The Double Star Plasma Electron and Current Experiment

Fazakerley, A. N.; Carter, P. J.; Watson, G.; Spencer, A. P.; Sun, Yueqiang; Coker, J.; Coker, Phil; Kataria, D. O.; Fontaine, Dominique; Liu, Z. X.; Gilbert, L. K.; He, L. H.; Lahiff, A. D.; Mihalčič, B.; Szita, S.; Taylor, Matt; Wilson, R.; Dedieu, M.; Schwartz, Steven J.

doi:10.5194/angeo-23-2733-2005

Cited by 39 publications

(33 citation statements)

References 16 publications

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“…The field-of-view of each analyser covers 180 • , divided into 12 polar zones, 15 • wide, relative to the spin axis. The azimuthal coverage of the 3-D distributions is achieved by spin rotation (Johnstone et al, 1997;Fazakerley et al, 2005). At altitudes of 5-9 R E over the polar cap, the plasma is generally tenuous and the spacecraft potential ϕ sat can reach as high values as ∼40 Volts which accelerates the electrons.…”

Section: Observationsmentioning

confidence: 99%

“…For the electrons, the moments are generally computed onboard from the integration of averaged 3-D distribution functions provided by PEACE over given energy windows (Fazakerley et al, 2005). For observations above the polar cap where the plasma is often very tenuous, the spacecraft potential increases and the photoelectron energy range may reach several tens of eV.…”

Section: Current Densitymentioning

confidence: 99%

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CLUSTER observations of electron outflowing beams carrying downward currents above the polar cap by northward IMF

Teste¹,

Fontaine²,

Sauvaud

et al. 2007

Ann. Geophys.

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Abstract. Above the polar cap, at about 5-9 Earth radii (R E ) altitude, the PEACE experiment onboard CLUSTER detected, for the first time, electron beams outflowing from the ionosphere with large and variable energy fluxes, well collimated along the magnetic field lines. All these events occurred during periods of northward or weak interplanetary magnetic field (IMF).These outflowing beams were generally detected below 100 eV and typically between 40 and 70 eV, just above the photoelectron level. Their energy gain can be explained by the presence of a field-aligned potential drop below the spacecraft, as in the auroral zone. The careful analysis of the beams distribution function indicates that they were not only accelerated but also heated. The parallel heating is estimated to about 2 to 20 eV and it globally tends to increase with the acceleration energy. Moreover, WHISPER observed broadband electrostatic emissions around a few kHz correlated with the outflowing electron beams, which suggests beam-plasma interactions capable of triggering plasma instabilities.In presence of simultaneous very weak ion fluxes, the outflowing electron beams are the main carriers of downward field-aligned currents estimated to about 10 nA/m 2 . These electron beams are actually not isolated but surrounded by wider structures of ion outflows. All along its polar cap crossings, Cluster observed successive electron and ion outflows. This implies that the polar ionosphere represents a significant source of cold plasma for the magnetosphere during northward or weak IMF conditions. The successive ion and electron outflows finally result in a filamented current system of opposite polarities which connects the polar ionosphere to distant regions of the magnetosphere.

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Section: Observationsmentioning

confidence: 99%

Section: Current Densitymentioning

confidence: 99%

CLUSTER observations of electron outflowing beams carrying downward currents above the polar cap by northward IMF

Teste¹,

Fontaine²,

Sauvaud

et al. 2007

Ann. Geophys.

