The Electron Drift Instrument on Cluster: overview of first results

Paschmann, G.; Quinn, J. M.; Torbert, R. B.; Vaith, H.; McIlwain, C. E.; Haerendel, G.; Bauer, O. H.; Bauer, Thomas; Baumjohann, W.; Fillius, W.; Förster, M.; Frey, S.; Georgescu, E.; Kerr, S. S.; Kletzing, C. A.; Matsui, H.; Puhl-Quinn, P.; Whipple, E. C.

doi:10.5194/angeo-19-1273-2001

Cited by 97 publications

(94 citation statements)

References 16 publications

(10 reference statements)

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“…The Electric Fields and Waves experiment (EFW) (Gustafsson et al, 1997(Gustafsson et al, , 2001) and the Electron Drift Instrument (EDI) (Paschmann et al, 2001) are designed to measure the electric field directly. In addition, the drift of low energy plasma ions as detected by the Cluster Ion Spectrometer (CIS) (Rème et al, 2001) can be used to estimate the electric field on the assumption that the E×B drift is dominant.…”

Section: Current Density and Electric Fieldmentioning

confidence: 99%

Occurrence and location of concentrated load and generator regions observed by Cluster in the plasma sheet

et al. 2009

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Abstract.Here, and in a companion paper by Hamrin et al. (2009) [Scale size and life time of energy conversion regions observed by Cluster in the plasma sheet], we investigate localized energy conversion regions (ECRs) in the Earth's plasma sheet. In total we have studied 151 ECRs within 660 h of plasma sheet data from the summer and fall of 2001 when Cluster was close to apogee at an altitude of about 15-20 R E . Cluster offers appropriate conditions for the investigation of energy conversion by the evaluation of the power density, E·J , where E is the electric field and J the current density. From the sign of the power density, we have identified more than three times as many Concentrated Load Regions (CLRs) as Concentrated Generator Regions (CGRs). We also note that the CLRs appear to be stronger. To our knowledge, these are the first in situ observations confirming the general notion of the plasma sheet, on the average, behaving as a load. At the same time the plasma sheet appears to be highly structured, with energy conversion occurring in both directions between the fields and the particles. From our data we also find that the CLRs appear to be located closer to the neutral sheet, while CGRs prefer locations towards the plasma sheet boundary layer (PSBL). For both CLRs and CGRs, E and J in the GSM y (cross-tail) direction dominate the total power density, even though the z contribution occasionally can be significant. The prevalence of the y-direction seems to be weaker for the CGRs, possibly related to a higher fluctuation level near the PSBL.

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Section: Current Density and Electric Fieldmentioning

confidence: 99%

Occurrence and location of concentrated load and generator regions observed by Cluster in the plasma sheet

et al. 2009

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“…[10] The in situ measurements from the fluxgate magnetometers (FGM) [Balogh et al, 2001], the Electron Drift Instrument (EDI) [Paschmann et al, 2001], and the Electric Field and Wave (EFW) Experiment [Gustafsson et al, 2001] on board Cluster are also used.…”

Section: Instrumentation: Clustermentioning

confidence: 99%

Shock-driven variation in ionospheric outflow during the 11 October 2001 moderate storm

