scholarly journals A Case Study of Connection Between Ground Magnetic Field Perturbations and Tail Current Sheet Bursty Flows at X  = −60 R E

2018 ◽  
Vol 123 (3) ◽  
pp. 1822-1833 ◽  
Author(s):  
Chih-Ping Wang ◽  
Xiaoyan Xing ◽  
Yi-Hsin Liu ◽  
Andrei Runov
Keyword(s):  
Magnetic Field ◽  
Current Sheet ◽  
Tail Current ◽  
Ground Magnetic

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 Observations of the Earth's Cross-Tail Current Sheet and Their Implications

1985 ◽  
Vol 107 ◽  
pp. 303-307
Author(s):  
A. T. Y. Lui
Keyword(s):  
Magnetic Field ◽  
Current Sheet ◽  
Neutral Sheet ◽  
Magnetic Islands ◽  
Current Sheets ◽  
Tail Current ◽  
Sheet Surface ◽  
Magnetic Signatures ◽  
Wave Profiles

Observations of the neutral sheet in the Earth's magnetotail are presented to show different magnetic signatures of the neutral sheet which have been used to infer (1) wave profiles on the neutral sheet surface, (2) magnetic islands embedded in the neutral sheet, and (3) localized turbulent magnetic field regions. The occurrence of these features even at magnetospheric quiet conditions suggests that the above features are intrinsic to the current sheet and may possibly play a role in its stability. There are indications that these features are common to other current sheets in space.

scholarly journals Dayside isotropic precipitation of energetic protons

1997 ◽  
Vol 15 (10) ◽  
pp. 1233-1245 ◽  
Author(s):  
V. A. Sergeev ◽  
G. R. Bikkuzina ◽  
P. T. Newell
Keyword(s):  
Magnetic Field ◽  
Current Sheet ◽  
Equatorial Region ◽  
Closed Field ◽  
Activity Levels ◽  
Tail Current ◽  
Angle Scattering ◽  
Boundary Location ◽  
Proton Precipitation ◽  
Field Lines

Abstract. Recently it has been shown that isotropic precipitation of energetic protons on the nightside is caused by a non-adiabatic effect, namely pitch-angle scattering of protons in curved magnetic field lines of the tail current sheet. Here we address the origin of isotropic proton precipitation on the dayside. Computations of proton scattering regions in the magnetopheric models T87, T89 and T95 reveal two regions which contribute to the isotropic precipitation. The first is the region of weak magnetic field in the outer cusp which provides the 1–2° wide isotropic precipitation on closed field lines in a ~2–3 hour wide MLT sector centered on noon. A second zone is formed by the scattering on the closed field lines which cross the nightside equatorial region near the magnetopause which provides isotropic precipitation starting ≈ 1.5–2 h MLT from noon and which joins smoothly the precipitation coming from the tail current sheet. We also analyzed the isotropic proton precipitation using observations of NOAA low altitude polar spacecraft. We find that isotropic precipitation of >30 to >80 keV protons continues around noon forming the continuous oval-shaped region of isotropic precipitation. Part of this region lies on open field lines in the region of cusp-like or mantle precipitation, its equatorward part is observed on closed field lines. Near noon it extends ~1–2° below the sharp boundary of solar electron fluxes (proxy of the open/closed field line boundary) and equatorward of the cusp-like auroral precipitation. The observed energy dispersion of its equatorward boundary (isotropic boundary) agrees with model predictions of expected particle scattering in the regions of weak and highly curved magnetic field. We also found some disagreement with model computations. We did not observe the predicted split of the isotropic precipitation region into separate nightside and dayside isotropic zones. Also, the oval-like shape of the isotropic boundary has a symmetry line in 10–12 MLT sector, which with increasing activity rotates toward dawn while the latitude of isotropic boundary is decreasing. Our conclusion is that for both dayside and nightside the isotropic boundary location is basically controlled by the magnetospheric magnetic field, and therefore the isotropic boundaries can be used as a tool to probe the magnetospheric configuration in different external conditions and at different activity levels.

scholarly journals Asymmetry in the Earth’s magnetotail neutral sheet rotation due to IMF $$B_y$$ sign?

