It is a goal of our proposals to investigate the collisionless processes for energy and momentum exchange in plasma via excitation and absorption of plasma waves. Two different types of waves are to be considered: Alfven waves that organize the momentum transfer between counterstreaming ion populations via pitch angle scattering of resonant particles and lower hybrid waves that are very effective in energy transfer from ion sources of free energy to plasma electrons. For Alfven waves we are planning the solution of two following problems: the excitation of strongly nonlinear Alfven waves in a form of shocklets by counterstreaming ions, appearing in the solar wind in the upstream region of planetary and cometary bow-shocks, and the cosmic ray transport by galactic wind due to coupling between these two plasmas caused by Alfven waves. For lower hybrid waves, excited by ion beams in a plasma, the nonlinear theory is to be contructed describing the saturation of the lower hybrid instability by nonlinear wave cascading and wave absorption by plasma electrons and ions. The most important cascade mechanism that is to be under detailed analysis, is the modulational instability and collaspe of lower hybrid waves. Finally, as the possible example of collective interactions in collisional dominated plasma, the formation of the weak electrostatic shock inside the cometary ionosphere would be considered.
