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The topology of the magnetic and velocity fields at the kinetic scales are investigated in the context of nearly incompressible magnetosheath plasma turbulence. Using the unprecedented high‐resolution data from the Magnetospheric MultiScale mission, the joint probability distribution functions of geometrical invariants characterizing the magnetic and velocity fields gradient tensor at the kinetic scales are computed. The topological features of the magnetic and velocity field gradient tensors and their symmetric component tensors present axisymmetric distribution patterns, indicating that the structure of the plasma turbulence at the kinetic scales are different from those in hydrodynamic and magnetohydrodynamic turbulence. Moreover, a strong correlation between the straining and rotational parts of the magnetic and velocity field gradient tensors was found, which manifests the dominance of sheet‐like structures at the kinetic‐scales dissipation in incompressible plasma turbulence. Plain Language Summary: The terrestrial magnetosheath provides an excellent laboratory to study space plasma turbulence. Thanks to the unprecedented high time resolution data of the Magnetospheric Multiscale mission, the kinetic‐scales structures and dynamic of incompressible magnetosheath plasma turbulence can be investigated. By means of a universal topological classification method in fluid dynamics area, we construct the topological features of both magnetic and velocity field in incompressible plasma turbulence at dissipation scales. Our results show that the distribution of velocity‐field topological structures is different from the other turbulence system, such as hydrodynamic and magnetohydrodynamic turbulence. In addition, we verify that the sheet‐like structures dominate the kinetic‐scales dissipation in the incompressible plasma turbulence. Key Points: The kinetic‐scales topological features in incompressible magnetosheath plasma turbulence are investigatedDistribution patterns different from hydrodynamic and magnetohydrodynamic turbulence of velocity‐field topological characteristics are identifiedSheet‐like structures dominate dissipation‐scale dynamics in the incompressible plasma turbulence [ABSTRACT FROM AUTHOR]

We present a novel technique to analyze VDF, which allows to capture their fine structure including wave‐particles resonances. By applying the technique to magnetospheric multiscale (MMS) data, the simultaneous observation of characteristic three‐dimensional (3‐D) signatures in the electron velocity distribution function (VDF) and intense quasi‐monochromatic waves in the terrestrial magnetosheath is investigated. The intense wave packets are characterized and modeled analytically as quasi‐parallel circularly polarized whistler waves and applied to a test‐particle simulation in view of gaining insight into the signature of the wave‐particle resonances in velocity space. Both the Landau and the cyclotron resonances were evidenced in the test‐particle simulations. The location and general shape of the test‐particle signatures do account for the observations, but the finer details, such as the symmetry of the observed signatures, are not matched, indicating either the limits of the test‐particle approach or a more fundamental physical mechanism not yet grasped. Finally, it is shown that the energization of the electrons in this precise resonance case cannot be diagnosed using the moments of the distribution function, as done with the classical E · J "dissipation" estimate. Key Points: Characteristic double‐branch signatures in the electron velocity distribution function are observed simultaneously with a whistler waveThe wave, applied to test‐particles, produces signatures in the VDF through Landau and cyclotron resonancesThis resonant wave‐particle interaction cannot be diagnosed in the magnetospheric multiscale observations through the dissipative E · J term [ABSTRACT FROM AUTHOR]

An ion‐scale flux rope (FR), embedded in a high‐speed electron flow (possibly an electron vortex), is investigated in the magnetotail using observations from the Magnetospheric Multiscale (MMS) spacecraft. Intense electric field and current and abundant waves are observed in the exterior and interior regions of the FR. Comparable parallel and perpendicular currents in the interior region imply that the FR has a non‐force‐free configuration. Electron demagnetization occurs in some subregions of the FR. It is surprising that strong dissipation (J × E' up to 2,000 pW/m3) occurs in the center of the FR without signatures of secondary reconnection or coalescence of two FRs, implying that FR may provide another important channel for energy dissipation in space plasmas. These features indicate that the observed FR is still highly dynamical, and hosts multiscale coupling processes, even though the FR has a very large scale and is far away from the reconnection site. Plain Language Summary: Flux ropes, 3‐D helical magnetic structures, in which magnetic field lines twist with each other, play an important role in the macroscopic and microscopic physical process during magnetic reconnection. Most of previous studies focused on the flux ropes in the reconnection region. However, some physical process inside macroscopic flux ropes far away from the reconnection site in the magnetotail is still unclear due to the lack of high time resolution data. In this letter, thanks to the unprecedented high time resolution data of the Magnetospheric Multiscale (MMS) mission, we report an ion‐scale flux rope and study its dynamics. Our observations demonstrate that the observed flux rope is still highly dynamical, and hosting multiscale coupling processes and strong energy dissipation, even though the flux rope has very large scale and is far away from the reconnection site. Key Points: An ion‐scale flux rope, embedded in possible electron vortex, is investigated in the magnetotail in detailsElectron demagnetization occurs in some subregions of the flux rope, and abundant waves are detected in the exterior and interior regionsStrong dissipation occurs in the flux rope, implying that flux rope provides another important channel for energy dissipation in space plasma [ABSTRACT FROM AUTHOR]

