Relaxation of the order parameter in the BCS model

Relaxation of the order parameter of a “pure” superconductor due to the electron-phonon interaction is considered in a homogeneous case. The process of relaxation has a simple physical interpretation as the variation of the number of electrons in Cooper pairs due to excitation collisions accompanied by the absorption and emission of phonons. It is shown that, in the neighborhood of the critical temperature, the relaxation time of the modulus of the order parameter is much greater than the time between excitation collisions.