et al. 2011

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[1] The Composition and Distribution Function (CODIF) Analyzer on board the Cluster spacecraft frequently observes narrow-energy, field-aligned O + ions over the polar caps and in the lobes, particularly during storm times. This population is due to ion outflow from the cusp. During the 11 October 2001 moderate storm, CODIF, located in the southern lobe at ∼12 Earth radii (R E ) down the tail and moving inbound, observed a change in the outflow. A sudden increase in solar wind dynamic pressure at 1702 UT led to a sudden increase in the energy of peak O + flux from ∼0.2 to 5 keV or an abrupt increase in parallel velocity from 54.0 ± 3.8 to 212.5 km/s. This high-energy population gradually decreased in energy over the next ∼2 h. The energy increase resulted from the effects of the solar wind shock on preexisting outflow. To model the effects of the shock, we first determined how the magnetic field configuration changed, by comparing the local magnetic field before and after the shock with the predictions of the T04s empirical model. The local field, reasonably well reproduced by T04s, experienced a 0.8-R E perpendicular displacement and a first 8.3°then 0.9°rotation in 3.8 min when the solar wind shock hit. We used local measurements of the H + drift velocity and magnetic field to calculate if the observed velocity increase was due to centrifugal acceleration. We found that at the beginning centrifugal acceleration contributed only 11.4%, i.e., 18.0 km/s, to the sudden O + parallel velocity increase; the net effect of the centrifugal acceleration is against the velocity increase. We conclude that the increase was actually due to the field displacement, which brought a higher velocity population to the Cluster location. A higher velocity is expected at higher latitudes due to the velocity filter effect that results from higher-energy ions moving further along the field line than lower-energy ions, as the field line convects over the polar cap and into the tail.

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“…Those directions are uniquely determined by both the magnetic field and plasma drift magnitude and direction, assuming that the drift due to magnetic field gradients can be neglected. The drift velocity is then estimated either from the direction of the beam via simple triangulation or from their differences in timesof-flight (for more details see Paschmann et al, 1997Paschmann et al, , 2001Quinn et al, 2001).…”

Section: Cluster Edi Datamentioning

confidence: 99%

High-latitude plasma convection during Northward IMF as derived from in-situ magnetospheric Cluster EDI measurements

et al. 2008

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Abstract. In this study, we investigate statistical, systematic variations of the high-latitude convection cell structure during northward IMF. Using 1-min-averages of Cluster/EDI electron drift observations above the Northern and Southern polar cap areas for six and a half years (February 2001 till July 2007, and mapping the spatially distributed measurements to a common reference plane at ionospheric level in a magnetic latitude/MLT grid, we obtained regular drift patterns according to the various IMF conditions. We focus on the particular conditions during northward IMF, where lobe cells at magnetic latitudes >80 • with opposite (sunward) convection over the central polar cap are a permanent feature in addition to the main convection cells at lower latitudes. They are due to reconnection processes at the magnetopause boundary poleward of the cusp regions. Mapped EDI data have a particular good coverage within the central part of the polar cap, so that these patterns and their dependence on various solar wind conditions are well verified in a statistical sense. On average, 4-cell convection pattern are shown as regular structures during periods of nearly northward IMF with the tendency of a small shift toward negative clock angles. The positions of these high-latitude convection foci are within 79 • to 85 • magnetic latitude and 09:00-15:00 MLT. The MLT positions are approximately symmetric ±2 h about 11:30 MLT, i.e. slightly offset from midday toward prenoon hours, while the maximum (minimum) potential of the high-latitude cells is at higher magnetic latitudes near their maximum potential difference at ≈−10 • to −15 • clock angle for the North (South) Hemisphere. With increasing clock angle distances from ≈IMFB z +, a gradual transition occurs from the 4-cell pattern via a 3-cell to the Correspondence to: M. Förster (mfo@gfz-potsdam.de) common 2-cell convection pattern, in the course of which one of the medium-scale high-latitude dayside cells diminishes and disappears while the other intensifies and merges with the opposite main cell of the same polarity to form the large "round-shaped" convection cell when approaching a well-known IMFB y -dominated configuration. Opposite scenarios with interchanged roles of the respective cells occur for the opposite turning of the clock angle and at the Southern Hemisphere. The high-latitude dayside cells become more pronounced with increasing magnitude of the IMF vector.

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The Electron Drift Instrument on Cluster: overview of first results

Cited by 97 publications

References 16 publications

Occurrence and location of concentrated load and generator regions observed by Cluster in the plasma sheet

Occurrence and location of concentrated load and generator regions observed by Cluster in the plasma sheet

Shock-driven variation in ionospheric outflow during the 11 October 2001 moderate storm

High-latitude plasma convection during Northward IMF as derived from in-situ magnetospheric Cluster EDI measurements

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