Computer experiments for excitation mechanism of upshifted electromagnetic emission observed in ionospheric heating experiments

Abstract

AbstractThe component wave called the BUM (broad upshifted maximum) excited at the time of electromagnetic heating experiment of the ionosphere is seen on the higher‐frequency side band of the pump wave or its harmonics. Therefore, its excitation mechanism cannot be explained by a simple parametric instability. There fore, the mode instability theory based on the nonuniform density plasma has been proposed.In the present research, in reference to the theoretical prediction as a starting point of analysis of the excitation mechanism, computer experiments are carried out by means of the electromagnetic particle code. It was confirmed that the density nonuniformity of the plasma is important for the excitation of the BUM. Also, an excitation mechanism of the BUM conceivable from the computer experiment results is proposed.