Simulations on the electron dynamics in excitation of whistler mode waves with Dipole Research EXperiment (DREX) parameters

Chorus waves are widely investigated in space physics due to their significant role played in the radiation belts. Multiple structures of chorus frequency chirping elements, such as rising-tone structure, falling-tone structure, and hook-like structure, are observed in both space plasmas and the ground simulation experiments. In this paper, the numerical simulation on the generation of descending elements of chorus waves with parameters of a launching device, Dipole Research EXperiment, is conducted by a hybrid code named DAWN. The descending element of chorus waves is self-consistently generated without additional requirements except for a hot electron component as the free energy source. A case of ascending element under the magnetosphere parameters is also carried out to verify our simulations. Phase space distributions of electrons for the two chirping structures are analyzed, and the simulation results are consistent with previous theoretical predictions. It is obtained from the simulation results that the ascending element of chorus is observed together with an electron phase space hole (a depleted distribution function), while the descending elemet is observed together with an electron phase space clump. Published under license by AIP Publishing.