Whistler interactions with density gradients in the magnetosphere

Very-low frequency whistler-mode waves are frequently observed in the equatorial magnetosphere. Large amplitude whistlers, capable of rapidly accelerating electrons to large energies, are typically observed to propagate at highly oblique angles relative to the background magnetic field. In this paper, we discuss a potential mechanism for the conversion of moderately oblique whistlers to highly oblique whistlers on a transverse gradient of the background plasma. We offer a theoretical explanation for this process and illustrate its operation using numerical simulations. This effect has been previously observed in laboratory experiments and it also provides a straightforward explanation for observations of highly oblique whistlers in magnetospheric plasmas. Citation: Woodroffe, J. R., and A. V. Streltsov (2013), Whistler interactions with density gradients in the magnetosphere, J. Geophys. Res. Space Physics, 118, 167-172, doi:10.1029/2012JA018308.