Study On Plasmons Collapse And Turbulence Spectra In Laser-plasma

With the development of inertial confinement fusion (ICF) research and plasma physics, the study on interactions between laser and plasma has got a great improvement. The research on interactions has been one of the most active and fruitful points in plasma physics field, it is also a basic and important content in ICF.The laser propagation in plasma may induce varied instability in plasma and excite Langmuir wave, ion acoustic wave, et al. There are frequent interactions between waves and particles; and there are also large amounts of energy exchanges among waves, which would compose very complex interactions. These interactions would result in laser scattering, energetic electrons and ions generation, and plasma turbulence. Turbulence research, which is to discuss random interactions of numerous motions in different scales, is an important branch in physics.Based on the nonlinear complete Zakharov equations, which depicts strong turbulence near the critical surface in laser-plasma, the interactions of electromagnetic wave, langmuir wave and ion acoustic wave are analyzed. The modulation instability with finite amplitude is discussed, too. Using fast Fourier transform method, Zakharov equations are numerically solved in 2-dimantional with 3-field component and the turbulence field evolutions during the collapse process can be clearly described. The simulated results can be used to explain the laser plasmas filamentation, the langmuir wave's excitation and collapse, and the energy equilibration over both langmuir wave and transverse wave. With numerical result, the max values for langmuir wave intensity and destiny perturbation in non-static limit are calculated, they are in a good agreement with the laser-plasma experiments (such as filamentation effect, the formation of density cavity). Furthermore, the energy density spectrum for electromagnetic wave, Langmuir wave and ion acoustic wave are obtained and used to interpret spectra evolution with time. The turbulence spectra are very useful when discussing turbulent acceleration and anomalous collision in laser plasmas. These researches provide a clearer physical understanding for the strong turbulence in laser plasma by numerical simulation, and make the plasmon collapse process more comprehending.