Computer simulations for direct conversion of the HF electromagnetic wave into the upper hybrid wave in ionospheric heating experiments

H O Ueda,H Matsumoto,Y Omura

doi:10.1007/s00585-998-1251-y

H O Ueda, H Matsumoto + Show 1 more

Open Access

https://doi.org/10.1007/s00585-998-1251-y

Copy DOI

Journal: Annales Geophysicae	Publication Date: Oct 31, 1998
Citations: 6	License type: cc-by

Affiliation: Kyoto Bunkyo University, Kyoto University

Abstract

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).

Highlights

Investigations of the interaction of a high-frequency powerful radio wave of O mode (L-O mode) polarization with the ionospheric F- region plasma show that secondary stimulated electromagnetic emissions (SEE) are generated in the heated ionospheric region (ThideÂ et al, 1989; Leyser et al, 1989, 1990, 1993, 1994)
The results of the present simulation should give an important clue for estimation of the eciency of the direct conversion (DC) process, but its validity as a generation mechanism of SEE has to be tested in a future ionospheric heating experiment accompanied by an in-situ measurement of the electrostatic waves in the ionosphere
We performed particle-in-cell simulations to investigate the possibility of the direct conversion process in the ionospheric heating experiments where the pump wave stimulates the SEE via the excitation of the ES waves

Summary

Introduction

Investigations of the interaction of a high-frequency powerful radio wave of O mode (L-O mode) polarization with the ionospheric F- region plasma show that secondary stimulated electromagnetic emissions (SEE) are generated in the heated ionospheric region (ThideÂ et al, 1989; Leyser et al, 1989, 1990, 1993, 1994). They are observed in the altitude range between the reection height of a pump wave and the level of the upper hybrid. In the fourth section, summary and concluding remarks are given

Theoretical model

Computer simulations

Findings

Discussions and conclusions