TEMPORAL EVOLUTION OF HF-EXCITED PLASMA-WAVES, MEASURED AT DIFFERENT PUMP FREQUENCIES BY STIMULATED ELECTROMAGNETIC EMISSION (SEE)

Experimental results concerning the growth and decay times of differen t spectral components of stimulated electromagnetic emission (SEE) are presented. A new method of measurement, employing a special pulsed pu mp scheme for the ionospheric plasma modification, has been elaborated and applied for studying HE-induced processes with high time resoluti on. The measurements performed show that the development and relaxatio n of different SEE features have an intricate pattern which depends on the emission frequency shift from the pump frequency, on the proximit y of the pump frequency to the gyroharmonic frequencies, on the intens ity of artificial ionospheric turbulence, and on the ionospheric condi tions. The scope of this method for studies of HF plasma turbulence is discussed. (C) 1997 Elsevier Science Ltd.