scholarly journals Anisotropy of the Taylor scale and the correlation scale in plasma sheet magnetic field fluctuations as a function of auroral electrojet activity

2010 ◽  
Vol 115 (A12) ◽  
pp. n/a-n/a ◽  
Author(s):  
James M. Weygand ◽  
W. H. Matthaeus ◽  
M. El-Alaoui ◽  
S. Dasso ◽  
M. G. Kivelson
Keyword(s):  
Magnetic Field ◽  
Plasma Sheet ◽  
Auroral Electrojet ◽  
Field Fluctuations ◽  
Correlation Scale

scholarly journals Anisotropy of the Taylor scale and the correlation scale in plasma sheet and solar wind magnetic field fluctuations

2009 ◽  
Vol 114 (A7) ◽  
pp. n/a-n/a ◽  
Author(s):  
James M. Weygand ◽  
W. H. Matthaeus ◽  
S. Dasso ◽  
M. G. Kivelson ◽  
L. M. Kistler ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Plasma Sheet ◽  
Solar Wind Magnetic Field ◽  
Field Fluctuations ◽  
Correlation Scale

The Earth's plasma sheet as a laboratory for flow turbulence in high-β MHD

1997 ◽  
Vol 57 (1) ◽  
pp. 1-34 ◽  
Author(s):  
JOSEPH E. BOROVSKY ◽  
RICHARD C. ELPHIC ◽  
HERBERT O. FUNSTEN ◽  
MICHELLE F. THOMSEN
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Plasma Sheet ◽  
Sheet Material ◽  
Single Point ◽  
Power Laws ◽  
Fluxgate Magnetometer ◽  
Flow Measurements ◽  
Field Fluctuations ◽  
Flow Velocities

The bulk flows and magnetic-field fluctuations of the plasma sheet are investigated using single-point measurements from the ISEE-2 Fast Plasma Experiment and fluxgate magnetometer. Ten several-hour-long intervals of continuous data (with 3 s and 12 s time resolution) are analysed. The plasma-sheet flow appears to be strongly ‘turbulent’ (i.e. the flow is dominated by fluctuations that are unpredictable, with rms velocities[Gt ]mean velocities and with field fluctuations≈mean fields). The flow velocities are typically sub-Alfvénic. The flow-velocity probability distribution P(v) is constructed, and is found to be well fitted by exponential functions. Autocorrelation functions [Ascr ](τ) are constructed, and the autocorrelation times τcorr for the flow velocities are found to be about 2 min. From the flow measurements, an estimate of the mixing length in the plasma sheet is produced, yielding Lmix≈2 Earth radii; correspondingly, the plasma-sheet material appears to be well mixed in density and temperature. An eddy viscosity for the plasma sheet is also estimated. Power spectra, which are constructed from the v(t) and B(t) time series, have portions that are power laws with spectral indices that are near the range of those expected for turbulence theories. The plasma sheet may provide a laboratory for the study of turbulence in parameter regimes different from that of solar-wind turbulence: the plasma sheet is a β[Gt ]1, hot-ion plasma, and the turbulence may be strongly driven rather than well developed. The turbulent nature of the flow and the disordered nature of the magnetic field have implications for the transport of plasma-sheet material, for the penetration of the solar-wind electric field into the plasma sheet, and for the calculation of particle orbits in the magnetotail.

scholarly journals Observations of plasma vortices in the vicinity of flow-braking: a case study

2009 ◽  
Vol 27 (8) ◽  
pp. 3009-3017 ◽  
Author(s):  
K. Keika ◽  
R. Nakamura ◽  
M. Volwerk ◽  
V. Angelopoulos ◽  
W. Baumjohann ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Plasma Sheet ◽  
Convective Flow ◽  
Flow Patterns ◽  
Plasma Flows ◽  
Convective Flows ◽  
Field Fluctuations ◽  
Plasma Vortices

Abstract. We examine fast plasma flows and magnetic field fluctuations observed by THEMIS at 03:00–03:30 UT on 12 December 2007. All THEMIS probes are situated in the near-Earth plasma sheet (XSM>−10 RE) with 1–2 RE spacecraft separations in azimuthal and radial directions. We focus on the observations of plasma convective flows made simultaneously by more than one THEMIS probe. At about 03:10 UT and 03:14 UT, the THEMIS P2 probe observed earthward flows of >100 km/s. The THEMIS P1 probe, located duskward and earthward of P2, observed tailward flows under a positive Bz. The inner most probe THEMIS P4, located at almost the same MLT as THEMIS P1 and P2, did not see any clear flow. We examine the convective flow patterns for the THEMIS observations. We conclude that plasma vortices are formed near the region where the earthward flows slow down and turn in azimuthal directions.

scholarly journals Multi-scale magnetic field intermittence in the plasma sheet

2003 ◽  
Vol 21 (9) ◽  
pp. 1955-1964 ◽  
Author(s):  
Z. Vörös ◽  
W. Baumjohann ◽  
R. Nakamura ◽  
A. Runov ◽  
T. L. Zhang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Plasma Sheet ◽  
Large Scale ◽  
Sliding Window ◽  
Space Plasma ◽  
Space Plasma Physics ◽  
Multi Scale ◽  
Bursty Bulk Flow ◽  
Field Fluctuations ◽  
Scale Motion

Abstract. This paper demonstrates that intermittent magnetic field fluctuations in the plasma sheet exhibit transitory, localized, and multi-scale features. We propose a multifractal-based algorithm, which quantifies intermittence on the basis of the statistical distribution of the "strength of burstiness", estimated within a sliding window. Interesting multi-scale phenomena observed by the Cluster spacecraft include large-scale motion of the current sheet and bursty bulk flow associated turbulence, interpreted as a cross-scale coupling (CSC) process.Key words. Magnetospheric physics (magnetotail; plasma sheet) – Space plasma physics (turbulence)

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