Search Publications
Dissipation scales in the Earth's plasma sheet estimated from Cluster measurements
Balogh, A.; Nakamura, R.; Baumjohann, W. +5 more
In order to estimate the dissipation time-scale in magnetic turbulence in the plasma sheet a novel method is introduced for classification of velocity dependent patterns of two-point probability density functions' shapes near their maxima. For the first time, we provide evidence for Reynolds number (velocity) dependent widening of the inertial ran…
Solitary waves observed in the auroral zone: the Cluster multi-spacecraft perspective
Gurnett, D. A.; Balogh, A.; Lakhina, G. S. +15 more
We report on recent measurements of solitary waves made by the Wideband Plasma Wave Receiver located on each of the four Cluster spacecraft at 4.5-6.5RE (well above the auroral acceleration region) as they cross field lines that map to the auroral zones. These solitary waves are observed in the Wideband data as isolated bipolar and trip…
The strange physics of low frequency mirror mode turbulence in the high temperature plasma of the magnetosheath
Nakamura, R.; Constantinescu, O. D.; Treumann, R. A. +3 more
Mirror mode turbulence is the lowest frequency perpendicular magnetic excitation in magnetized plasma proposed already about half a century ago by Rudakov and Sagdeev (1958) and Chandrasekhar et al. (1958) from fluid theory. Its experimental verification required a relatively long time. It was early recognized that mirror modes for being excited r…
Characteristics of quasi-static potential structures observed in the auroral return current region by Cluster
André, M.; Buchert, S.; Kistler, L. M. +6 more
Temporal and spatial characteristics of intense quasi-static electric fields and associated electric potential structures in the return current region are discussed using Cluster observations at geocentric distances of about 5 Earth radii. Results are presented from four Cluster encounters with such acceleration structures to illustrate common as …
High frequency ion sound waves associated with Langmuir waves in type III radio burst source regions
MacDowall, R. J.; Thejappa, G.
Short wavelength ion sound waves (2-4kHz) are detected in association with the Langmuir waves (~15-30kHz) in the source regions of several local type III radio bursts. They are most probably not due to any resonant wave-wave interactions such as the electrostatic decay instability because their wavelengths are much shorter than those of Langmuir w…
Solitary potential structures observed in the magnetosheath by the Cluster spacecraft
Gurnett, D. A.; Balogh, A.; Pickett, J. S. +4 more
Bipolar pulses of ~ 25-100 µs in duration have been observed in the wave electric field data obtained by the Wideband plasma wave instrument on the Cluster spacecraft in the dayside magnetosheath. These pulses are similar in almost all respects to those observed on several spacecraft over the last few years. They represent solitary potential struc…
Large amplitude solitary waves in and near the EarthÂ’s magnetosphere, magnetopause and bow shock: Polar and Cluster observations
André, M.; Cattell, C.; Dombeck, J. +6 more
Solitary waves with large electric fields (up to 100's of mV/m) have been observed throughout the magnetosphere and in the bow shock. We discuss observations by Polar at high altitudes ( ~ 4-8 RE ), during crossings of the plasma sheet boundary and cusp, and new measurements by Polar at the equatorial magnetopause and by Cluster near the bow shock…
Model for vortex turbulence with discontinuities in the solar wind
Tsurutani, B. T.; Verkhoglyadova, O. P.; Dasgupta, B.
A model of vortex with embedded discontinuities in plasma flow is developed in the framework of ideal MHD in a low b plasma. Vortex structures are considered as a result of 2-D evolution of nonlinear shear Alfvén waves in the heliosphere. Physical properties of the solutions and vector fields are analyzed and the observational aspects of the model…
On ion-cyclotron-resonance heating of the corona and solar wind
Tu, C. -Y.; Marsch, E.; Vocks, C.
This paper concisely summarizes and critically reviews recent work by the authors on models of the heating of the solar corona by resonance of ions with high-frequency waves (up to the proton cyclotron frequency). The quasi-linear theory of pitch angle diffusion is presented in connection with relevant solar wind proton observations. Hybrid fluid-…
A study of magnetic fluctuations and their anomalous scaling in the solar wind: the Ulysses fast-latitude scan
Balogh, A.; Pagel, C.
The solar wind is a highly turbulent and intermittent medium at frequencies between 10-4 and 10-1 Hz. Power spectra are used to look at fluctuations in the components of the magnetic field at high frequencies over a wide range of latitudes. Results show steady turbulence in the polar regions of the Sun and a more varied envir…