Kovalenko A. Investigation of damping of non-linear large amplitude Langmuir oscillations via computer simulation.

The thesis is dedicated to clarifying the mechanisms of damping of large amplitude Langmuir oscillations in a collisionless plasma. There are considered the peculiarities of electron oscillations in different geometrical systems such as a transversely bounded plasma consisting of positive and negative ions; a non-equilibrium plasma layer; boundless homogeneous and inhomogeneous plasmas. It is showed that the electrical field of Langmuir oscillations of a cold plasma contains a time-independent component leading to a movement of ions. In case of a plasma layer in the central part of it, they start to move to the centre of the layer, despite the fact that the layer, as a whole, has a positive charge. This results in intersection of electron trajectories after a while, i.e. a one-dimensional turbulence develops in the system. In a cold plasma electron trajectories cross at any amplitudes of initial perturbation. It is pointed out that there is a major difference between the turbulization of Langmuir oscil lations under study and the modulation instability in a warm plasma. The formula for time of intersection is obtained. To study a possible aperiodic heating of plasma electrons in the electrical field of strong Langmuir oscillations having energy exceeding the thermal plasma energy, it is proposed a new computational method. It permits to differentiate the physical and non-physical (numerical) growth of temperature.