scholarly journals Spatial distribution of Kelvin-Helmholtz instability at low-latitude boundary layer under different solar wind speed conditions

2012 ◽  
Vol 117 (A8) ◽  
pp. n/a-n/a ◽  
Author(s):  
W. Y. Li ◽  
X. C. Guo ◽  
C. Wang
Keyword(s):  
Boundary Layer ◽  
Solar Wind ◽  
Spatial Distribution ◽  
Wind Speed ◽  
Solar Wind Speed ◽  
Helmholtz Instability ◽  
Low Latitude ◽  
Low Latitude Boundary Layer

scholarly journals Region-1 field aligned currents in experiments on laser-produced plasma interacting with magnetic dipole

2010 ◽  
Vol 6 (S274) ◽  
pp. 40-43
Author(s):  
I. F. Shaikhislamov ◽  
Yu. P. Zakharov ◽  
V. G. Posukh ◽  
E. L. Boyarintsev ◽  
A. V. Melekhov ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Boundary Layer ◽  
Solar Wind ◽  
Experimental Evidence ◽  
Magnetic Dipole ◽  
Present Report ◽  
Low Latitude ◽  
The Earth ◽  
Field Aligned Current ◽  
Low Latitude Boundary Layer

AbstractIn previous experiments by the authors a generation of intense field aligned current (FAC) system on Terrella poles was observed. In the present report a question of these currents origin in a low latitude boundary layer of magnetosphere is investigated. Experimental evidence of such a link was obtained by measurements of magnetic field generated by tangential sheared drag. Results suggest that compressional and Alfven waves are responsible for FAC generation. The study is most relevant to FAC generation in the Earth and Hermean magnetospheres following pressure jumps in Solar Wind.

scholarly journals Observation of three distinct ion populations at the Kelvin-Helmholtz-unstable magnetopause

2008 ◽  
Vol 26 (6) ◽  
pp. 1559-1566 ◽  
Author(s):  
M. G. G. T. Taylor ◽  
B. Lavraud
Keyword(s):  
Boundary Layer ◽  
Solar Wind ◽  
Solar Wind Plasma ◽  
Double Star ◽  
Single Event ◽  
Helmholtz Instability ◽  
Temperature Anisotropy ◽  
Low Latitude ◽  
Solar Wind Origin ◽  
Unambiguous Conclusion

Abstract. We report Double Star spacecraft observations of the dusk-flank magnetopause and its boundary layer under predominantly northward interplanetary magnetic field (IMF). Under such conditions the flank low-latitude boundary layers (LLBL) of the magnetosphere are known to broaden. The primary candidate processes associated with the transport of solar wind plasma into the LLBL are: (1) local diffusive plasma transport associated with the Kelvin-Helmholtz instability (KHI), (2) local plasma penetration owing to magnetic reconnection in the vicinity of the KHI-driven vortices, and (3) via a pre-existing boundary layer formed through double high-latitude reconnection on the dayside. Previous studies have shown that a cold population of solar wind origin is typically mixed with a hot population of magnetospheric origin in the LLBL. The present observations show the coexistence of three distinct ion populations in the dusk LLBL, during an interval when the magnetopause is unstable to the KHI: (1) a typical hot magnetospheric population, (2) a cold population that shows parallel temperature anisotropy, and (3) a distinct third cold population that shows perpendicular temperature anisotropy. Although no unambiguous conclusion may be drawn from this single event, we discuss the possible mechanisms at work and the origin of each population by envisaging three likely sources: hot magnetospheric plasma sheet, cold magnetosheath of solar wind origin, and cold plasma of ionospheric origin.

scholarly journals Investigation of the outer and inner low-latitude boundary layers

2001 ◽  
Vol 19 (9) ◽  
pp. 1065-1088 ◽  
Author(s):  
T. M. Bauer ◽  
R. A. Treumann ◽  
W. Baumjohann
Keyword(s):  
Boundary Layer ◽  
Solar Wind ◽  
Tangential Stress ◽  
Solar Wind Plasma ◽  
Alfven Wave ◽  
Bulk Velocity ◽  
Closed Field ◽  
Low Latitude ◽  
Field Lines ◽  
Low Latitude Boundary Layer

Abstract. We analyze 22 AMPTE/IRM crossings of the day-side low-latitude boundary layer for which a dense outer part can be distinguished from a dilute inner part. Whereas the plasma in the outer boundary layer (OBL) is dominated by solar wind particles, the partial densities of solar wind and magnetospheric particles are comparable in the inner boundary layer (IBL). For 11 events we find a reasonable agreement between observed plasma flows and those predicted by the tangential stress balance of an open magnetopause. Thus, we conclude that, at least in these cases, the OBL is formed by a local magnetic reconnection. The disagreement with the tangential stress balance in the other 11 cases might be due to reconnection being time-dependent and patchy. The north-south component of the proton bulk velocity in the boundary layer is, on average, directed toward high latitudes for both low and high magnetic shear across the magnetopause. This argues clearly against the possibility that the dayside low-latitude boundary layer is populated with solar wind plasma primarily from the cusps. "Warm", counterstreaming electrons that originate primarily from the magnetosheath and have a field-aligned temperature that is higher than the electron temperature in the magnetosheath by a factor of 1–5, are a characteristic feature of the IBL. Profiles of the proton bulk velocity and the density of hot ring current electrons provide evidence that the IBL is on closed field lines. Part of the IBL may be on newly opened field lines. Using the average spectra of electric and magnetic fluctuations in the boundary layer, we estimate the diffusion caused by lower hybrid drift instability, gyroresonant pitch angle scattering, or kinetic Alfvén wave turbulence. We find that cross-field diffusion cannot transport solar wind plasma into the OBL or IBL at a rate that would account for the thickness ( ~ 1000 km) of these sublayers. On the duskside, the dawn-dusk component of the proton bulk velocity in the IBL and magnetosphere is, on average, directed from the nightside toward local noon. Formation of the IBL may also be due to mechanisms operating in the magnetotail.Key words. Magnetospheric physics (magnetopause, cusp and boundary layer; magnetospheath)

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