Dependence ofWhistlerMode ChorusWave Generation on the Maximum Linear Growth Rate

摘要

Whistler mode chorus waves play a key role in controlling electron dynamics in Earth's inner magnetosphere. A criterion has been previously suggested whereby if the maximum value of the linear growth rate of whistler mode waves exceeds a certain critical bound, then fully nonlinear wave growth occurs and chorus waves are generated. This criterion corresponds to a boundary curve in (N_h∕N_0,A_T) space where N_h is the hot electron number density, N_0 is the cold electron number density, and A_T is the thermal anisotropy. Chorus waves are generated in the region above the boundary curve, while no chorus waves are generated below the boundary curve. In the present study, we make use of a recently published set of 36 particle simulations of chorus, and we thereby are able to confirm the validity of the criterion. It is expected that this simple concept of the theoretical boundary curve based on linear theory will be useful in guiding the choice of parameters in future simulations of chorus and also of practical use in interpreting experimental chorus wave data.