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Turbulent impulsive magnetic energy release from electron scale reconnection
Horton, W.; Kim, J. -H.; Militello, F. +1 more
Magnetic reconnection may occur as bursts of nonlinear plasma dynamics on the electron collisionless skin length scale de=c/ωpe, during which a large fraction of the magnetic energy is converted to plasma thermal energy and plasma flow energy. An example of such a bursty energy release event is given with a simple set of…
Two fluid effects on three-dimensional reconnection in the Swarthmore Spheromak Experiment with comparisons to space dataa)
Brown, M. R.; Cothran, C. D.; Fung, J.
Several new experimental results are reported from spheromak merging studies at the Swarthmore Spheromak Experiment [M. R. Brown, Phys. Plasmas 6, 1717 (1999)] with relevance to three-dimensional (3D) reconnection in laboratory and space plasmas. First, recent velocity measurements of impurity ions using ion Doppler spectroscopy are reported. Bidi…
Wake formation behind positively charged spacecraft in flowing tenuous plasmas
Eriksson, A. I.; Engwall, E.; Forest, J.
Spacecraft in tenuous plasmas become positively charged because of photoelectron emission. If the plasma is supersonically drifting with respect to the spacecraft, a wake forms behind it. When the kinetic energy of the positive ions in the plasma is not sufficient to overcome the electrostatic barrier of the spacecraft potential, they scatter on t…
Larmor radius size density holes discovered in the solar wind upstream of Earth's bow shock
Dandouras, I.; Lucek, E.; Rème, H. +9 more
The Cluster and Double Star satellites recently observed plasma density holes upstream of Earth's collisionless bow shock to apogee distances of ∼19 and 13 earth radii, respectively. A survey of 147 isolated density holes using 4s time resolution data shows they have a mean duration of ∼17.9±10.4s, but holes as short as 4s are observed. The averag…
Anomalous resistivity due to nonlinear lower-hybrid drift waves
Vaivads, A.; Büchner, J.; Silin, I.
The generation of anomalous collision rate and resistivity by lower-hybrid drift waves is investigated. A general expression involving particle density and current perturbations and electromagnetic field fluctuations is used to estimate the effective collision frequency. Results of Vlasov-code simulations and Cluster spacecraft measurements sugges…
Wavelength and decay length of density overshoot structure in supercritical, collisionless bow shocks
Bale, S. D.; Horbury, T. S.; Saxena, R.
Above some critical Mach number, quasiperpendicular collisionless shocks are known to exhibit ``overshoot'' and ``undershoot'' structure thought to be associated with the motion of ions trapped at the shock front. Using spacecraft potential data from the Cluster spacecraft, the overshoot/undershoot density structure at 56 crossings of the quasiper…
Interpretation of Cluster data on chorus emissions using the backward wave oscillator model
Trakhtengerts, V. Y.; Demekhov, A. G.; Titova, E. E. +4 more
The measurements of chorus emissions by four closely separated Cluster spacecraft provide important information concerning the chorus generation mechanism. They confirm such properties of the wave source as their strong localization near the equatorial cross section of a magnetic flux tube, an almost parallel average wave-vector direction with res…
Wavelet analysis of magnetic turbulence in the Earth's plasma sheet
Balogh, A.; Zhang, T. L.; Nakamura, R. +4 more
Recent studies provide evidence for the multiscale nature of magnetic turbulence in the plasma sheet. Wavelet methods represent modern time series analysis techniques suitable for the description of statistical characteristics of multiscale turbulence. Cluster FGM (fluxgate magnetometer) magnetic field high-resolution (67 Hz) measurements are stud…
Dependence of frequency of nonlinear cold plasma cylindrical oscillations on electron density
Fainberg, J.; Osherovich, Vladimir
For cold plasma, the frequency of small amplitude Langmuir oscillations along one Cartesian coordinate is ωpo=√4πe2no/me , where np=no is the constant proton density which is equal to the average electron density ne¯. This formula for ωpo is the basis for measu…
Hamiltonian canonical formulation of Hall-magnetohydrodynamics: Toward an application to weak turbulence theory
Belmont, G.; Sahraoui, F.; Rezeau, L.
The different levels of description of fluid media [e.g., magnetohydrodynamics (MHD), Hall-magnetohydrodynamics, bi-fluid,…] are commonly known under the form of Newtonian systems of equations. Nevertheless, this form proves to be ill-suited to derive a fully analytical weak turbulence theory of these media, due to the well-known complexity of the…