Upper Limit on Radiation Belt Electron Fluxes Controlled by a Self‐Consistent Feedback From Chorus Waves

Abstract Electron fluxes vary widely in the Earth's outer radiation belt and represent an important hazard for satellites. Chorus waves are generated by anisotropic electrons and can accelerate or precipitate them into the atmosphere. Here, a Fokker‐Planck diffusion code is used to approximately simulate the self‐consistent evolution of both 0.03–1 MeV electron fluxes and chorus wave power, from initially low levels, during sustained low‐energy electron injections from the plasma sheet. This evolution results from wave‐driven quasi‐linear pitch‐angle, energy, and mixed electron diffusion, combined with wave power amplification through cyclotron resonance with electrons. A simple but reasonable proxy is used to model chorus wave growth in four separate frequency bands. Simulations demonstrate that after strong and sustained low‐energy electron injections, 0.03–1 MeV electron fluxes stabilize at a self‐consistent upper limit, close to the Kennel‐Petschek limit. However, the exact shape in energy of this self‐consistent upper limit corresponds to the steady‐state attractor of the dynamical electron flux/wave power system in the presence of both pitch‐angle and energy diffusion, self‐consistently described by Fokker‐Planck and linear chorus wave power gain equations. We show that the characteristics of this self‐consistent upper limit weakly depend on initial parameters, and align well with Van Allen Probes observations.