwana, Huirong Yan
Formato:	article
Lenguaje:	EN
Publicado:	American Physical Society 2020
Materias:	Physics QC1-999
Acceso en línea:	https://doaj.org/article/adabe491d620470e95bf411f88538981
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spelling	oai:doaj.org-article:adabe491d620470e95bf411f885389812021-12-02T11:14:43ZProperties of Magnetohydrodynamic Modes in Compressively Driven Plasma Turbulence10.1103/PhysRevX.10.0310212160-3308https://doaj.org/article/adabe491d620470e95bf411f885389812020-07-01T00:00:00Zhttp://doi.org/10.1103/PhysRevX.10.031021http://doi.org/10.1103/PhysRevX.10.031021https://doaj.org/toc/2160-3308We study properties of magnetohydrodynamic (MHD) eigenmodes by decomposing the data of MHD simulations into linear MHD modes—namely, the Alfvén, slow magnetosonic, and fast magnetosonic modes. We drive turbulence with a mixture of solenoidal and compressive driving while varying the Alfvén Mach number (M_{A}), plasma β, and the sonic Mach number from subsonic to transsonic. We find that the proportion of fast and slow modes in the mode mixture increases with increasing compressive forcing. This proportion of the magnetosonic modes can also become the dominant fraction in the mode mixture. The anisotropy of the modes is analyzed by means of their structure functions. The Alfvén-mode anisotropy is consistent with the Goldreich-Sridhar theory. We find a transition from weak to strong Alfvénic turbulence as we go from low to high M_{A}. The slow-mode properties are similar to the Alfvén mode. On the other hand, the isotropic nature of fast modes is verified in the cases where the fast mode is a significant fraction of the mode mixture. The fast-mode behavior does not show any transition in going from low to high M_{A}. We find indications that there is some interaction between the different modes, and the properties of the dominant mode can affect the properties of the weaker modes. This work identifies the conditions under which magnetosonic modes can be a major fraction of turbulent astrophysical plasmas, including the regime of weak turbulence. Important astrophysical implications for cosmic-ray transport and magnetic reconnection are discussed.K. D. MakwanaHuirong YanAmerican Physical SocietyarticlePhysicsQC1-999ENPhysical Review X, Vol 10, Iss 3, p 031021 (2020)
institution	DOAJ
collection	DOAJ
language	EN
topic	Physics QC1-999
spellingShingle	Physics QC1-999 K. D. Makwana Huirong Yan Properties of Magnetohydrodynamic Modes in Compressively Driven Plasma Turbulence
description	We study properties of magnetohydrodynamic (MHD) eigenmodes by decomposing the data of MHD simulations into linear MHD modes—namely, the Alfvén, slow magnetosonic, and fast magnetosonic modes. We drive turbulence with a mixture of solenoidal and compressive driving while varying the Alfvén Mach number (M_{A}), plasma β, and the sonic Mach number from subsonic to transsonic. We find that the proportion of fast and slow modes in the mode mixture increases with increasing compressive forcing. This proportion of the magnetosonic modes can also become the dominant fraction in the mode mixture. The anisotropy of the modes is analyzed by means of their structure functions. The Alfvén-mode anisotropy is consistent with the Goldreich-Sridhar theory. We find a transition from weak to strong Alfvénic turbulence as we go from low to high M_{A}. The slow-mode properties are similar to the Alfvén mode. On the other hand, the isotropic nature of fast modes is verified in the cases where the fast mode is a significant fraction of the mode mixture. The fast-mode behavior does not show any transition in going from low to high M_{A}. We find indications that there is some interaction between the different modes, and the properties of the dominant mode can affect the properties of the weaker modes. This work identifies the conditions under which magnetosonic modes can be a major fraction of turbulent astrophysical plasmas, including the regime of weak turbulence. Important astrophysical implications for cosmic-ray transport and magnetic reconnection are discussed.
format	article
author	K. D. Makwana Huirong Yan
author_facet	K. D. Makwana Huirong Yan
author_sort	K. D. Makwana
title	Properties of Magnetohydrodynamic Modes in Compressively Driven Plasma Turbulence
title_short	Properties of Magnetohydrodynamic Modes in Compressively Driven Plasma Turbulence
title_full	Properties of Magnetohydrodynamic Modes in Compressively Driven Plasma Turbulence
title_fullStr	Properties of Magnetohydrodynamic Modes in Compressively Driven Plasma Turbulence
title_full_unstemmed	Properties of Magnetohydrodynamic Modes in Compressively Driven Plasma Turbulence
title_sort	properties of magnetohydrodynamic modes in compressively driven plasma turbulence
publisher	American Physical Society
publishDate	2020
url	https://doaj.org/article/adabe491d620470e95bf411f88538981
work_keys_str_mv	AT kdmakwana propertiesofmagnetohydrodynamicmodesincompressivelydrivenplasmaturbulence AT huirongyan propertiesofmagnetohydrodynamicmodesincompressivelydrivenplasmaturbulence
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Properties of Magnetohydrodynamic Modes in Compressively Driven Plasma Turbulence

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