Search Publications
Fermi and betatron acceleration of suprathermal electrons behind dipolarization fronts
André, M.; Vaivads, A.; Fu, H. S. +1 more
Two dipolarization front (DF) structures observed by Cluster in the Earth midtail region (XGSM ≈ -15 RE), showing respectively the feature of Fermi and betatron acceleration of suprathermal electrons, are studied in detail in this paper. Our results show that Fermi acceleration dominates inside a decaying flux pileup region (…
Gyrokinetic Simulations of Solar Wind Turbulence from Ion to Electron Scales
Quataert, E.; Howes, G. G.; Schekochihin, A. A. +4 more
A three-dimensional, nonlinear gyrokinetic simulation of plasma turbulence resolving scales from the ion to electron gyroradius with a realistic mass ratio is presented, where all damping is provided by resolved physical mechanisms. The resulting energy spectra are quantitatively consistent with a magnetic power spectrum scaling of k-2.8
Bursty bulk flows and dipolarization in MHD simulations of magnetotail reconnection
Nakamura, R.; Hesse, M.; Birn, J. +1 more
Using three-dimensional MHD simulations of magnetic reconnection in the magnetotail, we investigate the fate of earthward bursty bulk flows (BBFs). The flow bursts are identified as entropy-depleted magnetic flux tubes (“bubbles”) generated by the severance of a plasmoid via magnetic reconnection. The onset of fast reconnection coincides closely w…
Plasma Jet Braking: Energy Dissipation and Nonadiabatic Electrons
André, M.; Vaivads, A.; Owen, C. J. +2 more
We report in situ observations by the Cluster spacecraft of wave-particle interactions in a magnetic flux pileup region created by a magnetic reconnection outflow jet in Earth’s magnetotail. Two distinct regions of wave activity are identified: lower-hybrid drift waves at the front edge and whistler-mode waves inside the pileup region. The whistle…
Phase diagram for magnetic reconnection in heliophysical, astrophysical, and laboratory plasmas
Ji, Hantao; Daughton, William
Recent progress in understanding the physics of magnetic reconnection is conveniently summarized in terms of a phase diagram which organizes the essential dynamics for a wide variety of applications in heliophysics, laboratory, and astrophysics. The two key dimensionless parameters are the Lundquist number and the macrosopic system size in units o…
Observations and simulations of non-local acceleration of electrons in magnetotail magnetic reconnection events
Hwang, Kyoung-Joo; Kivelson, Margaret G.; Schriver, David +6 more
Magnetic reconnection in magnetized plasmas represents a change in magnetic field topology and is associated with a concomitant energization of charged particles that results from a conversion of magnetic energy into particle energy. In Earth's magnetosphere this process is associated with the entry of the solar wind into the magnetosphere and wit…
Anisotropy of Alfvénic turbulence in the solar wind and numerical simulations
Horbury, T. S.; Chen, C. H. K.; Mallet, A. +2 more
We investigate the anisotropy of Alfvénic turbulence in the inertial range of slow solar wind and in both driven and decaying reduced magnetohydrodynamic simulations. A direct comparison is made by measuring the anisotropic second-order structure functions in both data sets. In the solar wind, the perpendicular spectral index of the magnetic field…
Thin current sheets in collisionless plasma: Equilibrium structure, plasma instabilities, and particle acceleration
Malova, H. V.; Popov, V. Yu.; Petrukovich, A. A. +2 more
The review is devoted to plasma structures with an extremely small transverse size, namely, thin current sheets that have been discovered and investigated by spacecraft observations in the Earth's magnetotail in the last few decades. The formation of current sheets is attributed to complicated dynamic processes occurring in a collisionless space p…
A statistical and event study of magnetotail dipolarization fronts
Nakamura, R.; Baumjohann, W.; Volwerk, M. +2 more
A study of dipolarization fronts of the Earth's magnetotail has been performed using seven years (2001-2007) of Cluster data. Events both with and without high-speed earthward flows are included. A superposed epoch analysis of the data shows that the dipolarization is preceeded by a decrease of Bz before the increase. The duration of th…
Triggering process of whistler mode chorus emissions in the magnetosphere
Omura, Yoshiharu; Nunn, David
Chorus emissions are triggered from the linear cyclotron instability driven by the temperature anisotropy of energetic electrons (10-100 keV) in the magnetosphere. Chorus emissions grow as an absolute nonlinear instability near the magnetic equator because of the presence of an electromagnetic electron hole in velocity space. The transition proces…