Energy Transport during 3D Small-scale Reconnection Driven by Anisotropic Plasma Turbulence

Abstract

Energy dissipation in collisionless plasmas is a long-standing fundamental physics problem. Although it is well known that magnetic reconnection and turbulence are coupled and transport energy from system-size scales to subproton scales, the details of the energy distribution and energy dissipation channels remain poorly understood. Especially, the energy transfer and transport associated with 3D small-scale reconnection that occurs as a consequence of a turbulent cascade is unknown. We use an explicit fully kinetic particle-in-cell code to simulate 3D small-scale magnetic reconnection events forming in anisotropic and decaying Alfvénic turbulence. We identify a highly dynamic and asymmetric reconnection event that involves two reconnecting flux ropes. We use a two-fluid approach based on the Boltzmann equation to study the spatial energy transfer associated with the reconnection event and compare the power density terms in the two-fluid energy equations with standard energy-based damping, heating, and dissipation proxies. Our findings suggest that the electron bulk flow transports thermal energy density more efficiently than kinetic energy density. Moreover, in our turbulent reconnection event, the energy density transfer is dominated by plasma compression. This is consistent with turbulent current sheets and turbulent reconnection events, but not with laminar reconnection.

Direct in-situ Estimates of Energy and Force Balance in Near Earth Collisionless Plasmas

“…It is expected that these terms are large in absolute value, and that it is their difference that accounts for bulk plasma acceleration, i.e., leading to an actual change in the time derivative of kinetic energy. Their results are in accordance with theoretical expectations as well as other works with different simulation approaches (e.g., Agudelo Rueda et al, 2022). The particularity of the work by Fadanelli et al (2021) is the measure of the energy terms in a point-by-point basis at the reconnection site and its close environment in the simulation domain instead of integrating the terms over the whole simulation domain (in which case the boundary conditions have a strong impact on the results).…”