Energetic particle injections into the outer cusp during compression events.

Dominique C. Delcourt (1) , H. V. Malova (2, 3) , L. M. Zelenyi (2) , J.-A. Sauvaud (4) , T. E. Moore (5) , M.-C. Fok (5)

1 CETP - Centre d'étude des environnements terrestre et planétaires
2 IKI - Space Research Institute of the Russian Academy of Sciences
3 SINP - D.V. Skobeltsyn Institute of Nuclear Physics
4 CESR - Centre d'étude spatiale des rayonnements
5 GSFC - NASA Goddard Space Flight Center

We investigate the dynamics of charged particles in the dayside magnetosphere in response to abrupt variations of the solar wind dynamical pressure. Using test particle simulations, we show that the electric field induced by the compression of the frontside magnetosphere may be responsible for prominent energization of plasma sheet ions as well as trapping at high latitudes. We demonstrate that, due to the short-lived character of the magnetic field line reconfiguration (on the time scale of a few minutes), the particle magnetic moment (first adiabatic invariant) may not be conserved during such events. Ions that are initially bouncing from one hemisphere to the other are found to experience nonadiabatic energization up to the hundred of keV range while being injected into the outer cusp. Such injections involve particles from limited portions of the dayside flux tubes. The energetic particles that are produced in the outer cusp during such events subsequently circulate about the field minimum at high latitudes without intercepting the equatorial plane, thus contributing to the high-energy populations that are observed in this region of space.

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

Dominique C. Delcourt, H. V. Malova, L. M. Zelenyi, J.-A. Sauvaud, T. E. Moore, et al.. Energetic particle injections into the outer cusp during compression events.. Earth Planets and Space, 2005, 57, pp.125-130. ⟨hal-00156445⟩