A new particle population near the high-latitude plasma sheet

2001 ◽  
Vol 106 (A12) ◽  
pp. 29669-29682 ◽  
Author(s):  
M. Wilber ◽  
Q. Li ◽  
R. M. Winglee ◽  
G. K. Parks ◽  
M. McCarthy ◽  
...  
Keyword(s):  
High Latitude ◽  
Plasma Sheet ◽  
Particle Population

scholarly journals <i>Letter to the Editor</i> Why do ultra-low-frequency MHD oscillations with a discrete spectrum exist in the magnetosphere?

2005 ◽  
Vol 23 (3) ◽  
pp. 1075-1079 ◽  
Author(s):  
A. S. Leonovich ◽  
V. A. Mazur
Keyword(s):  
Discrete Spectrum ◽  
Observational Data ◽  
High Latitude ◽  
Plasma Sheet ◽  
Low Frequency ◽  
Magnetosonic Wave ◽  
Letter To The Editor ◽  
Morning Sector ◽  
Good Agreement

Abstract. A new concept of the global magnetospheric resonator is suggested for fast magnetosonic waves in which the role of the resonator is played by the near-Earth part of the plasma sheet. It is shown that the magnetosonic wave is confined in this region of the magnetosphere within its boundaries. The representative value of the resonator's eigenfrequency estimated at f~1MHz is in good agreement with observational data of ultra-low-frequency MHD oscillations of the magnetosphere with a discrete spectrum (f~0.8, 1.3, 1.9, 2.6...MHz). The theory explains the ground-based localization of the oscillations observed in the midnight-morning sector of the high-latitude magnetosphere.

scholarly journals Solar wind control of plasma number density in the near-Earth plasma sheet: three-dimensional structure

2008 ◽  
Vol 26 (12) ◽  
pp. 4031-4049 ◽  
Author(s):  
D. Nagata ◽  
S. Machida ◽  
S. Ohtani ◽  
Y. Saito ◽  
T. Mukai
Keyword(s):  
Solar Wind ◽  
Density Dependence ◽  
High Latitude ◽  
Plasma Sheet ◽  
Strong Dependence ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Lower Latitude ◽  
Number Density ◽  
Three Dimensional Structure

Abstract. The plasma number density in the near-Earth plasma sheet depends on the solar wind number density and the north-south component of interplanetary magnetic field (IMF Bz) with time lag and duration of several hours. We examined the three-dimensional structure of such dependences by fitting observations of plasma sheet and solar wind to an empirical model equation. Analyses were conducted separately for northward and southward IMF conditions. Effects of solar wind speed and IMF orientation were also examined by further subdivision of the dataset. Based on obtained results, we discuss (i) the relative contribution of the ionosphere and solar wind to plasma sheet mass supply, (ii) the entry mechanisms for magnetosheath particles, and (iii) the plasma transport in the plasma sheet. We found that solar wind number density dependence is weaker and IMF Bz dependence is stronger for faster solar wind with southward IMF, which suggests the contribution of ionospheric particles. Further from the Earth, different interplanetary conditions result in different structures of solar wind dependence, which indicate different solar wind entry mechanisms: (1) southward IMF results in a strong dependence on solar wind number density in the flank high-latitude region, (2) slow solar wind with northward IMF leads to lower-latitude peaks of solar wind number density dependence in the flank region, (3) fast solar wind with northward IMF results in a strong dependence on solar wind number density at the down-tail dusk flank equator, and (4) solar wind number density dependence is stronger in the downstream of quasi-parallel bow shock. These features are attributable to (1) low-latitude dayside reconnection entry, (2) high-latitude dayside reconnection entry, (3) entry due to decay of Kelvin-Helmholtz vortices, and (4) diffusive entry mediated by kinetic Alfven waves, respectively. Effect of IMF Bz and its time lags show plasma sheet reconfiguration associated with enhanced convective transport under southward IMF. Duration of IMF Bz effect under northward IMF is interpreted in terms of turbulent diffusive transport.

scholarly journals Recirculation of plasma sheet particles into the high-latitude boundary layer

1998 ◽  
Vol 103 (A11) ◽  
pp. 26521-26532 ◽  
Author(s):  
D. C. Delcourt ◽  
J.-A. Sauvaud
Keyword(s):  
Boundary Layer ◽  
High Latitude ◽  
Plasma Sheet

scholarly journals The current sheet flapping motions induced by non-adiabatic ions: case study

2018 ◽  
Author(s):  
Xinhua Wei ◽  
Chunlin Cai ◽  
Henri Rème ◽  
Iannis Dandouras ◽  
George Parks
Keyword(s):  
Magnetic Field ◽  
Current Sheet ◽  
Field Line ◽  
Magnetic Field Line ◽  
Plasma Sheet ◽  
Plasma Sources ◽  
Shear Structures ◽  
Particle Population ◽  
Alternating Bending

