Theory of the diffraction of electromagnetic waves by a plasma sphere with allowance for spatial dispersion

The present study determines the fields of low-frequency longitudinal ion-acoustic waves excited via the diffraction of a plane TM wave by a homogeneous plasma sphere. The possibility of the focusing of the longitudinal wave in a sphere of large radius is demonstrated. Amplitudes of secondary fields in the frequency range of ion-acoustic waves are calculated, and expressions are obtained for the frequencies at which the field amplitudes increase resonantly. The effect of the damping of the longitudinal waves on the diffraction properties of the plasma sphere is considered, and attention is given to both the normal and anomalous skin effects.