Energy partition in collisionless counterstreaming plasmas

Fuente: arXiv
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Autores principales: Marret, Alexis, Fiuza, Frederico
Formato: Preprint
Publicado: 2026
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author Marret, Alexis
Fiuza, Frederico
author_facet Marret, Alexis
Fiuza, Frederico
contents Fast, counter-streaming plasma outflows drive magnetic field amplification, plasma heating, and particle acceleration in numerous astrophysical environments, from supernova remnant shocks to active galactic nuclei jets. Understanding how, in the absence of Coulomb collisions, energy is redistributed between the different plasma species remains a fundamental open question. We use 3D fully-kinetic simulations to investigate energy partition in weakly magnetized counter-propagating plasmas. Our results reveal a complex interplay between different processes, where at early times the Weibel instability drives a first stage of magnetic field amplification and at late times the kinking of current filaments drives a second amplification stage via a dynamo-type mechanism. Electrons are heated primarily during the latter phase through magnetic pumping. By the time the flows thermalize, we observe that the final temperature ratio $T_e/T_i$ and energy partition depend on the ion-to-electron mass ratio. For electron-proton flows, the electron thermal energy only reaches up to a few percent of the initial ion kinetic energy.
format Preprint
id arxiv_https___arxiv_org_abs_2601_18988
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Energy partition in collisionless counterstreaming plasmas
Marret, Alexis
Fiuza, Frederico
Plasma Physics
High Energy Astrophysical Phenomena
Fast, counter-streaming plasma outflows drive magnetic field amplification, plasma heating, and particle acceleration in numerous astrophysical environments, from supernova remnant shocks to active galactic nuclei jets. Understanding how, in the absence of Coulomb collisions, energy is redistributed between the different plasma species remains a fundamental open question. We use 3D fully-kinetic simulations to investigate energy partition in weakly magnetized counter-propagating plasmas. Our results reveal a complex interplay between different processes, where at early times the Weibel instability drives a first stage of magnetic field amplification and at late times the kinking of current filaments drives a second amplification stage via a dynamo-type mechanism. Electrons are heated primarily during the latter phase through magnetic pumping. By the time the flows thermalize, we observe that the final temperature ratio $T_e/T_i$ and energy partition depend on the ion-to-electron mass ratio. For electron-proton flows, the electron thermal energy only reaches up to a few percent of the initial ion kinetic energy.
title Energy partition in collisionless counterstreaming plasmas
topic Plasma Physics
High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2601.18988