Disruption of parallel current at substorm breakup

Perraut, S.; Contel, O. Le; Roux, A.; Pellat, R.; Korth, A.; Holter, Ø.; Pedersen, Å.

doi:10.1029/2000gl000054

Cited by 19 publications

(17 citation statements)

References 16 publications

(2 reference statements)

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“…Further analysis of GEOS-2 data (at the geostationary orbit) suggested that substorm onset and impulsive plasma transport is controlled by a micro-instability with frequencies around the proton gyrofrequency such as a parallel current instability (Perraut et al 2000a(Perraut et al , 2000bLe Contel et al 2001a, 2001b. The regular occurrence at different radial distances (at the geostationary orbit with GEOS-2, at 10 R E with Geotail and 20 R E with Cluster) of wave activity around the proton gyrofrequency at substorm onset was also noted by Le Contel et al (2002).…”

Section: Introductionmentioning

confidence: 98%

First Results of the THEMIS Search Coil Magnetometers

Contel¹,

Roux²,

Robert³

et al. 2008

Space Sci Rev

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132

124

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We present the first data from the THEMIS Search Coil Magnetometers (SCM), taken between March and June 2007 while the THEMIS constellation apogee moved from the duskside toward the dawnside. Data reduction, especially the SCM calibration method and spurious noise reduction process, is described. The signatures of magnetic fluctuations in key magnetospheric regions such as the bow shock, the magnetopause and the magnetotail during a substorm, are described. We also discuss the role that magnetic fluctuations could play in plasma transport, acceleration and heating.

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Section: Introductionmentioning

confidence: 98%

First Results of the THEMIS Search Coil Magnetometers

Contel¹,

Roux²,

Robert³

et al. 2008

Space Sci Rev

Self Cite

132

124

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“…Wave activation is often observed at substorms. At the geostationary orbit, small‐scale Alfvénic fluctuations are systematically observed at substorm onset and during the expansion phase [ Perraut et al , 2000b]. As shown by Le Contel et al [2001b], plasma transport can be controlled by the amplitude of these waves.…”

Section: Introductionmentioning

confidence: 99%

Substorm expansion phase: Observations from Geotail, Polar and IMAGE network

et al. 2003

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We describe the signature of a substorm detected in the midtail while Geotail was located close to the midnight meridian. At the same time, the UVI imager on board Polar identifies a bulge which develops at low latitude and rapidly expands towards the north, east, and west, corresponding to the expansion phase. The magnetograms of the IMAGE network are consistent with these observations; during the expansion phase they give evidence for a northward expansion of the magnetic perturbation. Mapping indicates that the Geotail footprint is located north of the initial bulge and south of the high‐latitude oval. During the expansion phase, Geotail is located in the center of the neutral sheet and detects an ion flow velocity, perpendicular to Bo and directed tailward while Bz changes from positive to negative. During the recovery phase, Geotail, which is not at the center of the sheet anymore, detects an ion velocity directed earthward but essentially field aligned, while Bz is positive and the high‐latitude auroral structure is located north of Geotail footprint. The radial component of the velocity is always dominant. We interpret these observations as evidence for a tailward moving dipolarization front that first destroys the inner part of the thin current sheet (TCS) formed during the growth phase. This dipolarization/current disruption starts in the near‐Earth plasma sheet and expands tailward. This “erosion” produces a negative Bz component at the earthward edge of the TCS. For large enough distances this contribution can eventually be dominant, thereby producing a negative Bz. In this interpretation the formation of an X‐point/X‐line is the consequence of the erosion of the currents in near‐Earth tail. Present observations give evidence for an association between increases in the ion velocity and small‐scale Alfvenic fluctuations. The plasma sheet electrons are heated via interaction with the waves. This heating is preferentially along the direction of the magnetic field. Large ion flow velocities coincide with wave observations.

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“…Impulsive increases (as short lasting bursts) of these waves were regularly observed at the GEOS 2 during the substorm magnetic field dipolarization (Perraut et al, 1993(Perraut et al, , 2000Le Contel et al, 2001). These spatially localized waves are related to field-aligned currents, Perraut et al (2000) called them the current-driven Alfvén (CDA) waves.…”

Section: Oscillations Associated With a Sharp Front Of Energetic Ionsmentioning

confidence: 99%

“…These spatially localized waves are related to field-aligned currents, Perraut et al (2000) called them the current-driven Alfvén (CDA) waves. Bursts of CDA waves coincide with the increases in the flux of electrons with energy >20 keV at pitch-angles ∼90 • and, simultaneously, with the increases of low-energy (2.5-7 keV) electron fluxes at pitch-angles <20 • (Perraut et al, 1993(Perraut et al, , 2000. Also, the high-intensity CDA waves may isotropize and heat the ions (Perraut et al, 1998).…”

Section: Oscillations Associated With a Sharp Front Of Energetic Ionsmentioning

confidence: 99%

Alternating bursts of low energy ions and electrons near the substorm onset

et al. 2006

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Abstract. The substorm associated behavior of the low energy particles (30 eV-28.5 keV) near the earthward edge of the plasma sheet is examined using data from CRRES during the late growth and early expansion phases of a substorm on 12 March 1991 and their significance for the substorm onset mechanism is discussed. In this substorm, the CRRES was located on L ∼6.3 and ∼20 • westward of the substorm onset and observed the sequence of the alternating bursts of the low energy ions and electrons. The bursts of the 0.633-9.6 keV ions occurred 1-2 min before the (7.31-21.7 keV) electron bursts. The first ion burst happened 2 min before the substorm onset, at the moment of weak brightening of the most equatorial pre-breakup arc near the latitude ∼62 • . The alternation of the ion and electron bursts may be a signature of a drift-Alfvén ballooning instability on the inner edge of the plasma sheet near substorm onset.

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Disruption of parallel current at substorm breakup

Cited by 19 publications

References 16 publications

First Results of the THEMIS Search Coil Magnetometers

First Results of the THEMIS Search Coil Magnetometers

Substorm expansion phase: Observations from Geotail, Polar and IMAGE network

Alternating bursts of low energy ions and electrons near the substorm onset

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