Near‐relativistic electron acceleration by Landau trapping in time domain structures

Data from the Van Allen Probes have provided the first extensive evidence of nonlinear (as opposed to quasi‐linear) wave‐particle interactions in space with the associated rapid (less than a bounce period) electron acceleration to hundreds of keV by Landau resonance in the parallel electric field of time domain structures (TDSs) traveling at high speeds (~20,000 km/s). This observational evidence is supported by simulations and discussion of the source and spatial extent of the fast TDS. This result indicates the possibility that the electrostatic fields in TDS may generate the electron seed population for cyclotron resonance interaction with chorus waves to make higher‐energy electrons. Key Points Electrons are accelerated to near‐relativistic energies by traveling parallel electric fields Such acceleration is due to Landau trapping of electrons in time domain structures This acceleration occurs in the Van Allen radiation belts and in other solar system plasmas