Modeling Kinetic Field Line Resonances in 3D Frequency and Time Domain Simulations

Field Line Resonances (FLRs) form as eigenmodes of Alfven waves between conductive ionospheric boundaries along geomagnetic field lines. When kinetic Alfven waves develop along FLRs, electron inertial effects can limit the width of the structure and lead to dispersive wave trains that can accelerate particles. Kinetic field line resonances (KFLRs) have been detected by the Van Allen Probes in conjunction with steep density gradients, but their evolution and dynamics have been insufficiently modeled.

A numerical 3D time domain model magnetosphere explores the structure of FLRs in an idealized two-fluid dipole scheme. A similar frequency domain model measures kinetic wave resonance frequency modulations. Calculations are performed in both frequency and time domains for comparison. A finite conductivity current sheet ionospheric boundary condition allows for Hall coupling between the shear Alfven and fast mode waves. Sub electron inertial length scales allow for realistic development of FLR kinetic effects. A simplified Landau damping schema is tested with the two-fluid model to probe possible wave train scattering. The model provides the framework for future investigations of kinetic plasma wave evolution dynamics.