High-power high-frequency-induced Langmuir turbulence in the smooth ionosphere at Arecibo. I. Theoretical predictions for altitude-resolved plasma line radar spectra

This is the first of two papers comprising a theoretical and observational study of new, altitude-resolved, observations at Arecibo of Langmuir turbul ence induced in the ionosphere by a powerful high-frequency (hf) heater ope rated at very low duty cycles. As shown in paper II [Cheung , Phys. Plasmas 8, 802 (2001)], higher power enabled the first observation at Arecibo of t he well-developed decay-cascade features in the Thomson scatter radar power spectrum at the unmodified matching altitudes. New theoretical predictions are presented here for the parameters of these observations emphasizing th e altitude and pump power dependence of the radar spectra and the time depe ndence of the spectra from the decaying spectra following heater switch-off . Further details of the strong turbulence signatures from higher altitudes are also presented. At the lower matching altitudes the increase, with hf power, of the angular width of the well-developed decay-cascade spectrum al lows these spectral features to come into the view of the Arecibo radar. Th e favorable comparison of the simulation predictions and observations is di scussed in the second paper. (C) 2001 American Institute of Physics.