Conservation of oscillator strength density for a spectral series in the one-particle potential approximation

It is shown in the quasiclassical approximation that the oscillator strength density f/sub n/dn/E of the spectral series of the hydrogen atom in the near-threshold region is conserved during the interaction of the atom with plasma microfields or in the modeling of the influence of the surrounding particles by the effective central potential. This property in the approximation of nonperturbation of the lower state generating the series is a consequence of the invariance of the quasiclassical density of the states of an electron in phase space. The oscillator strength density of the series is determined by the form of the potential in the region of localization of the lower state and is independent of its form outside this region. It is concluded that the conservation of oscillator strength density in the near-threshold region is a common property of the one-particle potential approximation, and its violation, observed experimentally, cannot be described in the framework of this approximation