On the Nonlinear Plasma Waves in the High-Frequency Wave Heating of the Ionosphere

In the O-mode high-frequency (HF) heating of the ionosphere, parametric instabilities were excited to generate plasma waves. Among those, Langmuir waves and ion acoustic waves were evidenced by the HF enhanced plasma lines and HF enhanced ion lines in the recorded spectra of the ultra high frequency (UHF)/very high frequency (VHF) backscatter radars. These waves can grow to large amplitudes and become nonlinear waves. The nonlinear Schrodinger equation and Korteweg-de Vries equation governing the nonlinear evolution of Langmuir waves and ion acoustic waves are derived and solved. It is shown that the solutions of these equations can be either periodic or solitary depending on the physical conditions. The analyses show the conditions of generating Langmuir soliton and ion acoustic soliton.