Abstract
Context. In space and astrophysical plasmas, turbulence leads to the development of coherent structures characterized by a strong current density and important magnetic shears. Aims. Using hybrid-kinetic simulations of turbulence (3D with different energy injection scales), we investigate the development of these coherent structures and characterize their shape. Methods. First, we present different methods to estimate the overall shape of the 3D structure using local measurements, foreseeing an application on satellite data. Then we study the local magnetic configuration inside and outside current peak regions, comparing the statistics in the two cases. Last, we compare the statistical properties of the local configuration obtained in simulations with the ones obtained analyzing an MMS (Magnetospheric MultiScale mission) dataset having similar plasma parameters. Results. Thanks to our analysis, (1) we validate the possibility of studying the overall shape of 3D structures using local methods, (2) we provide an overview of a local magnetic configuration emerging in different turbulent regimes, (3) we show that our 3D-3V simulations can reproduce the structures that emerge in MMS data for the periods considered.
Highlights
Turbulent, magnetized plasmas permeate a wide range of space and astrophysical environments, and plasma turbulence naturally develops coherent structures characterized by a high current density and strong magnetic shear
While such a characterization can be achieved by a number of procedures, on we focus on the magnetic configuration analysis (MCA) method proposed by Fadanelli et al (2019)
In order to be directly comparable with our simulations, a three-step selection on the abovementioned Magnetospheric Multiscale (MMS) data has been applied so that the magnetic configuration analysis has been performed on only those data points for which (i) the computation of N is precise enough that at least two eigenvalues are well determined, (ii) β ∈ [0.3, 3], and (iii) the resolution attained by MMS data is comparable with that of the numerical simulations
Summary
Turbulent, magnetized plasmas permeate a wide range of space and astrophysical environments, and plasma turbulence naturally develops coherent structures characterized by a high current density and strong magnetic shear. In order to determine the physical behavior of coherent current structures, it is of foremost importance to understand how they manifest within the (turbulent) magnetic-field dynamics. This task can be separated into two main inquiries. (2) On the other hand, it is of key importance to understand how (and if) local magneticfield configurations within the abovementioned current structures are systematically different from the magnetic configuration that belongs to the rest of the (turbulent) environment While such a characterization can be achieved by a number of procedures, on we focus on the magnetic configuration analysis (MCA) method proposed by Fadanelli et al (2019). Contrary to measures of current structure geometry, the analysis of magnetic configurations can
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