THE CLUSTER INNER MAGNETOSPHERE CAMPAIGN - RESULTS OF EMW WAVES STUDY.

Abstract:

The Cluster Inner Magnetosphere Campaign (CIMC) was conceived to make targeted observations of the plasma wave modes and to investigate the wave-particle interactions that can result in the acceleration of electrons to very high (MeV) energies as well as scattering other particles into the loss cone. This presentation discusses results from the CIMC related to the dynamics of Equatorial Magnetosonic Waves (EMW). Cluster measurements were obtained within the EMW generation region enabling the identification of the observed proton ring distribution as the source of instability leading to the generation of EMW. The small spacecraft separation enabled two point observations of EMW within the wave coherency scale, and therefore to identify the wave dispersion directly from measurements. This dispersion is compared with analytical results. Finally the validity Chirikov resonance overlap criteria has been investigated and found to be consistent with the measurements. This latter result validates the current use of the quasi-linear approach in the modelling of EMW in spite of their discrete nature. Other results from the CIMC are also reviewed briefly.