Search Publications
Whistler Mode Waves and the Electron Heat Flux in the Solar Wind: Cluster Observations
Maksimovic, M.; Alexandrova, O.; de Conchy, Y. +5 more
The nature of the magnetic field fluctuations in the solar wind between the ion and electron scales is still under debate. Using the Cluster/STAFF instrument, we make a survey of the power spectral density and of the polarization of these fluctuations at frequencies f in [1, 400] Hz, during five years (2001-2005), when Cluster was in the free sola…
Kinetic Turbulence in the Terrestrial Magnetosheath: Cluster Observations
Sahraoui, F.; Deng, X. H.; Huang, S. Y. +5 more
We present a first statistical study of subproton- and electron-scale turbulence in the terrestrial magnetosheath using waveform data measured by the Cluster/STAFF search coil magnetometer in the frequency range [1, 180] Hz. It is found that clear spectral breaks exist near the electron scale, which separate two power-law-like frequency bands refe…
Nonlinear and Linear Timescales near Kinetic Scales in Solar Wind Turbulence
Matthaeus, W. H.; Chapman, S. C.; Karimabadi, H. +8 more
The application of linear kinetic treatments to plasma waves, damping, and instability requires favorable inequalities between the associated linear timescales and timescales for nonlinear (e.g., turbulence) evolution. In the solar wind these two types of timescales may be directly compared using standard Kolmogorov-style analysis and observationa…
Multi-spacecraft Observations of Linear Modes and Sideband Waves in Ion-scale Solar Wind Turbulence
Motschmann, Uwe; Glassmeier, Karl-Heinz; Narita, Yasuhito +1 more
In the scenario of weak turbulence, energy is believed to be cascaded from smaller to larger wave numbers and frequencies due to weak wave-wave interactions. Based on its perturbative treatment one may regard plasma turbulence as a superposition of linear modes (or normal modes) and sideband waves (or nonlinear modes). In this study, we use magnet…
Excitation of Kinetic Alfvén Waves by Fast Electron Beams
Chen, L.; Wu, D. J.; Zhao, G. Q. +2 more
Energetic electron beams, which are ubiquitous in a large variety of active phenomena in space and astrophysical plasmas, are one of the most important sources that drive plasma instabilities. In this paper, taking account of the return-current effect of fast electron beams, kinetic Alfvén wave (KAW) instability driven by a fast electron beam is i…
Oblique Alfvén Instabilities Driven by Compensated Currents
De Keyser, J.; Malovichko, P.; Voitenko, Y.
Compensated-current systems created by energetic ion beams are widespread in space and astrophysical plasmas. The well-known examples are foreshock regions in the solar wind and around supernova remnants. We found a new oblique Alfvénic instability driven by compensated currents flowing along the background magnetic field. Because of the vastly di…
Relaxation Processes in Solar Wind Turbulence
Carbone, V.; Gurgiolo, C.; Goldstein, M. L. +1 more
Based on global conservation principles, magnetohydrodynamic (MHD) relaxation theory predicts the existence of several equilibria, such as the Taylor state or global dynamic alignment. These states are generally viewed as very long-time and large-scale equilibria, which emerge only after the termination of the turbulent cascade. As suggested by hy…
Full Particle Electromagnetic Simulations of Entropy Generation across a Collisionless Shock
Wang, Rui; Yang, Zhongwei; Liu, Ying D. +5 more
Experimental data from Cluster have shown that entropy density can be generated across Earth's bow shock. These new observations are a starting point for a more sophisticated analysis that includes computer modeling of a collisionless shock using observed shock parameters as input. In this Letter, we present the first comparison between observatio…
Temperature Anisotropy in the Presence of Ultra Low Frequency Waves in the Terrestrial Foreshock
Eastwood, J. P.; Burgess, D.; Nakariakov, V. M. +3 more
We report the first study of the correlation between elevated solar wind core plasma temperatures and temperature anisotropy in the terrestrial foreshock. Plasma temperature is enhanced near the fire hose marginal stability threshold in the presence of ultra low frequency (ULF) large amplitude magnetic perturbations, which are intrinsically right-…