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Three Dimensional Anisotropic k Spectra of Turbulence at Subproton Scales in the Solar Wind
Belmont, G.; Sahraoui, F.; Rezeau, L. +2 more
We show the first three dimensional (3D) dispersion relations and k spectra of magnetic turbulence in the solar wind at subproton scales. We used the Cluster data with short separations and applied the k-filtering technique to the frequency range where the transition to subproton scales occurs. We show that the cascade is carried by highly oblique…
Anisotropy of Solar Wind Turbulence between Ion and Electron Scales
Alexandrova, O.; Horbury, T. S.; Chen, C. H. K. +3 more
The anisotropy of turbulence in the fast solar wind, between the ion and electron gyroscales, is directly observed using a multispacecraft analysis technique. Second order structure functions are calculated at different angles to the local magnetic field, for magnetic fluctuations both perpendicular and parallel to the mean field. In both componen…
In Situ Observations of a Secondary Magnetic Island in an Ion Diffusion Region and Associated Energetic Electrons
Wang, Shui; Lu, Quanming; Wang, Rongsheng +1 more
Numerical simulations have predicted that an extended current sheet may be unstable to secondary magnetic islands in the vicinity of the X line, and these islands can dramatically influence the reconnection rate. In this Letter, we present the first evidence of such a secondary island near the center of an ion diffusion region, which is consistent…
Observations of Slow Electron Holes at a Magnetic Reconnection Site
André, M.; Vaivads, A.; Owen, C. J. +3 more
We report in situ observations of high-frequency electrostatic waves in the vicinity of a reconnection site in the Earth’s magnetotail. Two different types of waves are observed inside an ion-scale magnetic flux rope embedded in a reconnecting current sheet. Electron holes (weak double layers) produced by the Buneman instability are observed in th…
Asymmetry of the Ion Diffusion Region Hall Electric and Magnetic Fields during Guide Field Reconnection: Observations and Comparison with Simulations
Eastwood, J. P.; Phan, T. D.; Øieroset, M. +1 more
In situ measurements of magnetic reconnection in the Earth’s magnetotail are presented showing that even a moderate guide field (20% of the reconnecting field) considerably distorts ion diffusion region structure. The Hall magnetic and electric fields are asymmetric and shunted away from the current sheet; an appropriately scaled particle-in-cell …
Wave-Vector Dependence of Magnetic-Turbulence Spectra in the Solar Wind
Glassmeier, K. -H.; Sahraoui, F.; Goldstein, M. L. +1 more
Using four-point measurements of the Cluster spacecraft, the energy distribution was determined for magnetic field fluctuations in the solar wind directly in the three-dimensional wave-vector domain in the range |k|≤1.5×10-3rad/km. The energy distribution exhibits anisotropic features characterized by a prominently extended structure pe…
Sign-Singularity of the Reduced Magnetic Helicity in the Solar Wind Plasma
Perri, S.; André, M.; Khotyaintsev, Y. +4 more
We investigate the scaling laws of a signed measure derived from the reduced magnetic helicity which has been determined from Cluster data in the solar wind. This quantifies the handedness of the magnetic field; namely, it can be related to the polarization of the magnetic field fluctuations (right or left hand). The measure results to be sign-sin…