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Shapiro & Ride 1994
Shapiro, V.D. and Ride, S.K. (1994). Nonlinear effects involving whistler wave propagation in the magnetosphere. Journal of Geophysical Research 99: doi: 10.1029/94JA00718. issn: 0148-0227.

We consider nonlinear effects associated with the propagation of a quasi-monochromatic whistler wave packet along the inhomogeneous geomagnetic field. We show that under the specific conditions of the Siple experiment the whistler packet is subject to the modulational instability, resulting in longitudinal and transverse modulation of the envelope amplitude and the excitation of quasi-neutral density perturbations akin to ion acoustic waves. In particular, we examine the behavior of the wave packet in the vicinity of the region where the group velocity of the packet is a maximum. In general, the wave packet is subject to the competing effects of dispersive broadening and the nonlinear tendency to steepen. In the vicinity of the region of interest the dispersive broadening is small, and the tendency for steepening prevails. This results in the creation of anomalously narrow solitary waves. We analyze the situation analytically using a modification of the nonlinear Schrodinger equation. We evaluate the conditions required for the onset of the modulational instability and find its typical growth rate. We then construct nonlinear traveling wave solutions. These take the form of solitons, which move toward the rear edge of the wave packet. Because the dispersive effects are small, these solitons are narrow structures with steep boundaries. We then analyze the possibility that these solitons act as drivers for triggered emission. The interaction of resonant particles with the wave at the soliton leads to particle bunching in velocity. The resulting current serves as a source term for monochromatic radiation, the frequency of which changes with time as the bunches move in the inhomogeneous geomagnetic field. ¿ American Geophysical Union 1994

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Abstract

Keywords
Magnetospheric Physics, Plasma waves and instabilities, Space Plasma Physics, Kinetic and MHD theory, Space Plasma Physics, Nonlinear phenomena, Space Plasma Physics, Wave-particle interactions
Journal
Journal of Geophysical Research
http://www.agu.org/journals/jb/
Publisher
American Geophysical Union
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