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Ann. Geophys., 16, 1251-1258, 1998
www.ann-geophys.net/16/1251/1998/
© European Geosciences Union 1998
Computer simulations for direct conversion of the HF electromagnetic wave into the upper hybrid wave in ionospheric heating experiments
H. O. Ueda1, Y. Omura2, and H. Matsumoto2
1Department of Urban Environment and Systems, Chiba University 1-33 Yayoi, Inage, Chiba 263, Japan
2Radio Atmospheric Science Center, Kyoto University Uji, Kyoto 611, Japan
Abstract. Excitation of upper hybrid waves associated
with the ionospheric heating experiments is assumed to be essential in
explaining some of the features of stimulated electromagnetic emissions (SEE). A
direct conversion process is proposed as an excitation mechanism of the upper
hybrid waves where the energy of an obliquely propagating electromagnetic pump
wave is converted into the electrostatic upper hybrid waves due to small-scale
density irregularities. We performed electromagnetic particle-in-cell
simulations to investigate the energy conversion process in the ionospheric
heating experiments. We studied dependence of the amplitude of the excited wave
on the propagation angle of the pump wave, scale length of the density
irregularity, degree of the irregularity, and thermal velocity of the plasma.
The maximum amplitude is found to be 37 of the pump amplitude under an optimum
condition.
Key words. Ionosphere (ionospheric irregularities;
plasma waves and instabilities; wave-particle interactions).
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