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“…Here the mean field axis points out of the page, so an anticlockwise rotation of the field vectors with time on the plot represents the effect of a parallel current and vice versa. Panels (e-g) are energy-time spectrograms for electrons with pitch angles of 0 • , 90 • and 180 • , respectively, as measured by the PEACE instrument on board TC-2 (Fazakerley et al, 2005). It should be noted that because the Double Star PEACE instrument has one sensor, rather than the two that make up each Cluster instrument, a distribution covering the full energy range is accumulated every two spins (i.e.…”

Section: Double Star Tc-2 Observationsmentioning

confidence: 99%

Cluster and Double Star multipoint observations of a plasma bubble

et al. 2009

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Abstract. Depleted flux tubes, or plasma bubbles, are one possible explanation of bursty bulk flows, which are transient high speed flows thought to be responsible for a large proportion of flux transport in the magnetotail. Here we report observations of one such plasma bubble, made by the four Cluster spacecraft and Double Star TC-2 around 14:00 UT on 21 September 2005, during a period of southward, but B Y -dominated IMF. In particular the first direct observations of return flows around the edges of a plasma bubble, and the first observations of plasma bubble features within 8 R E of the Earth, consistent with MHD simulations (Birn et al., 2004) are presented. The implications of the presence of a strong B Y in the IMF and magnetotail on the propagation of the plasma bubble and development of the associated current systems in the magnetotail and ionosphere are discussed. It is suggested that a strong B Y can rotate the field aligned current systems at the edges of the plasma bubble away from its duskward and dawnward flanks.

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“…Cluster and Double Star observations of the local magnetic field, ion and electron populations employed in this study are provided by the fluxgate magnetometer (FGM; see Balogh et al, 1997Balogh et al, , 2001Carr et al, 2005), Cluster ion spectrometry (CIS; see Rème et al, 1997Rème et al, , 2001Rème et al, , 2005, and plasma electron and current (PEACE: see Johnstone et al, 1997;Owen et al, 2001;Fazakerley et al, 2005) experiments, respectively. The FGM data have been analysed at a temporal resolution equal to the spin period of the spacecraft (∼4 s for both Cluster and Double Star).…”

Section: Instrumentationmentioning

confidence: 99%

On the location of dayside magnetic reconnection during an interval of duskward oriented IMF

et al. 2007

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Abstract. We present space-and ground-based observations of the signatures of magnetic reconnection during an interval of duskward-oriented interplanetary magnetic field on 25 March 2004. In situ field and plasma measurements are drawn from the Double Star and Cluster satellites during traversals of the pre-noon sector dayside magnetopause at low and high latitudes, respectively. These reveal the typical signatures of flux transfer events (FTEs), namely bipolar perturbations in the magnetic field component normal to the local magnetopause, enhancements in the local magnetic field strength and mixing of magnetospheric and magnetosheath plasmas. Further evidence of magnetic reconnection is inferred from the ground-based signatures of pulsed ionospheric flow observed over an extended interval. In order to ascertain the location of the reconnection site responsible for the FTEs, a simple model of open flux tube motion over the surface of the magnetopause is employed. A comparison of the modelled and observed motion of open flux tubes (i.e. FTEs) and plasma flow in the magnetopause boundary layer indicates that the FTEs observed at both low and high latitudes were consistence with the existence of a tilted Xline passing through the sub-solar region, as suggested by the component reconnection paradigm. While a high latitude Xline (as predicted by the anti-parallel description of reconnection) may have been present, we find it unlikely that it could have been responsible for the FTEs observed in the pre-noon sector under the observed IMF conditions. Finally, we note that throughout the interval, the magnetosphere was bathed in ULF oscillations within the solar wind electric field. While no one-to-one correspondence with the pulsed reconnection rate suggested by the ground-based observation of pulsed Correspondence to: J. A. Wild (j.wild@lancaster.ac.uk) ionospheric flow has been demonstrated, we note that similar periodicity oscillations were observed throughout the solar wind-magnetosphere-ionosphere system. These findings are consistent with previously proposed mechanisms of solar wind modulation of the dayside reconnection rate.

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The Double Star Plasma Electron and Current Experiment

Cited by 39 publications

References 16 publications

CLUSTER observations of electron outflowing beams carrying downward currents above the polar cap by northward IMF

CLUSTER observations of electron outflowing beams carrying downward currents above the polar cap by northward IMF

Cluster and Double Star multipoint observations of a plasma bubble

On the location of dayside magnetic reconnection during an interval of duskward oriented IMF

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