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Timo Pitkänen ◽  
Anita Kullen ◽  
Lei Cai ◽  
Jong-Sun Park ◽  
Heikki Vanhamäki ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Interplanetary Magnetic Field ◽  
Current Sheet ◽  
The Sun ◽  
Neutral Sheet ◽  
Tail Current ◽  
Cluster Data ◽  
The Asymmetry ◽  
The Cross ◽  
Possible Cause

AbstractEvidence suggests that a non-zero dawn–dusk interplanetary magnetic field (IMF $$B_y$$ B y ) can cause a rotation of the cross-tail current sheet/neutral sheet around its axis aligned with the Sun–Earth line in Earth’s magnetotail. We use Geotail, THEMIS and Cluster data to statistically investigate how the rotation of the neutral sheet depends on the sign and magnitude of IMF $$B_y$$ B y . In our dataset, we find that in the tail range of $$-30<$$ - 30 < XGSM $$<-15$$ < - 15 $$R_{\mathrm{E}}$$ R E , the degree of the neutral sheet rotation is clearly smaller, there appears no significant rotation or even, the rotation is clearly to an unexpected direction for negative IMF $$B_y$$ B y , compared to positive IMF $$B_y$$ B y . Comparison to a model by Tsyganenko et al. (2015, doi:10.5194/angeo-33-1-2015) suggests that this asymmetry in the neutral sheet rotation between positive and negative IMF $$B_y$$ B y conditions is too large to be explained only by the currently known factors. The possible cause of the asymmetry remains unclear.

Magnetic Current Imaging Techniques: Comparative Case Studies

2004 ◽  
Author(s):  
Olivier Crépel ◽  
Philippe Descamps ◽  
Patrick Poirier ◽  
Romain Desplats ◽  
Philippe Perdu ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Integrated Circuits ◽  
Case Studies ◽  
Flip Chip ◽  
Imaging Techniques ◽  
Optimal Domain ◽  
Magnetic Current ◽  
Comparative Case Studies ◽  
Current Flows

Abstract Magnetic field based techniques have shown great capabilities for investigation of current flows in integrated circuits (ICs). After reviewing the performances of SQUID, GMR (hard disk head technologies) and MTJ existing sensors, we will present results obtained on various case studies. This comparison will show the benefit of each approach according to each case study (packaged devices, flip-chip circuits, …). Finally we will discuss on the obtained results to classify current techniques, optimal domain of applications and advantages.

scholarly journals Solar wind and substorm excitation of the wavy current sheet

2009 ◽  
Vol 27 (6) ◽  
pp. 2457-2474 ◽  
Author(s):  
C. Forsyth ◽  
M. Lester ◽  
R. C. Fear ◽  
E. Lucek ◽  
I. Dandouras ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Current Sheet ◽  
Pressure Pulse ◽  
Wind Pressure ◽  
Expansion Velocity ◽  
Solar Wind Pressure ◽  
Wave Models ◽  
Best Fit ◽  
The Magnetic Field

Abstract. Following a solar wind pressure pulse on 3 August 2001, GOES 8, GOES 10, Cluster and Polar observed dipolarizations of the magnetic field, accompanied by an eastward expansion of the aurora observed by IMAGE, indicating the occurrence of two substorms. Prior to the first substorm, the motion of the plasma sheet with respect to Cluster was in the ZGSM direction. Observations following the substorms show the occurrence of current sheet waves moving predominantly in the −YGSM direction. Following the second substorm, the current sheet waves caused multiple current sheet crossings of the Cluster spacecraft, previously studied by Zhang et al. (2002). We further this study to show that the velocity of the current sheet waves was similar to the expansion velocity of the substorm aurora and the expansion of the dipolarization regions in the magnetotail. Furthermore, we compare these results with the current sheet wave models of Golovchanskaya and Maltsev (2005) and Erkaev et al. (2008). We find that the Erkaev et al. (2008) model gives the best fit to the observations.

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