Preliminary Report of Numerical Simulations of Intermediate Wavelength Collisional Rayleigh-Taylor Instability in Equatorial Spread F

摘要

Computer simulations of the intermediate wavelength (100-1000 m) collisional Rayleigh-Taylor instability have been performed using parameters typical of the post-sunset bottomside (300 km) equatorial F region ionosphere. For ambient electron density gradient scale lengths L = 5, 10, 15 km we find that the linearly unstable modes saturate by nonlinear generation of linearly damped vertical modes with the result that in the nonlinear regime power laws are observed in the horizontal P(k sub x) varies as k sub x to the minus nth power and vertical P(k sub y) varies as k sub y to the minus nth power one-dimensional power spectra with n = 2-2.5. These results are consistent both with in situ experimental data and theoretical prediction.