Numerical simulation of ionospheric modification by three representative chemical releases

Artificial ionospheric modification can disturb the short-wave communications and satellite communications. In this paper, on the basis of neutral gas diffusion equation, chemical reaction equation and plasma diffusion equation, the ionospheric disturbances caused by three representative chemicals (H₂, CO₂, CF₃Br) are simulated with a 3D dynamics model. The short wave propagation in disturbed ionosphere is also investigated with a 3D digital ray tracing method. The results show that single-point releases generate ellipse-like ionospheric holes, and a slightly larger scale is found along magnetic field than vertical direction in the hole's horizontal plane. With the same amount of substance and same release altitude, H₂ diffuses fastest and CF₃Br diffuses slowest, but as for the maximum relative change rate of electron density at t=100 s, CF₃Br corresponds to the highest rate while H₂ corresponds to the lowest. The release of CF₃Br results in the smallest vertical range of ionospheric hole, so the ray firstly penetrating the hole is at a higher frequency than that of CO₂ and CF₃Br. The release of H₂ results in the smallest electron density gradient at the hole's boundary among three chemicals, so the altitude of ray focus point is always higher than that of CO₂ and CF₃Br, indicating the weakest focus effect. Multipoint releases generate parabola-like tubular holes and lead to more diverse ray paths as well as ray focus effect. The altitude of focus point elevates with higher ray frequency, which is consistent with the single-point release condition.