Dynamics of strong Langmuir turbulence - computer simulations

One-dimensional computer simulation of the free-evolving turbulence of Langmuir waves with an initial Gaussian spectral distribution and random phases of Fourier harmonics is reported. The discrete Fourier transformation is applied to the Zakharov set of equations and the resulting equations for up to 512 Fourier harmonics of electric field and ion density perturbations are solved by the Runge-Kutta method. The time dependences of energy densities of plasmons and ion sound waves, spatial profiles of plasmon energy and ion density as well as electric field and density spectra are calculated in each step, as illustrated by many diagrams in the paper. In all the runs performed, the modulation processes are dominant. About 60% of plasmons become trapped in density wells with ion acoustic waves being simultaneously excited. Nonlinear formations such as quasisolitons and cavitons are well seen in a number of plots of temporal evolution of the density and plasmon energy perturbations. (J.U.)