Review article. UFN, 1960, volume LXX, issue. 2 and 3, 86 pages . One of the characteristic features of plasma (ionized gas) is the appearance of nonlinear effects already in relatively small and easily achievable electric fields. There are two reasons for this :. First of all , The free path of electrons in the plasma is very large., Because of this, the electron can receive more energy from the field ,. The second , Transmission of energy from electrons to atoms , molecules and ions are difficult due to the low ratio of the electron mass to the mass of these heavy particles As a result, the plasma electrons in the electric field are heated, and the complex dielectric permeability of the plasma begins to depend on the field strength. In other words, polarization and conduction current are already disproportionate to zero E, as a result of which electrodynamic processes in the plasma and, in particular, the propagation of electromagnetic waves acquire a nonlinear character (the principle of superposition and t. is violated). d. ).