On the altitude dependence of transversely heated O+ distributions in the cusp/cleft

M. Bouhram (1) , B. Klecker (1) , W. Miyake (2) , H. Rème (3) , J.-A. Sauvaud (3) , M. Malingre (4) , L. Kistler (5) , A. Blagau (1, 6)

1 MPE - Max-Planck-Institut für Extraterrestrische Physik
2 CRL - Communications Research Laboratory
3 CESR - Centre d'étude spatiale des rayonnements
4 CETP - Centre d'étude des environnements terrestre et planétaires
5 EOS Space Science Center [Durham]
6 ISS - Institute of Space Science [Bucharest-Măgurele]

The present paper focuses on the altitude dependence of oxygen ion conics in the dayside cusp/cleft region. Here, combining oxygen data from the Akebono, Interball-2 and Cluster satellites allows, for the first time, one to follow the global development of energetic (up to ~10keV) ion outflow over a continuous and broad altitude range up to about 5.5 Earth radii (RE). According to earlier statistical studies, the results are consistent with a height-integrated energization of ions at altitudes up to 3.5 RE. Higher up, the results inferred from Cluster observations put forward evidence of a saturation of both a transverse energization rate and ion gyroradii. We suggest that such results may be interpreted as finite perpendicular wavelength effects (a few tens of km) in the wave-particle interactions. To substantiate the suggestion, we carry out two-dimensional, Monte Carlo simulations of ion conic production that incorporate such effects and limited residence times due to the finite latitudinal extent of the heating region.

Domaines: Astrophysique [astro-ph]; Cosmologie et astrophysique extra-galactique [astro-ph.CO]; Physique des plasmas [physics.plasm-ph]

M. Bouhram, B. Klecker, W. Miyake, H. Rème, J.-A. Sauvaud, et al.. On the altitude dependence of transversely heated O+ distributions in the cusp/cleft. Annales Geophysicae, 2004, 22 (5), pp.1787-1798. ⟨10.5194/angeo-22-1787-2004⟩. ⟨hal-00158038⟩