Slow‐mode shocks in the magnetotail

Saito, Yoshifumi; Mukai, T.; Terasawa, T.; Nishida, A.; Machida, S.; Hirahara, Masafumi; Maezawa, K.; Kokubun, S.; Yamamoto, T.

doi:10.1029/95ja01675

Cited by 103 publications

(95 citation statements)

References 30 publications

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“…The cold ions are heated and accelerated perpendicularly through slow-mode shocks (Omidi, 1995;Saito et al, 1995). The electron distribution functions in the downstream plasma sheet have a flat-top distribution along the magnetic field line (Feldman et al, 1985;Schwartz et al, 1987;Saito et al, 1995). The existence of backstreaming field-aligned ions in the upstream region from the slow-mode shock is well known.…”

Section: Discussionmentioning

confidence: 99%

“…From examination of a time sequence of the counterstreaming beams, we conclude that at least one of the two beams originated from cold ions in the lobe. The cold ions are heated and accelerated perpendicularly through slow-mode shocks (Omidi, 1995;Saito et al, 1995). The electron distribution functions in the downstream plasma sheet have a flat-top distribution along the magnetic field line (Feldman et al, 1985;Schwartz et al, 1987;Saito et al, 1995).…”

Section: Discussionmentioning

confidence: 99%

“…Hirahara et al (1994) have reported details of how the cold ions are accelerated in the plasma sheet boundary layer, and its association with enhancement of the convection electric field. Saito et al (1995) have also reported the heating of cold ions in the plasma sheet-lobe boundary which can be identified as a slow-mode shock.…”

Section: Instrumentationmentioning

confidence: 99%

See 2 more Smart Citations

Structure and Kinetic Properties of Plasmoids and Their Boundary Regions

Mukai

Fujimoto

Hoshino

et al. 1996

J. geomagn. geoelec

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Based on GEOTAIL/LEP observations in the distant magnetotail, this paper reports on several new features of velocity distribution functions of electrons and ions within a plasmoid and at its boundary. Here we use the term'plasmoid' in a wider meaning than usual in spite of the presence of significant magnetic By fields. In the lobe, as expected from MHD simulations of magnetic reconnection processes, cold plasmas are pushed away from the plasma sheet before the arrival of plasmoids, while after the plasmoid passage the convection is enhanced toward the normal direction to the plasma sheet. The cold ions flow into the plasmoid along magnetic field lines, are heated and accelerated perpendicularly at the boundary, and finally merge with hot plasmas deeper inside the plasmoids. Deep inside plasmoids, however, the ion distribution functions often show the existence of counterstreaming ion beams, while the simultaneously measured electron distribution functions show a flat-top distribution. It is noted that the presence of the counterstreaming ions is a fine structure along magnetic field lines inside the whole distribution convecting tailward with speeds of 500-900 km/s. The relative velocity of the two components along the magnetic field line reaches 1000-1500 km/s, which is much higher than the local Alfven speed. Each component has an anisotropic distribution with respect to its center in the velocity space; the perpendicular temperature is several times higher than the parallel temperature. We conclude that these counterstreaming ions are most likely of lobe origin, and they have not had time enough for thermalization. They might have entered the plasmoid from the northern and southern lobes, being heated and accelerated through slow-mode shocks at the boundaries. Hence, these field lines are open, and both ends are connected to the northern and southern lobes. This phenomenon is observed predominantly in the latter part of the plasmoid after southward turning of the magnetic field, especially after the plasma bulk speed has increased stepwise and the Ba/B, field magnitudes have attained the peak value. It is also observed even near the neutral sheet, where the magnetic Bs field is very small, but significant By and/or B. fields exist. Since the tailward flow speed becomes faster associated with the above phenomenon, these open field lines would be draped around the leading (core) part of plasmoids. The compression due to the draping may increase the field intensity.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Structure and Kinetic Properties of Plasmoids and Their Boundary Regions

Mukai

Fujimoto

Hoshino

et al. 1996

J. geomagn. geoelec

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“…The slow shocks were observed in the distant tail (X<−100 R E ) on the lobe-plasma sheet boundary (e.g. Saito et al, 1995) and on the plasmoid boundaries at X∼−100 R E (Mukai et al, 1996). Recently, Eriksson et al (2004) reported observations of reconnection related shocks in the near-Earth tail.…”

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confidence: 97%

Structure of the near-Earth plasma sheet during tailward flows

et al. 2008

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Abstract.A detailed analysis of successive tailward flow bursts in the near-Earth magnetotail (X∼−19 R E ) plasma sheet is performed on the basis of in-situ multi-point observations by the Cluster spacecraft on 15 September 2001. The tailward flows were detected during a northward IMF interval, 2.5 h after a substorm expansion. Each flow burst (V x <300 km/s) was associated with local auroral activation. Enhancements of the parallel and anti-parallel ∼1 keV electron flux were detected during the flows. The spacecraft configuration enables to monitor the neutral sheet (B x ≈0) and the level of B x ≈10-15 nT simultaneously, giving a possibility to distinguish between closed plasmoid-like structures and open NFTE-like surges. The data analysis shows NFTElike structures and localized current filaments embedded into the tailward plasma flow. 3-D shapes of the structures were reconstructed using the four-point magnetic filed measurements and the particle data.

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“…A small number of slow shocks have been observed in interplanetary space (Chao and Olbert, 1970;Burlaga and Chao, 1971;Richter et al, 1985;Whang et al, 1996) and in the magnetotail (Feldman et al, , 1985(Feldman et al, , 1987Smith et al, 1984;Seon et al, 1995;Saito et al, 1995Saito et al, , 1996.…”

Section: Introductionmentioning

confidence: 99%

Theory and observation of double discontinuities

Whang

2004

Nonlin. Processes Geophys.

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Abstract. Recent research using high-resolution magnetic field data to examine the interior structures of MHD shocks in interplanetary space and in the magnetotail led to a surprising discovery that a slow-mode shock is often followed by an adjoining rotational discontinuity layer on the postshock side. The thickness of each layer is of the order of a few ion inertial lengths. Such a compound structure is known as a double discontinuity. When the magnetic field rotates by several degrees per ion inertial length inside a thin layer, the Hall current term becomes important in the generalized Ohm's law. Steady state solutions based on the Hall-MHD theory have been obtained to show the merging of a rotational layer and a slow shock layer to form a compound structure like the observed double discontinuities.

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Slow‐mode shocks in the magnetotail

Cited by 103 publications

References 30 publications

Structure and Kinetic Properties of Plasmoids and Their Boundary Regions

Structure and Kinetic Properties of Plasmoids and Their Boundary Regions

Structure of the near-Earth plasma sheet during tailward flows

Theory and observation of double discontinuities

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