Scaling of Particle Heating in Shocks and Magnetic Reconnection

Fuente: arXiv
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Main Authors: Oka, Mitsuo, Phan, Tai D., Øieroset, Marit, Gershman, Daniel J., Torbert, Roy B., Burch, James L., Angelopoulos, Vassilis
Format: Preprint
Published: 2025
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author Oka, Mitsuo
Phan, Tai D.
Øieroset, Marit
Gershman, Daniel J.
Torbert, Roy B.
Burch, James L.
Angelopoulos, Vassilis
author_facet Oka, Mitsuo
Phan, Tai D.
Øieroset, Marit
Gershman, Daniel J.
Torbert, Roy B.
Burch, James L.
Angelopoulos, Vassilis
contents Particles are heated efficiently through energy conversion processes such as shocks and magnetic reconnection in collisionless plasma environments. While empirical scaling laws for the temperature increase have been obtained, the precise mechanism of energy partition between ions and electrons remains unclear. Here we show, based on coupled theoretical and observational scaling analyses, that the temperature increase, $ΔT$, depends linearly on three factors: the available magnetic energy per particle, the Alfvén Mach number (or reconnection rate), and the characteristic spatial scale $L$. Based on statistical datasets obtained from Earth's plasma environment, we find that $L$ is on the order of (1) the ion gyro-radius for ion heating at shocks, (2) the ion inertial length for ion heating in magnetic reconnection, and (3) the hybrid inertial length for electron heating in both shocks and magnetic reconnection. With these scales, we derive the ion-to-electron ratios of temperature increase as $ΔT_{\rm i}/ΔT_{\rm e} = (3β_{\rm i}/2)^{1/2}(m_{\rm i}/m_{\rm e})^{1/4}$ for shocks and $ΔT_{\rm i}/ΔT_{\rm e} = (m_{\rm i}/m_{\rm e})^{1/4}$ for magnetic reconnection, where $β_{\rm i}$ is the ion plasma beta, and $m_{\rm i}$ and $ m_{\rm e}$ are the ion and electron particle masses, respectively. We anticipate that this study will serve as a starting point for a better understanding of particle heating in space plasmas, enabling more sophisticated modeling of its scaling and universality.
format Preprint
id arxiv_https___arxiv_org_abs_2503_14823
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Scaling of Particle Heating in Shocks and Magnetic Reconnection
Oka, Mitsuo
Phan, Tai D.
Øieroset, Marit
Gershman, Daniel J.
Torbert, Roy B.
Burch, James L.
Angelopoulos, Vassilis
Plasma Physics
Space Physics
Particles are heated efficiently through energy conversion processes such as shocks and magnetic reconnection in collisionless plasma environments. While empirical scaling laws for the temperature increase have been obtained, the precise mechanism of energy partition between ions and electrons remains unclear. Here we show, based on coupled theoretical and observational scaling analyses, that the temperature increase, $ΔT$, depends linearly on three factors: the available magnetic energy per particle, the Alfvén Mach number (or reconnection rate), and the characteristic spatial scale $L$. Based on statistical datasets obtained from Earth's plasma environment, we find that $L$ is on the order of (1) the ion gyro-radius for ion heating at shocks, (2) the ion inertial length for ion heating in magnetic reconnection, and (3) the hybrid inertial length for electron heating in both shocks and magnetic reconnection. With these scales, we derive the ion-to-electron ratios of temperature increase as $ΔT_{\rm i}/ΔT_{\rm e} = (3β_{\rm i}/2)^{1/2}(m_{\rm i}/m_{\rm e})^{1/4}$ for shocks and $ΔT_{\rm i}/ΔT_{\rm e} = (m_{\rm i}/m_{\rm e})^{1/4}$ for magnetic reconnection, where $β_{\rm i}$ is the ion plasma beta, and $m_{\rm i}$ and $ m_{\rm e}$ are the ion and electron particle masses, respectively. We anticipate that this study will serve as a starting point for a better understanding of particle heating in space plasmas, enabling more sophisticated modeling of its scaling and universality.
title Scaling of Particle Heating in Shocks and Magnetic Reconnection
topic Plasma Physics
Space Physics
url https://arxiv.org/abs/2503.14823