Study on the Evolutionary Process of Lower-hybrid Wave Excited by Neutral Gas Injection into the Ionosphere

This paper focuses on the study of the two-dimensional spatiotemporal evolution characteristics of lower hybrid wave excitation by neutral gas injection into the ionosphere. Using water vapor injection as an example, a theoretical model is established, and the theoretical expression for the growth rate of the lower hybrid wave is derived. Based on this, the two-dimensional evolution of parameters such as propagation direction and amplitude of the lower hybrid wave in the ionosphere after excitation is studied as a function of time and space. The results show that the ion ring beam distribution formed by the charge exchange between the high-speed injected water vapor and the ionospheric oxygen ions is the primary factor in the excitation of the lower hybrid wave. Its growth rate is significantly influenced by factors such as the diffusion rate of the water vapor, the background plasma density, and the release altitude. The research findings reveal the spatiotemporal characteristics of lower hybrid wave excitation and propagation in the ionosphere, providing a theoretical basis for understanding space plasma wave-particle interactions, energy transport processes, and the assessment of space artificial perturbation effects.