The quasi-electrostatic mode of chorus waves and electron nonlinear acceleration

International audienceSelected Time History of Events and Macroscale Interactions During Substorms observationsat medium latitudes of highly oblique and high-amplitude chorus waves are presented and analyzed. Thepresence of such very intense waves is expected to have important consequences on electron energizationin the magnetosphere. An analytical model is therefore developed to evaluate the efficiency of the trappingand acceleration of energetic electrons via Landau resonance with such nearly electrostatic chorus waves.Test-particle simulations are then performed to illustrate the conclusions derived from the analytical model,using parameter values consistent with observations. It is shown that the energy gain can be much largerthan the initial particle energy for 10 keV electrons, and it is further demonstrated that this energy gain isweakly dependent on the density variation along field lines