Generalized kinetic equation for an electron-phonon system interacting with a strong electromagnetic field

A generalized kinetic equation for the electron-phonon interaction system under the effect of a strong electromagnetic wave field is deduced on the base of the method of elimination of the Bogolyubov boson operators. This equation permits to study kinetic and, particularly, wave properties of this system. Conditions, at which a collision integral permits to introduce a notion of relaxation time, are studied. Relaxation time is calculated as a function of frequency and external field intensity for the cases of electron-acoustic phonon interaction