Search Publications
Kinetic Alfvén Wave Turbulence and Transport through a Reconnection Diffusion Region
Acuna, M.; Reme, H.; Goldstein, M. L. +3 more
We demonstrate from observations that kinetic Alfvén waves may play an important role in facilitating magnetic reconnection. These waves radiate outwards from the diffusion region oblique to the magnetic field in a conelike pattern delimited by the X line separatrices with outward energy fluxes equivalent to that contained in the outstreaming ions…
Reconnection at High Latitudes: Antiparallel Merging
Escoubet, C. P.; Dunlop, M. W.; Fear, R. C. +5 more
New investigations have renewed the debate on the occurrence of magnetic reconnection of Earth’s dayside magnetopause. Here, we show for the first time strong evidence for a high-latitude reconnection site, located on initially closed field lines, where the magnetic field orientations inside and outside the magnetopause are close to antiparallel. …
Is There a Dark Matter Signal in the Galactic Positron Annihilation Radiation?
Rothschild, R. E.; Higdon, J. C.; Lingenfelter, R. E.
Assuming Galactic positrons do not go far before annihilating, a difference between the observed 511 keV annihilation flux distribution and that of positron production, expected from β+ decay in Galactic iron nucleosynthesis, was evoked as evidence of a new source and signal of dark matter. We show, however, that the dark matter sources…
Nonlinear Development of Shocklike Structure in the Solar Wind
Parks, G. K.; Lin, N.; Lee, E. +1 more
We report first in situ multispacecraft observations of nonlinear steepening of compressional pulses in the solar wind upstream of Earth’s bow shock. The magnetic field of a compressional pulse formed at the upstream edge of density holes is shown to suddenly break and steepen into a shocklike structure. During the early phase of development therm…
Counterstreaming Beams and Flat-Top Electron Distributions Observed with Langmuir, Whistler, and Compressional Alfvén Waves in Earth's Magnetic Tail
Parks, George K.; Teste, Alexandra
Relevant new clues to wave-particle interactions have been obtained in Earth’s plasma sheet (PS). The plasma measurements made on Cluster spacecraft show that broadband (∼2-6kHz) electrostatic emissions, in the PS boundary layer, are associated with cold counterstreaming electrons flowing at 5-12×103kms-1 through hot Maxwelli…
Generalized Similarity in Finite Range Solar Wind Magnetohydrodynamic Turbulence
Chapman, S. C.; Nicol, R. M.
Extended or generalized similarity is a ubiquitous but not well understood feature of turbulence that is realized over a finite range of scales. The ULYSSES spacecraft solar polar passes at solar minimum provide in situ observations of evolving anisotropic magnetohydrodynamic turbulence in the solar wind under ideal conditions of fast quiet flow. …
Anomalous Orbital-Energy Changes Observed during Spacecraft Flybys of Earth
Anderson, John D.; Campbell, James K.; Ekelund, John E. +2 more
We report and characterize anomalous orbital-energy changes observed during six Earth flybys by the Galileo, NEAR, Cassini, Rosetta, and MESSENGER spacecraft. These anomalous energy changes are consistent with an empirical prediction formula which is proportional to the total orbital energy per unit mass and which involves the incoming and outgoin…
Magnetosheath Plasma Turbulence and Its Spatiotemporal Evolution as Observed by the Cluster Spacecraft
André, M.; Vaivads, A.; Vörös, Z. +2 more
We study the plasma turbulence, at scales larger than the ion inertial length scale, downstream of a quasiparallel bow shock using Cluster multispacecraft measurements. We show that turbulence is intermittent and well described by the extended structure function model, which takes into account the spatial inhomogeneity of the cascade rate. For the…
Characteristic Parameters of Drift Vortices Coupled to Alfvén Waves in an Inhomogeneous Space Plasma
Sundkvist, David; Bale, Stuart D.
We present detailed measurements of ion scale vortices of drift type coupled to Alfvén waves in an inhomogeneous and collisionless space magnetoplasma. The two free parameters of a dipolar vortex, intensity and spatial radius, are measured. The vortices are driven by a strong density gradient on a boundary layer with scale size of the same order a…
Observation of Inertial Energy Cascade in Interplanetary Space Plasma
Bavassano, B.; Pietropaolo, E.; Bruno, R. +6 more
Direct evidence for the presence of an inertial energy cascade, the most characteristic signature of hydromagnetic turbulence (MHD), is observed in the solar wind by the Ulysses spacecraft. After a brief rederivation of the equivalent of Yaglom’s law for MHD turbulence, a linear relation is indeed observed for the scaling of mixed third-order stru…