Chorus Element Repetition: Roles of Energetic Electron Injection and Nonlinear Wave Growth

Abstract Chorus waves are coherent whistler‐mode emissions in Earth’s magnetosphere and play a key role in the acceleration and loss of radiation belt electrons. Their spectra commonly consist of discrete and repetitive elements, yet the mechanism governing this repetition is not fully understood. Using typical magnetospheric plasma parameters, we perform simulations to investigate the excitation of repetitive chorus elements. The repetition period is quantified and its dependence on plasma parameters and the background magnetic‐field configuration is examined. The results identify two factors controlling chorus element repetition: external energetic‐electron injection and intrinsic nonlinear wave growth. Energetic‐electron injection replenishes free energy, whereas nonlinear growth converts this free energy into wave energy. Specifically, the repetition period increases with the electron injection timescale but decreases with the nonlinear growth rate. Standardized regression coefficients indicate a slightly stronger influence of nonlinear wave growth on the repetition period.