Wave vector directions of whistler-mode chorus
Résumé
Whistler-mode chorus has been shown to play a significant role in acceleration of relativistic electrons in the outer Van Allen radiation belt. It can also propagate from its source region and influence large regions of the inner magnetosphere. Distribution of the wave energy density in the space of the wave vector directions is a crucial parameter for modeling of both the wave-particle interactions and wave propagation in the inner magnetosphere. We present a survey of observations of whistler-mode chorus emissions by the Plasma Wave Instrument on the Polar spacecraft in 1996 and 1997 together with a large data set obtained by the STAFF-SA instruments onboard the CLUSTER spacecraft. We show that highly oblique propagation needs to be considered in the radiation belt models.