The evolution of plasma electrons distribution function at soliton gas relaxation

The generalized soliton gas theory is used for investigating a strongly turbulent nonisothermal plasma. The excitation of a wide spectrum of Langmuir solitons is assumed, with the distribution function corresponding to the spectral energy density of turbulent noises found in recent numerical simulation experiments. Collisionless relaxation of dense soliton gas due to soliton-particle resonant interaction is discussed and the soliton kinetic equation derived. For the electron distribution function a quasilinear diffusion equation with time-dependent diffusion coefficient is obtained and its numerical integration performed. It is shown that the Landau damping of solitons leads to rapid formation of a plateau on electron distribution. Thus, the Landau damping of solitons ceases before their collisional relaxation starts to act. (J.U.)