CONTROLLED IONOSPHERIC PRECONDITIONING AND STIMULATED ELECTROMAGNETIC-RADIATION

New results of stimulated electromagnetic emissions (SEE) from the HIP AS Observatory are reported. A novel hf heating sequence was used to f irst precondition the ionosphere, and SEE was then excited with low-am plitude test pulses. Through this approach, the nonlinear physics of S EE was studied. The correlation between small-scale field-aligned dens ity striations and SEE generation was demonstrated, and SEE was excite d at power density of 24 dB less than normally required. The results c ompare well with theoretical predictions of SEE generation via trapped upper hybrid oscillations decay and cavitation within striations.