Search Publications
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…
Evidence of a Cascade and Dissipation of Solar-Wind Turbulence at the Electron Gyroscale
Sahraoui, F.; Khotyaintsev, Yu. V.; Goldstein, M. L. +1 more
We report the first direct determination of the dissipation range of magnetofluid turbulence in the solar wind at the electron scales. Combining high resolution magnetic and electric field data of the Cluster spacecraft, we computed the spectrum of turbulence and found two distinct breakpoints in the magnetic spectrum at 0.4 and 35 Hz, which corre…
Universality of Solar-Wind Turbulent Spectrum from MHD to Electron Scales
Saur, J.; Alexandrova, O.; Schwartz, S. J. +4 more
To investigate the universality of magnetic turbulence in space plasmas, we analyze seven time periods in the free solar wind under different plasma conditions. Three instruments on Cluster spacecraft operating in different frequency ranges give us the possibility to resolve spectra up to 300 Hz. We show that the spectra form a quasiuniversal spec…
Global Scale-Invariant Dissipation in Collisionless Plasma Turbulence
Sahraoui, F.; Dunlop, M. W.; Khotyaintsev, Yu. V. +2 more
A higher-order multiscale analysis of the dissipation range of collisionless plasma turbulence is presented using in situ high-frequency magnetic field measurements from the Cluster spacecraft in a stationary interval of fast ambient solar wind. The observations, spanning five decades in temporal scales, show a crossover from multifractal intermit…
Observations of Turbulence Generated by Magnetic Reconnection
Eastwood, J. P.; Bale, S. D.; Phan, T. D. +1 more
Spacecraft observations of turbulence within a magnetic reconnection (guide field ∼0) ion diffusion region are presented. In the inertial subrange, electric and magnetic fluctuations both followed a -5/3 power law; at higher frequencies, the spectral indices were -1 and -8/3, respectively. The dispersion relation was found to be consistent with fa…
Supermagnetosonic Jets behind a Collisionless Quasiparallel Shock
Vainio, R.; Vaivads, A.; Lucek, E. A. +7 more
The downstream region of a collisionless quasiparallel shock is structured containing bulk flows with high kinetic energy density from a previously unidentified source. We present Cluster multispacecraft measurements of this type of supermagnetosonic jet as well as of a weak secondary shock front within the sheath, that allow us to propose the fol…
Scaling Laws of Turbulence and Heating of Fast Solar Wind: The Role of Density Fluctuations
Bruno, R.; Carbone, V.; Sorriso-Valvo, L. +2 more
Incompressible and isotropic magnetohydrodynamic turbulence in plasmas can be described by an exact relation for the energy flux through the scales. This Yaglom-like scaling law has been recently observed in the solar wind above the solar poles observed by the Ulysses spacecraft, where the turbulence is in an Alfvénic state. An analogous phenomeno…