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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Generation and effects of electromotive force in turbulent stochastic reconnection

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Author(s):
Nowak, Natalia [1] ; Kowal, Grzegorz [2] ; Falceta-Goncalves, Diego A. [2]
Total Authors: 3
Affiliation:
[1] Jagiellonian Univ, Astron Observ, Ul Orla 171, PL-30244 Krakow - Poland
[2] Univ Sao Paulo, Escola Artes Ciencias & Humanidades, Av Arlindo Bettio 1000, BR-03828000 Sao Paulo - Brazil
Total Affiliations: 2
Document type: Journal article
Source: Physics of Plasmas; v. 28, n. 6 JUN 2021.
Web of Science Citations: 0
Abstract

Reconnection is an important process that rules dissipation and diffusion of magnetic energy in plasmas. It is already clear that its rate is enhanced by turbulence and that reconnection itself may increase its stochasticity, but the main mechanism that connects these two effects is still not completely understood. The aim of this work is to identify, from the terms of the electromotive force, the dominant physical process responsible for enhancing the reconnection rate in turbulent plasmas. We employ full three-dimensional numerical simulations of turbulence driven by stochastic reconnection and estimate the production and dissipation of turbulent energy and cross-helicity, the amount of produced residual helicity, and determine the relation between these quantities and the reconnection rate. We observe the development of the electromotive force in the studied models with plasma-beta = 0.1 - 2 and the Lundquist number S = 10(-5) - 10(-4). The turbulent energy and residual helicity develop in the large-scale current sheet, with the latter decreasing the effects of turbulent magnetic diffusion. We demonstrate that the stochastic reconnection, apart from the turbulence, can produce a finite value of cross-helicity (the magnitude of the turbulent cross-helicity to energy of the order of 10(-5) - 10(-3)). Under this situation, the cross-helicity to turbulent energy ratio, however, has no correlation with the reconnection rate. We show that in this range of magnitude, the cross-helicity is not a necessary condition for fast reconnection to occur. The results suggest that cross-helicity is inherent to turbulent fields, but the reconnection rate enhancement is possibly caused by the effects of magnetic turbulent diffusion and controlled by the residual helicity. Published under an exclusive license by AIP Publishing. (AU)

FAPESP's process: 13/10559-5 - Investigation of high energy and plasma astrophysics phenomena: theory, numerical simulations, observations, and instrument development for the Cherenkov Telescope Array (CTA)
Grantee:Elisabete Maria de Gouveia Dal Pino
Support type: Research Projects - Thematic Grants
FAPESP's process: 19/03301-8 - Observation and models of solar and stellar active regions at radio wavelengths (mm/sub-mm)
Grantee:Caius Lucius Selhorst
Support type: Regular Research Grants