Saturation Properties of Whistler Wave Instability in a Plasma With Two Electron Components

Saturation properties of whistler wave instability driven by electron temperature anisotropy in a plasma with two electron components are investigated using particle‐in‐cell (PIC) simulations. Most of the previous self‐consistent PIC simulations or quasi‐linear theory used a single bi‐Maxwellian distribution of electrons, which might apply to solar wind or magnetosheath. In the inner magnetosphere, however, there is frequently a cold and dense electron component, coexisting with a hot electron component. In this work, we investigate the relation between temperature anisotropy ( A ) and parallel plasma beta ( β ‖ ) at saturation. Our results agree well with the previous conclusion obtained from linear theory in most cases. However, We show that the inverse relation breaks when β ‖ is larger than certain value β ‖ , lim , beyond which A increases with increasing β ‖ . We also investigated the dependence of the saturation wave intensity on plasma beta and the initial linear growth rate and show that the saturation amplitude can be modeled as a function of the maximum initial linear growth rate even in a plasma with two electron components. Our results might be useful to couple the microscopic wave excitation process with macroscopic global energetic electron dynamics and to understand whistler wave excitation in the inner magnetosphere.