Energy Conversion and Partition in Plasma Turbulence Driven by Magnetotail Reconnection

Abstract

A long-outstanding issue in fundamental plasma physics is how magnetic energy is finally dissipated in kinetic scale in the turbulent plasma. Based on the Magnetospheric Multiscale mission data in the plasma turbulence driven by magnetotail reconnection, we establish the quantitative relation between energy conversion ( J • E ; J is current density and E is electric field) and current density (J). The results show that the magnetic energy is primarily released in the perpendicular directions (up to 90%), in the region with current density less than 2.3 J rms, where J rms is the rms value of the total current density ∣ J ∣. In the relatively weak current region (<1.0 J rms), the ions get most of the released energy while the largely negative energy conversion rate of the electrons means a dynamo action. In the strong currents (>1.0 J rms), the ion energization was negligible and the electrons are significantly energized. Moreover, a linearly increasing relationship was established between ∣ J • E ∣ and J . The observations indicate that ions overall dominate energy conversion in turbulence, but the electron dynamics are crucial for energy conversion in intense currents and the turbulence evolution.

Three‐Dimensional Particle‐In‐Cell Simulations of Electron‐Only Magnetic Reconnection Between Laser‐Produced Plasma Bubbles

“…Next we investigate the energy conversion during electron‐only reconnection, which is governed by the Poynting theorem (Birn & Hesse, 2010) $$\frac{\partial }{\partial t}\left(\frac{{{\epsilon}}_{0}{E}^{2}}{2}\right)+\frac{\partial }{\partial t}\left(\frac{{B}^{2}}{2{\mu }_{0}}\right)+\nabla \cdot \vec{S}=-\vec{J}\cdot \vec{E}$$, where $$\vec{S}$$ is the Poynting flux $$\vec{S}=\vec{E}\times \vec{B}/{\mu }_{0}$$. The energy conversion term $$\vec{J}\cdot \vec{E}$$, representing the energy conversion between electromagnetic energy and plasma kinetic energy, has been widely employed in previous studies concerning energy transfer in magnetic reconnection (e.g., X. Li et al., 2022; Wang et al., 2018, and others). According to the Poynting theorem, as $$\vec{J}\cdot \vec{E}$$ is positive, energy is transferred from the electromagnetic fields to the particles.…”

Suprathermal Ions Observed Inside a Magnetic Flux Rope in the Earth's Magnetotail

“…Namely, the energy conversion was occurring therein. The negative J · E ’ indicates a dynamo process therein, that is, the electron kinetic energy is conversed into magnetic free energy (Li et al., 2022). Alternatively, the negative J · E ’ could be caused also by magnetic reconnection, since it can be generated in the region surrounding the electron diffusion region (Karimabadi et al., 2007; R Wang et al., 2017a; Zenitani et al., 2011).…”

Kinetic Scale Magnetic Reconnection with a Turbulent Forcing: Particle-in-cell Simulations

“…The laminar Hall reconnection picture derived from numerous spacecraft observations (e.g., Nagai et al 2001;Borg et al 2005;Eastwood et al 2010) and numerical simulations (e.g., Pritchett 2001;Lu et al 2010) can well describe kinetic scale fast reconnection. Nevertheless, kinetic scale turbulent magnetic reconnection is still common in space, as shown by many in situ spacecraft observations in Earthʼs magnetosphere (Eastwood et al 2009;Huang et al 2012;Osman et al 2015;Zhou et al 2021;Ergun et al 2022;Jin et al 2022;Li et al 2022aLi et al , 2022b and the solar wind (Vörös et al 2014;Wang et al 2022).…”