Abstract. In this paper, we analyzed the y-component of magnetic field line curvature in the plasma sheet and found that there are two kinds of shear structures of the flapping current sheet, i.e. symmetric and antisymmetric. The alternating bending orientations of guiding field are exactly corresponding to alternating north-south asymmetries of the bouncing ion population in the sheet center. Those alternating asymmetric plasma sources consequently induce the current sheet flapping motion as a driver. In addition, a substantial particle population with dawnward motion was observed in the center of a bifurcated current sheet. This population is identified as the quasi-adiabatic particles, and provides a net current opposite to the conventional cross-tail current.

scholarly journals Cluster EDI convection measurements across the high-latitude plasma sheet boundary at midnight

2001 ◽  
Vol 19 (10/12) ◽  
pp. 1669-1681 ◽  
Author(s):  
J. M. Quinn ◽  
G. Paschmann ◽  
R. B. Torbert ◽  
H. Vaith ◽  
C. E. McIlwain ◽  
...  
Keyword(s):  
Electric Fields ◽  
High Latitude ◽  
Plasma Sheet ◽  
Boundary Region ◽  
Electron Drift ◽  
Polar Cap ◽  
Static Structure ◽  
Boundary Crossings ◽  
Instruments And Techniques ◽  
Using Data

Abstract. We examine two crossings of three Cluster satellites from the polar cap into the high-latitude plasma sheet at midnight local time, using data from the Electron Drift Instrument (EDI). EDI measures the full electron drift velocity in the plane perpendicular to the magnetic field for any field and drift directions. The context of the measured convection velocities is established by their relation to the intense enhancements in 1 keV electrons, also measured by EDI, as the satellites move from the polar cap into the plasma sheet boundary. In both cases presented here, the cross B convection in the polar cap is anti-sunward (toward the nightside plasma sheet) with a small duskward component. As the satellites enter the plasma sheet boundary region, the dawn-dusk convective flow component reverses its sign, and the flow in the meridianal plane (toward the center of the plasma sheet) drops substantially. The relatively stable convection in the polar cap becomes highly variable as the PSBL is encountered. The timing and sequence of the boundary crossings by the Cluster satellites are consistent with a relatively static structure on a time scale of the few minutes in satellite separations. In one of the two events, the plasma sheet boundary has a spatially separate structure that is crossed by the satellites before entering the plasma sheet.Key words. Magnetospheric physics (electric fields; magnetopause, cusp and boundary layers; instruments and techniques)

Particle and field characteristics of the high-latitude plasma sheet boundary layer

1984 ◽  
Vol 89 (A10) ◽  
pp. 8885 ◽  
Author(s):  
G. K. Parks ◽  
M. McCarthy ◽  
R. J. Fitzenreiter ◽  
J. Etcheto ◽  
K. A. Anderson ◽  
...  
Keyword(s):  
Boundary Layer ◽  
High Latitude ◽  
Plasma Sheet ◽  
Plasma Sheet Boundary Layer

scholarly journals Geotail observations of two-component protons in the midnight plasma sheet

2007 ◽  
Vol 25 (10) ◽  
pp. 2229-2245 ◽  
Author(s):  
M. N. Nishino ◽  
M. Fujimoto ◽  
G. Ueno ◽  
K. Maezawa ◽  
T. Mukai ◽  
...  
Keyword(s):  
High Latitude ◽  
Plasma Sheet ◽  
Transport Process ◽  
Cold Plasma ◽  
Plasma Transport ◽  
Helmholtz Instability ◽  
Low Latitude ◽  
Vortical Structures ◽  
Two Component ◽  
To Come

Abstract. Through the effort to obtain clues toward understanding of transport of cold plasma in the near-Earth magnetotail under northward IMF, we find that two-component protons are observed in the midnight plasma sheet (−10>XGSM>−30 RE, |YGSM| <10 RE) under northward IMF by the Geotail spacecraft. Since the two-component protons are frequently observed on the duskside during northward IMF intervals but hardly on the dawnside, those found in the midnight plasma sheet are thought to come from the dusk flank. The cold proton component in the midnight region occasionally has a parallel anisotropy, which resembles that in the tail flank on the duskside. The flows in the plasma sheet with two-component protons were quite stagnant or slightly going dawnward, which supports the idea that the observed two-component protons in the midnight region are of duskside origin. Because the two-component protons in the midnight plasma sheet emerge under strongly northward IMF with the latitudinal angle larger than 45 degrees, and because the lag from the strongly northward IMF to the emergence can be as short as a few hours, we suggest that prompt plasma transport from the dusk to midnight region occurs under strongly northward IMF. We propose that the dawnward flows result from viscous interaction between the high-latitude portion of the plasma sheet and the lobe cell. Another candidate for plasma transport process from the dusk to the midnight region is turbulent flow due to vortical structures of the Kelvin-Helmholtz instability that developed around the dusk low-latitude boundary under strongly northward IMF. In addition, we also suggest that gradual cooling of hot protons under northward IMF is a global phenomenon in the near-Earth magnetotail.

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