Active Ionosphere Technology And Its Application In Sky Wave Radar

The study of active ionospheric technology will help to make full use of the role of the ionosphere and avoid the negative effects of ionospheric disturbance.Based on the EISCAT experimental data,the parametric instability excited by high-power HF radio waves heating the ionosphere is analyzed and studied in this paper.A three-dimensional kinetic model including the diffusion process of neutral chemical substances,ion chemical reaction process and plasma diffusion process is established,and the models of chemical substances under three different release paths of 300km fixed point,250km-350km vertical path and 250km-350km parabola path are established for the first time.The differences of ionospheric hole disturbances caused by different release paths are compared and analyzed.Then,by establishing a three-dimensional ray tracing model,this paper focuses on the influence of ionospheric disturbance caused by chemical release on the propagation path of shortwave signal whose frequency is in the frequency range of sky wave over-the-horizon radar.It is expected that in the follow-up research of sky-wave radar,it can make up for the deficiency of sky-wave radar detection under the condition of ionospheric disturbance,and provide simulation experimental data for improving the comprehensive detection performance of sky-wave radar.The results are as follows.1.Combining multiple experiments and analysis,it is verified that the electron density enhancement phenomenon within the range of the reflection height up to the radar detection limit distance（660km）is not a true increase in the electron density,but an apparent enhancement phenomenon of the ion spectrum line.2.In the ionospheric simulation of disturbance caused by the release of neutral chemicals,it is found that the electron density dissipation is the fastest and the dissipation degree is the largest at the peak height of the ionospheric electron density,the electron density gradient is the largest,and the disturbance radius of the ionospheric hole is also the largest.3.It is found that after 100s release of CO₂,the"secondary focusing effect"occurs when some of the short-wave rays of 8MHz are pierced at the top of the cavity,and there are two focal points.However,this phenomenon is accidental,and it disappears with the passage of time,and then there is only one focus.4.It is found that different release paths have different effects on the radio wave propagation:the focusing effect of the short wave passing through the ionospheric disturbance region is the strongest when the short wave is vertically released,followed by the fixed point release,and the focusing effect of the radio wave is the weakest in the case of parabolic release.