Parallel Propagation Effects on the Type I Electrojet Instability.
NAVAL RESEARCH LAB WASHINGTON D C
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The Farley-Buneman instability has been extended to consider higher frequency, shorter wavelength modes thus including finite Debye length effects while allowing these modes to propagate with a component parallel to the magnetic field k parallel not 0. By driving the current sufficiently hard drift speeds in the range 2-3 times the ion thermal velocity, vi the growth rates of these modes maximize slightly away from the perpendicular to the magnetic field showing the importance of k parallel not 0. Although the wavelengths of these maximum growing modes are in the regime of several to tens of centimeters, the phase velocities are near the ion thermal velocity. This suggests that a nonlinear coupling of these off angle modes may be responsible for the observed radar spectrum with maximum intensity near vi and wavelengths in the 1-10 meter regime. Maximum growth rates of off angle propagation while varying the densities and collision frequencies are shown. Also, growth rates of unstable waves in the radar regime 1-10 meters are shown for drift velocities 1.5 and 3 times vi. Modified author abstract
- Atmospheric Physics