One of the important effects of the ionospheric modification by high-power waves is the airglow enhancement. Both the thermal electrons and the dissociation recombination contribute to generate the airglow emissions d...One of the important effects of the ionospheric modification by high-power waves is the airglow enhancement. Both the thermal electrons and the dissociation recombination contribute to generate the airglow emissions during HF heating. However, the relative importance of the airglow emission induced by dissociative recombination and thermal electrons has been rarely investigated. In this study, we carry out a simulation study on the airglow produced by high-power HF heating at nighttime associated with dissociative recombination and thermal electrons. SAMI2(Sami2 is Another Model of the Ionosphere) is employed to simulate the ionospheric variations during the HF heating. The main conclusions from this study are as follows:(1) For the airglow induced by dissociative recombination, both 630.0 nm and 557.7 nm emissions show a decrease at the heating wave reflection height during the heating period,while when the heating is turned off, an increase is shown at lower altitudes. The reduction of airglow during the heating is caused by the rapid increase of electron temperature and the diffusion of plasmas dominates the after-heating airglow enhancement.(2) 630.0 nm emission due to thermal electrons is greatly enhanced at the wave reflection height, indicating that thermal electrons play a major role in exciting 630.0 nm emission. For the 557.7 nm emission, the excitation threshold(4.17 e V) is too high for thermal electrons.(3) The combined effect of dissociative recombination and thermal electrons could be the possible reason for the observed X-mode(extraordinary mode) suppression of 630.0 nm airglow during O-mode(ordinary mode) enhancement.展开更多
The propagation of HF waves in IAR can produce many nonlinear effects, including the modulation effect of IAR on HF waves and the Doppler effect. To start with the dependence of the ionospheric electron temperature va...The propagation of HF waves in IAR can produce many nonlinear effects, including the modulation effect of IAR on HF waves and the Doppler effect. To start with the dependence of the ionospheric electron temperature variations on the Alfvén resonant field, We discuss the mechanism of the modulation effect and lucubrate possible reasons for the Doppler effect. The results show that the Alfvén resonant field can have an observable modulation effect on HF waves while its mechanism is quite different from that of Schumann resonant field on HF waves. The depth of modulation of IAR on HF waves has a quasi\|quadratic relation with the Alfvén field, which directly inspires the formation of cross\|spectrum between ULF waves and HF waves and results in spectral peaks at some gyro\|frequencies of IAR. With respect to the Doppler effect during the propagation of HF waves in IAR, it is mainly caused by the motion of the high\|speed flyer and the drifting electrons and the frequency shift from the phase variation of the reflected waves can be neglected when the frequency of HF incident wave is high enough.展开更多
A numerical model has been developed.Based on the numerical simulation results,the spatial effects of the ionosphere,mainly consisting of the change on electron density(ED)and electron temperature(ET),heated by the hi...A numerical model has been developed.Based on the numerical simulation results,the spatial effects of the ionosphere,mainly consisting of the change on electron density(ED)and electron temperature(ET),heated by the high frequency(HF)pump wave have been analyzed quantitatively.Results are presented as the space-time evolution regulation on the main parameters of the ionosphere resulted by the HF heating waves under the different heat-conditions,just as different regions,such as high latitude and mid-low latitude;different heating power or frequency,such as underdense heating and over-dense heating and regions at different altitudes.The heating effects in different regions with different heating conditions have been presented in figures.Finally,some primary conclusions are given by comparing the simulation results with experimental observation.展开更多
基金supported by the National Natural Science Foundation of China(41325017,41274158,41274157,and 41421063)the fundamental research funds for the central universitiesThousand Young Talents Program of China
文摘One of the important effects of the ionospheric modification by high-power waves is the airglow enhancement. Both the thermal electrons and the dissociation recombination contribute to generate the airglow emissions during HF heating. However, the relative importance of the airglow emission induced by dissociative recombination and thermal electrons has been rarely investigated. In this study, we carry out a simulation study on the airglow produced by high-power HF heating at nighttime associated with dissociative recombination and thermal electrons. SAMI2(Sami2 is Another Model of the Ionosphere) is employed to simulate the ionospheric variations during the HF heating. The main conclusions from this study are as follows:(1) For the airglow induced by dissociative recombination, both 630.0 nm and 557.7 nm emissions show a decrease at the heating wave reflection height during the heating period,while when the heating is turned off, an increase is shown at lower altitudes. The reduction of airglow during the heating is caused by the rapid increase of electron temperature and the diffusion of plasmas dominates the after-heating airglow enhancement.(2) 630.0 nm emission due to thermal electrons is greatly enhanced at the wave reflection height, indicating that thermal electrons play a major role in exciting 630.0 nm emission. For the 557.7 nm emission, the excitation threshold(4.17 e V) is too high for thermal electrons.(3) The combined effect of dissociative recombination and thermal electrons could be the possible reason for the observed X-mode(extraordinary mode) suppression of 630.0 nm airglow during O-mode(ordinary mode) enhancement.
文摘The propagation of HF waves in IAR can produce many nonlinear effects, including the modulation effect of IAR on HF waves and the Doppler effect. To start with the dependence of the ionospheric electron temperature variations on the Alfvén resonant field, We discuss the mechanism of the modulation effect and lucubrate possible reasons for the Doppler effect. The results show that the Alfvén resonant field can have an observable modulation effect on HF waves while its mechanism is quite different from that of Schumann resonant field on HF waves. The depth of modulation of IAR on HF waves has a quasi\|quadratic relation with the Alfvén field, which directly inspires the formation of cross\|spectrum between ULF waves and HF waves and results in spectral peaks at some gyro\|frequencies of IAR. With respect to the Doppler effect during the propagation of HF waves in IAR, it is mainly caused by the motion of the high\|speed flyer and the drifting electrons and the frequency shift from the phase variation of the reflected waves can be neglected when the frequency of HF incident wave is high enough.
基金supported by the Hi-Tech Research and Development Program of China(No.2004733AA101).
文摘A numerical model has been developed.Based on the numerical simulation results,the spatial effects of the ionosphere,mainly consisting of the change on electron density(ED)and electron temperature(ET),heated by the high frequency(HF)pump wave have been analyzed quantitatively.Results are presented as the space-time evolution regulation on the main parameters of the ionosphere resulted by the HF heating waves under the different heat-conditions,just as different regions,such as high latitude and mid-low latitude;different heating power or frequency,such as underdense heating and over-dense heating and regions at different altitudes.The heating effects in different regions with different heating conditions have been presented in figures.Finally,some primary conclusions are given by comparing the simulation results with experimental observation.
