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 (…
Dispersion relation analysis of solar wind turbulence
Glassmeier, K. -H.; Narita, Y.; Motschmann, U. +2 more
Frequency versus wave number diagram of turbulent magnetic fluctuations in the solar wind was determined for the first time in the wide range over three decades using four Cluster spacecraft. Almost all of the identified waves propagate quasi-perpendicular to the mean magnetic field at various phase speeds, accompanied by a transition from the dom…
Average magnetotail electron and proton pitch angle distributions from Cluster PEACE and CIS observations
Dandouras, I.; Fazakerley, A. N.; Owen, C. J. +2 more
We present results from the first systematic survey of proton and electron pitch angle distributions in the magnetotail, based on Cluster CIS and PEACE data binned by proton plasma β (βp). The proton distributions conform to the canonical picture of magnetotail ions - a boundary layer made up of Earthward streaming and bidirectional fie…
Excitation of banded whistler waves in the magnetosphere
Gary, S. Peter; Liu, Kaijun; Winske, Dan
Linear kinetic dispersion analysis and a two-dimensional electromagnetic particle-in-cell simulation are performed to demonstrate a possible excitation mechanism of banded whistler waves in the magnetosphere outside of the plasmapause. Whistler waves in the lower and the upper bands can be generated simultaneously by the whistler anisotropy instab…
Bipolar electric field signatures of reconnection separatrices for a hydrogen plasma at realistic guide fields
Divin, A.; Goldman, M. V.; Newman, D. L. +2 more
In preparation for the MMS mission we ask the question: how common are bipolar signatures linked to the presence of electron holes along separatrices emanating from reconnection regions? To answer this question, we conduct massively parallel simulations for realistic conditions and for the hydrogen mass ratio in boxes larger than considered in sim…
A statistical study of the propagation characteristics of whistler waves observed by Cluster
Khotyaintsev, Yuri V.; Agapitov, Oleksiy; Krasnoselskikh, Vladimir +1 more
VLF waves play a crucial role in the dynamics of radiation belts, and are responsible for the loss and the acceleration of energetic electrons. Modeling wave-particle interactions requires the best possible knowledge for how wave energy and wave-normal directions are distributed in L-shells and for the magnetic latitudes of different magnetic acti…
Whistler turbulence forward cascade: Three-dimensional particle-in-cell simulations
Chang, Ouliang; Wang, Joseph; Peter Gary, S.
The first fully three-dimensional particle-in-cell (PIC) simulation of whistler turbulence in a magnetized, homogeneous, collisionless plasma has been carried out. An initial relatively isotropic spectrum of long-wavelength whistlers is imposed upon the system, with an initial electron β = 0.10. As in previous two-dimensional simulations of whistl…
Large-amplitude whistler waves and electron acceleration
Yoon, Peter H.
A recent observation shows that large-amplitude whistler waves propagating obliquely with respect to the ambient magnetic field may be responsible for energizing the radiation belt electrons to relativistic energies (MeV) within a time scale as short as a fraction of a second. Test-particle simulations available in the literature invariably adopt …
Cluster observations of whistler mode ducts and banded chorus
Pickett, J. S.; Facskó, G.; Inan, U. S. +3 more
Bell et al. (2009) proposed that the source region for banded chorus consists of whistler mode ducts of depleted electron density (Ne) for upper band (UB) chorus for all wave normal angles ($\theta$) and ducts of either enhanced or depleted Ne for lower band (LB) chorus for small $\theta$ and $\theta$ near or greater than the…
Electromagnetic ion cyclotron waves in the helium branch induced by multiple electromagnetic ion cyclotron triggered emissions
Dandouras, Iannis; Omura, Yoshiharu; Shoji, Masafumi +3 more
Electromagnetic ion cyclotron (EMIC) triggered emissions with rising tones between the H+ and He+ cyclotron frequencies were found in the inner magnetosphere by the recent Cluster observations. Another type of EMIC wave with a constant frequency is occasionally observed below the He+ cyclotron frequency after the m…