Hydromagnetic wave propagation and coupling in a magnetotail waveguide

摘要: For some time the magnetotail has been considered as a possible region where hydromagnetic waves can propagate waveguide modes. Recently, attention turned to magnetospheric flanks waveguides, and much useful insight gained into propagation of fast modes there, structure field line resonances they drive. We return investigate wave coupling in waveguide. This problem is significantly different from flank ambient magnetic directed along rather than across. Field type are not lobe describe numerical simulation model which Alfven speed decreases across central plasma sheet. The stimulated by short compressional perturbation located far tail. cross-tail spatial chosen give relatively weak between so that phase group velocities uncoupled be used interpret results. find propagates dispersively down form Fourier components with small parallel wavenumber contain most energy, slowly toward “Earth.” These act moving sources launch continuously earthward. dispersion relations such couple only limited transverse gradient. travel at local each line, on given becomes increasingly out adjacent lines. mixing our novel it includes effects gradients both frequency tend cancel other out. Nevertheless, phase-mixing process leads fine progress results likely applicable regions sheet boundary layer mantle.