The Wave Experiment Consortium (WEC)

Pedersen, Å.; Cornilleau‐Wehrlin, N.; Porte, B. de la; Roux, A.; Bouabdellah, Abdel; Décréau, Pierrette; Lefeuvre, F.; Sené, F. X.; Gurnett, D. A.; Huff, R. L.; Gustafsson, G.; Holmgren, Gunnar; Woolliscroft, L. J. C.; Alleyne, H.; Thompson, J. A.; Davies, P. H. N.

doi:10.1007/978-94-011-5666-0_4

Cited by 24 publications

(12 citation statements)

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“…The magnetic and electric field measurements were made by the fluxgate magnetometer FGM [Balogh et al, 1997] and Electric Fields and Waves (EFW) instruments [Gustafsson et al, 1997], respectively. EFW is a part of Cluster Wave Consortium (WEC) [Pedersen et al, 1997], a suite of plasma wave instruments centrally controlled by the Digital Wave Processor (DWP) instrument [Woolliscroft et al, 1997]. The EFW instrument consists of two pairs of spherical probe sensors, each on a 44 m wire boom in the spin plane of the satellite.…”

Section: Data and Instrumentationmentioning

confidence: 99%

On the fine structure of dipolarization fronts

et al. 2014

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Measurements from the closely spaced Cluster spacecraft are used to study the structure of the magnetic and electric fields within the magnetic ramp of dipolarization fronts (DF) observed close to the neutral sheet and the midnight meridian (YGSM<3RE). The spacecraft separation was small enough (<300 km) to treat the magnetic ramp of the DF front as a planar structure as indicated from variance analysis. The finite value of the magnetic field along the minimum variance direction for the events studied indicates that the dipolarization front structure was distinct from a tangential discontinuity. In addition to the main increase of the magnetic field in the maximum variance component, strong oscillations were observed in the intermediate component. The presence of this oscillatory structure results in an expansion of the region in which a change of magnetic pressure occurs, the size of which is typically an ion Larmor radius or greater. This widening is important in maintaining the pressure balance at the edge of the DF. This phenomenon resembles observations of intense current sheets in the magnetotail and also laboratory experiments of current sheet formation, in which a similar widening of the ramp region has been observed. In this paper we argue against the idea that an electron temperature anisotropy, resulting in electron curvature currents, can explain the formation of the oscillatory structures observed at DFs. These oscillations can be explained as eigenmode waves of the plasma that propagate away from the disturbance (DF) that is moving at subsonic speeds. Oscillations observed within the magnetic ramp indicate field‐aligned currents that are expected to be associated with DF.

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Section: Data and Instrumentationmentioning

confidence: 99%

On the fine structure of dipolarization fronts

et al. 2014

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“…The time resolution allowed by the onboard data processing within the allocated bit rate of about 1 kbit/s in normal mode is typically about 1.5 s for the active mode and 2 s for the passive measurements. The duty cycle choosen within WEC allows are to collect two active spectra every 28 s in normal mode (see Pedersen et al, 1997). The instrument's overall sensitivity (averaged noise level) is about 2 10 −7 V/Hz− 1/2 .…”

Section: The Instrumentmentioning

confidence: 99%

Identification of natural plasma emissions observed close to the plasmapause by the Cluster-Whisper relaxation sounder

et al. 2001

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Abstract. We use the data collected by the Whisper instrument onboard the Cluster spacecraft for a first test of its capabilities in the identification of the natural plasma waves observed in the Earth' s magnetosphere. The main signatures observed at the plasma frequency, upper hybrid frequency, and electron Bernstein modes were often difficult to be reliably recognized on previous missions. We use here the characteristic frequencies provided by the resonances triggered by the relaxation sounder of Whisper to identify with good confidence the various signatures detected in the complex wave spectra collected close to the plasmapause. Coupled with the good sensitivity, frequency and time resolution of Whisper, the resonances detected by the sounder allow one to precisely spot these natural emissions. This first analysis seems to confirm the interpretation of Geos observations: the natural emissions observed in Bernstein modes above the plasma frequency, now widely observed onboard Cluster, are not modeled by a single Maxwellian electrons distribution function. Therefore, multi-temperature electron distribution functions should be considered.

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“…[2] Each of the four satellites of the Cluster space fleet carries a pair of mutually perpendicular long-boom antennas with spherical probes at their tips, each about 88 m tip to tip, located in the spin plane [Gustafsson et al, 1997]. Several wave experiments use these antennas at different frequencies, ranging from direct current up to about 580 kHz in passive as well as active modes of operation, within a coordinated consortium [Pedersen et al, 1997]. Since the behavior of such antennas is known to depend strongly on the frequency, their design is quite sophisticated in order to comply with the constraints of each experiment.…”

Section: Introductionmentioning

confidence: 99%

Modeling of Cluster's electric antennas in space: Application to plasma diagnostics

et al. 2005

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[1] The main characteristics of the long-boom electric antennas installed on board the Cluster satellites are derived from finite element modeling in a kinetic and isotropic space plasma, in the frequency range of about 1-100 kHz. The model is based on the surface charge distribution method in quasi-static conditions. The impedances of both types of antenna, i.e., the double-wire and the double-probe, are computed versus the frequency normalized with respect to the local plasma frequency and for several different Debye lengths. Most of the code outputs are checked using analytic estimations for better understanding of the involved physical mechanisms. As a by-product, the effective length of the double-probe antenna and the mutual impedance between the two antennas are computed by the code. It is shown that if it had been possible to implement such measurements on board, one would have been able not only to determine accurately the electric characteristics of the antennas but also to estimate the local plasma parameters. Nevertheless, an interesting feature predicted by the model has been checked recently in orbit by running a special mode of operation for testing the mutual impedance measurement. The preliminary results are globally consistent with the predictions, except that they suggest that our Maxwellian model for the electron distribution should be revised in order to explain the unexpected low-frequency response. After analysis of the electron flux measurements obtained simultaneously, it appears that a rough adjustment of the electron distribution with a two-component distribution allows us to account for the observations. Citation: Béghin, C., P. M. E. Décréau, J. Pickett, D. Sundkvist, and B. Lefebvre (2005), Modeling of Cluster's electric antennas in space: Application to plasma diagnostics, Radio Sci., 40, RS6008,

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The Wave Experiment Consortium (WEC)

Cited by 24 publications

References 0 publications

On the fine structure of dipolarization fronts

On the fine structure of dipolarization fronts

Identification of natural plasma emissions observed close to the plasmapause by the Cluster-Whisper relaxation sounder

Modeling of Cluster's electric antennas in space: Application to plasma diagnostics

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