Abstract
The WHISPER relaxation sounder that is onboard the four CLUSTER spacecraft has as its main scientific objectives to monitor the natural waves in the 2 kHz–80 kHz frequency range and, mostly, to determine the total plasma density from the solar wind down to the Earth's plasmasphere. To fulfill these objectives, the WHISPER uses the two long double sphere antennae of the Electric Field and Wave experiment as transmitting and receiving sensors. In its active working mode, the WHISPER works according to principles that have been worked out for topside sounding. A radio wave transmitter sends an almost monochromatic and short wave train. A few milliseconds after, a receiver listens to the surrounding plasma response. Strong and long lasting echoes are actually received whenever the transmitting frequencies coincide with characteristic plasma frequencies. Provided that these echoes, also called resonances, may be identified, the WHISPER relaxation sounder becomes a reliable and powerful tool for plasma diagnosis. When the transmitter is off, the WHISPER behaves like a passive receiver, allowing natural waves to be monitored. This paper aims mainly at the resonance identification process description and the WHISPER capabilities and performance highlighting.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
REFERENCES
Etcheto, J., de Feraudy, H., and Trotignon, J.G., Plasma resonance stimulation in space plasmas, Adv. Space Res. 1981, vol. 1, pp. 183–196.
DÉcrÉau, P.M.E., Fergeau, P., Krasnoselskikh, V., Leveque, M., Martin, Ph., Randriamboarison, O., Sene., F.X., Trotignon, J.G, Canu, P., and Mogensen, P.B., WHISPER, a resonance sounder and wave analyser: performances and perspectives for the CLUSTER mission, Space Sci. Rev., 1997, vol. 79, pp 157–193.
Thouvenin, J.P. and Trotignon, J.G., Automatic resonance recognition method in solar wind, Nuovo Ciment. Soc. Ital. Fis. C, 1980, vol. 3. pp. 696–710.
Trotignon, J.G., Etcheto., J., and Thouvenin, J.P., Automatic determination of the electron density measured by the relaxation sounder on board ISEE 1, J. Geophys. Res., 1986, vol. 91, pp. 4302–4320.
Trotignon, J.G., Décréau, P.M.E., Rauch, J.L., Randriamboarison, O., Krasnoselskikh, V., Canu, P., Alleyne, H., Yearb, K., Le Guirriec, E., Seran, H. C., Sene, F. X., Martin, Ph., Leveque, M., and Fergeauet, P., How to determine the thermal electron density and the magnetic field strength from the CLUSTER / WHISPER observations around the Earth, Ann. Geophysicae, 2001, vol. 19, pp. 1711–1720.
Chappell, C.R., Harris, K.K., and Sharp, G.W., The dayside of the plasmasphere, J. Geophys. Res., 1971, vol. 76, pp. 7632–7647.
Hamelin, M., Contribution á l'étude des ondesélectrostatiques et électromagnétiques au voisinage de la fréquence hybride basse dans le plasma ionosphérique, Thése de Doctorat dÈtat, Université d'Orléans, Orléans, France, 1978.
Etcheto, J., Belmont, G., Canu, P., and Trotignon, J. G., Active sounder experiments on GEOS and ISEE, ESA SP, 1983, vol. 195. pp. 39–46.
Belmont, G., Characteristic frequencies of a non-Maxwellian plasma: a method for localizing the exact frequencies of magnetospheric intense natural waves near f pe, Planet. Space Sci., 1981, vol. 29, pp. 1251–1266.
Canu, P., Observation of long-duration gyroharmonic resonances: a refutation of the short-duration explanation for interpreting the anomalous URAP sounder spectra observed in the Io torus, Radio Science, 2001, vol. 36, pp. 171–181.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Trotignon, J.G., Décréau, P.M.E., Rauch, J.L. et al. The Whisper Relaxation Sounder Onboard Cluster: A Powerful Tool for Space Plasma Diagnosis1, 2 around the Earth. Cosmic Research 41, 345–348 (2003). https://doi.org/10.1023/A:1025045308666
Issue Date:
DOI: https://doi.org/10.1023/A:1025045308666