Search Publications
Jet Deflection by Very Weak Guide Fields during Magnetic Reconnection
Goldman, M. V.; Newman, D. L.; Lapenta, G. +2 more
Previous 2D simulations of reconnection using a standard model of initially antiparallel magnetic fields have detected electron jets outflowing from the x point into the ion outflow exhausts. Associated with these jets are extended “outer electron diffusion regions.” New PIC simulations with an ion to electron mass ratio as large as 1836 (an H
Extended Magnetic Reconnection across the Dayside Magnetopause
Berchem, J.; Lavraud, B.; Wild, J. A. +18 more
The extent of where magnetic reconnection (MR), the dominant process responsible for energy and plasma transport into the magnetosphere, operates across Earth’s dayside magnetopause has previously been only indirectly shown by observations. We report the first direct evidence of X-line structure resulting from the operation of MR at each of two wi…
New Ion-Wave Path in the Energy Cascade
Perrone, Denise; Califano, Francesco; Valentini, Francesco +2 more
We present the results of kinetic numerical simulations that demonstrate the existence of a novel branch of electrostatic nonlinear waves driven by particle trapping processes. These waves have an acoustic-type dispersion with phase speed comparable to the ion thermal speed and would thus be heavily Landau damped in the linear regime. At variance …
Altitude Distribution of the Auroral Acceleration Potential Determined from Cluster Satellite Data at Different Heights
Karlsson, Tomas; Fazakerley, Andrew; Nilsson, Hans +6 more
Aurora, commonly seen in the polar sky, is a ubiquitous phenomenon occurring on Earth and other solar system planets. The colorful emissions are caused by electron beams hitting the upper atmosphere, after being accelerated by quasistatic electric fields at 1-2 RE altitudes, or by wave electric fields. Although aurora was studied by man…
Nonaxisymmetric Anisotropy of Solar Wind Turbulence
Chapman, S. C.; Hnat, B.; Turner, A. J. +2 more
A key prediction of turbulence theories is frame-invariance, and in magnetohydrodynamic (MHD) turbulence, axisymmetry of fluctuations with respect to the background magnetic field. Paradoxically the power in fluctuations in the turbulent solar wind are observed to be ordered with respect to the bulk macroscopic flow as well as the background magne…
Mirror Mode Expansion in Planetary Magnetosheaths: Bohm-like Diffusion
Tsurutani, Bruce T.; Hasegawa, Akira
Observed scale sizes of mirror modes in planetary magnetosheaths tend to be equal or larger than those that correspond to the maximum growth rate of the mirror instability: 9 ρp (proton gyroradius). These phenomena can be accounted for by introducing a diffusion process (Bohm) that shifts the spectra to lower wave numbers as the mode co…
Publisher's Note: Super-Alfvénic Propagation of Substorm Reconnection Signatures and Poynting Flux [Phys. Rev. Lett. 107, 065001 (2011)]
Eastwood, J. P.; Phan, T. D.; Drake, J. F. +1 more
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…