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Thin Current Sheets and Associated Electron Heating in Turbulent Space Plasma
Vaivads, A.; Sahraoui, F.; Khotyaintsev, Yu. V. +6 more
Intermittent structures, such as thin current sheets, are abundant in turbulent plasmas. Numerical simulations indicate that such current sheets are important sites of energy dissipation and particle heating occurring at kinetic scales. However, direct evidence of dissipation and associated heating within current sheets is scarce. Here, we show a …
A Statistical Study of the Solar Wind Turbulence at Ion Kinetic Scales Using the k-filtering Technique and Cluster Data
Li, X.; Roberts, O. W.; Jeska, L.
Plasma turbulence at ion kinetic scales in the solar wind is investigated using the multi-point magnetometer data from the Cluster spacecraft. By applying the k-filtering method, we are able to estimate the full three-dimensional power spectral density P(ωsc, k) at a certain spacecraft frequency ωsc in wavevector (k) space. B…
Energy Dissipation in Magnetic Null Points at Kinetic Scales
Lapenta, Giovanni; Eriksson, Elin; Divin, Andrey +2 more
We use kinetic particle-in-cell and MHD simulations supported by an observational data set to investigate magnetic reconnection in clusters of null points in space plasma. The magnetic configuration under investigation is driven by fast adiabatic flux rope compression that dissipates almost half of the initial magnetic field energy. In this phase …
Multi-spacecraft Measurement of Turbulence within a Magnetic Reconnection Jet
Khotyaintsev, Yu. V.; Matthaeus, W. H.; Chapman, S. C. +3 more
The relationship between magnetic reconnection and plasma turbulence is investigated using multipoint in situ measurements from the Cluster spacecraft within a high-speed reconnection jet in the terrestrial magnetotail. We show explicitly that work done by electromagnetic fields on the particles, {\boldsymbol{J}}\cdot {\boldsymbol{E}}, has a non-G…
Evidence of the Ion Cyclotron Resonance at Proton Kinetic Scales in the Solar Wind
Li, Xing; Roberts, O. W.
The k-filtering and wave polarization techniques are applied to Cluster magnetic field data at four intervals of fast free (not connected to Earth's foreshock) solar wind. In addition to the commonly observed population of magnetic field fluctuations propagating at quasi-perpendicular angles to the global mean field B0 , a population of…
On Multiple Reconnection X-lines and Tripolar Perturbations of Strong Guide Magnetic Fields
Lavraud, B.; Khotyaintsev, Yu. V.; Carr, C. M. +7 more
We report new multi-spacecraft Cluster observations of tripolar guide magnetic field perturbations at a solar wind reconnection exhaust in the presence of a guide field BM which is almost four times as strong as the reversing field BL. The novel tripolar field consists of two narrow regions of depressed BM, with an…
The Three-dimensional Evolution of Ion-scale Current Sheets: Tearing and Drift-kink Instabilities in the Presence of Proton Temperature Anisotropy
Matteini, L.; Burgess, D.; Gingell, P. W.
We present the first three-dimensional (3D) hybrid simulations of the evolution of ion-scale current sheets, with an investigation of the role of temperature anisotropy and associated kinetic instabilities on the growth of the tearing instability and particle heating. We confirm the ability of the ion cyclotron and firehose instabilities to enhanc…
The Role of Large Amplitude Upstream Low-frequency Waves in the Generation of Superthermal Ions at a Quasi-parallel Collisionless Shock: Cluster Observations
Wang, Shui; Huang, Can; Guo, Fan +3 more
The superthermal ions at a quasi-parallel collisionless shock are considered to be generated during the reformation of the shock. Recently, hybrid simulations of a quasi-parallel shock have shown that during the reformation of a quasi-parallel shock the large-amplitude upstream low-frequency waves can trap the reflected ions at the shock front whe…
Statistics of the Velocity Gradient Tensor in Space Plasma Turbulent Flows
Consolini, Giuseppe; Materassi, Massimo; Federica Marcucci, Maria +1 more
In the last decade, significant advances have been presented for the theoretical characterization and experimental techniques used to measure and model all of the components of the velocity gradient tensor in the framework of fluid turbulence. Here, we attempt the evaluation of the small-scale velocity gradient tensor for a case study of space pla…
Statistical and Scaling Features of Fluctuations in the Dissipation Range During a Reconnection Event
Consolini, G.; Marcucci, M. F.; Pallocchia, G. +2 more
Reconnection events in space plasmas are accompanied by the occurrence of large-amplitude turbulent fluctuations of the magnetic and electric field, covering a wide range of temporal and spatial scales. Here, we study the scaling and statistical features of magnetic and electric field fluctuations below the ion-gyroperiod (i.e., in the dissipation…