WHISPER, A Resonance Sounder and Wave Analyser: Performances and Perspectives for the Cluster Mission

Décréau, Pierrette; Fergeau, P.; Krannosels’Kikh, V.; Lévèque, M.; Martin, Ph.; Randriamboarison, Orélien; Sené, F. X.; Trotignon, J. G.; Canu, P.; Mögensen, P. B.

doi:10.1007/978-94-011-5666-0_7

Cited by 119 publications

(145 citation statements)

References 32 publications

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“…The total electron density is 0.49 cm −3 using the observed distribution (interpolated into a rectangular grid) and 0.51 cm −3 for the model (superposition of two bi-Maxwellians). (At the beginning of the research described in this study, plasma wave data from the WHISPER instrument [Décréau et al, 1997] was examined, and we thought that it suggested a plasma frequency ∼6.5 kHz that was consistent with the above electron density ∼0.5 cm −3 . After the research was finished, the WHISPER data was reexamined and it was decided that a plasma frequency of ∼8-10 kHz was more consistent with the data.…”

Section: Observed Distribution Functionsmentioning

confidence: 91%

Multiple harmonic ULF waves in the plasma sheet boundary layer: Instability analysis

et al. 2010

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[1] Multiple-harmonic electromagnetic waves in the ULF band have occasionally been observed in Earth's magnetosphere, both near the magnetic equator in the outer plasmasphere and in the plasma sheet boundary layer (PSBL) in Earth's magnetotail. Observations by the Cluster spacecraft of multiple-harmonic electromagnetic waves with fundamental frequency near the local proton cyclotron frequency, W cp , were recently reported in the plasma sheet boundary layer by Broughton et al. (2008). A companion paper surveys the entire magnetotail passage of Cluster during 2003, and reports 35 such events, all in the PSBL, and all associated with elevated fluxes of counterstreaming ions and electrons. In this study we use observed pitch angle distributions of ions and electrons during a wave event observed by Cluster on 9 September 2003 to perform an instability analysis. We use a semiautomatic procedure for developing model distributions composed of bi-Maxwellian components that minimizes the difference between modeled and observed distribution functions. Analysis of wave instability using the WHAMP electromagnetic plasma wave dispersion code and these model distributions reveals an instability near W cp and its harmonics. The observed and model ion distributions exhibit both beam-like and ring-like features which might lead to instability. Further instability analysis with simple beam-like and ring-like model distribution functions indicates that the instability is due to the ring-like feature. Our analysis indicates that this instability persists over an enormous range in the effective ion beta (based on a best fit for the observed distribution function using a single Maxwellian distribution), b′, but that the character of the instability changes with b′. For b′ of order unity (for instance, the observed case with b′ ∼ 0.4), the instability is predominantly electromagnetic; the fluctuating magnetic field has components in both the perpendicular and parallel directions, but the perpendicular fluctuations are larger. If b′ is greatly decreased to about 5 × 10 −4 (by increasing the magnetic field), the instability becomes electrostatic. On the other hand, if b′ is increased (by decreasing the magnetic field), the instability remains electromagnetic, but becomes predominantly compressional (magnetic fluctuations predominantly parallel) at b′ ∼ 2. The b′ dependence we observe here may connect various waves at harmonics of the proton gyrofrequency found in different regions of space.

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Section: Observed Distribution Functionsmentioning

confidence: 91%

Multiple harmonic ULF waves in the plasma sheet boundary layer: Instability analysis

et al. 2010

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“…The wave sensors on each satellite consist of a boom-mounted threeaxis search coil magnetometer and four electric probes at the ends of four 42.5 m long booms in the spin plane (Escoubet et al, 1997a). Electric field spectrograms from 2 to 80 kHz are provided by the Waves of HIgh frequency and Sounder for Probing of Electron density by Relaxation (WHISPER) experiment (Décréau et al, 1997). Below 4 kHz, electric and magnetic spectra are provided by the Spatio-Temporal Analysis of Field Fluctuations (STAFF) experiment (Cornilleau-Wehrlin et al, 1997).…”

Section: Cluster Instruments and Data Products Usedmentioning

confidence: 99%

Cluster observations of mid-latitude hiss near the plasmapause

et al. 2004

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Abstract. In the vicinity of the plasmapause, around the geomagnetic equator, the four Cluster satellites often observe banded hiss-like electromagnetic emissions (BHE); below the electron gyrofrequency but above the lower hybrid resonance, from 2 kHz to 10 kHz. We show that below 4 kHz, these waves propagate in the whistler mode. Using the first year of scientific operations of WHISPER, STAFF and WBD wave experiments on Cluster, we have identified the following properties of the BHE waves: (i) their location is strongly correlated with the position of the plasmapause, (ii) no MLT dependence has been found, (iii) their spectral width is generally 1 to 2 kHz, and (iv) the central frequency of their emission band varies from 2 kHz to 10 kHz. All these features suggest that BHE are in fact mid-latitude hiss emissions (MLH). Moreover, the central frequency was found to be correlated with the K p index. This suggests either that these banded emissions are generated in a given f/f ce range, or that there is a K p dependent Doppler shift between the satellites and a possible moving source of the MLH.

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“…Several different points of view have been published on the relationship between the scale size of the magnetic ramp and that over which the change in potential is observed. Some studies (Eselevich et al, 1971;Balikhin et al, 1993;Formisano and Torbert, 1982;Formisano, 1982Formisano, , 1985Balikhin et al, 2002;Krasnosel'skikh, 1985;Leroy et al, 1982;Liewer et al, 1991;Scholer et al, 2003) have proposed that the spatial scale of electrostatic potential is of the same order or smaller than that of the magnetic ramp under some conditions. Such shocks have been observed in numerous experimental and numerical studies of quasi-perpendicular supercritical shocks.…”

Section: Introductionmentioning

confidence: 99%

Electric field scales at quasi-perpendicular shocks

et al. 2004

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Abstract. This paper investigates the short scale structures that are observed in the electric field during crossings of the quasi-perpendicular bow shock using data from the Cluster satellites. These structures exhibit large amplitudes, as high as 70 mVm −1 and so make a significant contribution to the overall change in potential at the shock front. It is shown that the scale size of these short-lived electric field structures is of the order of a few c/ω pe . The relationships between the scale size and the upstream Mach number and θ Bn are studied. It is found that the scale size of these structures decreases with increasing plasma β and as θ Bn → 90 • . The amplitude of the spikes remains fairly constant with increasing M a and appears to increase as θ Bn → 90 • .

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WHISPER, A Resonance Sounder and Wave Analyser: Performances and Perspectives for the Cluster Mission

Cited by 119 publications

References 32 publications

Multiple harmonic ULF waves in the plasma sheet boundary layer: Instability analysis

Multiple harmonic ULF waves in the plasma sheet boundary layer: Instability analysis

Cluster observations of mid-latitude hiss near the plasmapause

Electric field scales at quasi-perpendicular shocks

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