Using spatio-temporal spectra, we show direct evidence of excitation of magnetosonic and Alfvén waves in three-dimensional compressible magnetohydrodynamic turbulence at small Mach numbers. For the plasma pressure dominated regime, or the high β regime (with β the ratio between fluid and magnetic pressure), and for the magnetic pressure dominated regime, or the low β regime, we study magnetic field fluctuations parallel and perpendicular to a guide magnetic field B0. In the low β case, we find excitation of compressible and incompressible fluctuations, with a transfer of energy towards Alfvénic modes and to a lesser extent towards magnetosonic modes. In particular, we find signatures of the presence of fast magnetosonic waves in a scenario compatible with that of weak turbulence. In the high β case, fast and slow magnetosonic waves are present, with no clear trace of Alfvén waves, and a significant part of the energy is carried by two-dimensional turbulent eddies. [ABSTRACT FROM AUTHOR]

Using the four Cluster spacecraft, we have determined the three-dimensional wave-vector spectra of fluctuating magnetic fields in the solar wind. Three different solar wind intervals of Cluster data are investigated for this purpose, representing three different spatial scales: 10 000 km, 1000 km, and 100 km. The spectra are determined using the wave telescope technique (k-filtering technique) without assuming the validity of Taylor's frozen-in-flow hypothesis nor are any assumptions made as to the symmetry properties of the fluctuations. We find that the spectra are anisotropic on all the three scales and the power is extended primarily in the directions perpendicular to the mean magnetic field, as might be expected of two-dimensional turbulence, however, the analyzed fluctuations are not axisymmetric. The lack of axisymmetry invalidates some earlier techniques using single spacecraft observations that were used to estimate the percentage of magnetic energy residing in quasitwo- dimensional power. However, the dominance of twodimensional turbulence is consistent with the relatively long mean free paths of cosmic rays in observed in the heliosphere. On the other hand, the spectra also exhibit secondary extended structures oblique from the mean magnetic field direction. We discuss possible origins of anisotropy and asymmetry of solar wind turbulence spectra. [ABSTRACT FROM AUTHOR]

Discusses the formation of magnetosheath between the bow shock and the magnetopause. Contribution of plasma from magnetosphere; Observation of magnetosheath plasma parameters; Nature of the bow shock on the orientation of the interplanetary magnetic field with respect to the local bow shock normal.

The exact law for fully developed homogeneous compressible magnetohydrodynamics (CMHD) turbulence is derived. For an isothermal plasma, without the assumption of isotropy, the exact law is expressed as a function of the plasma velocity field, the compressible Alfvén velocity, and the scalar density, instead of the Elsasser variables used in previous works. The theoretical results show four different types of terms that are involved in the nonlinear cascade of the total energy in the inertial range. Each category is examined in detail, in particular, those that can be written either as source or flux terms. Finally, the role of the background magnetic field B0 is highlighted and a comparison with the incompressible MHD (IMHD) model is discussed. This point is particularly important when testing this exact law on numerical simulations and in situ observations in space plasmas. [ABSTRACT FROM AUTHOR]

The environmental and economic impacts linked with solar systems are largely based on discharges of slurry generated during the various stages of sawing and cutting ingots. These discharges into the environment are subject to the general regulations on hazardous and special industrial waste disposal. Therefore, they should not be abandoned or burned in open air. The cutting of Silicon ingots leads to the production of Silicon wafers additional costs, losing more than 30% of Silicon material. Abrasive grains (Silicon Carbide) trapped between the wire and the block of Silicon need to be removed by various mechanisms to be later evacuated by slurry fragments. In the interest of decreasing operational costs during polycrystalline ingot slicing at Semiconductors Research Center, and, avoid environmental problems; it is necessary to recover the solar grade Silicon from the Silicon sawing waste. For this reason, the removal of metal fragments has become a preliminary requirement to regenerate the slurry; in addition, the solid phase needs to be separated from the liquid phase after the dissolution PEG with the solvent. In the present study, magnetic separation and centrifugation methods were adopted for metals removal, followed by the analysis of some operating parameters such as: washing time, pH, and initial concentration of Silicon. Finally, analytical, morphological and basic methods were performed in order to evaluate the efficiency of the process undertaken. [ABSTRACT FROM AUTHOR]