Excitation of Surface and Leaky Waves on a Solid Body – Gas Interface

We analyze excitation of bulk, leaky, and surface waves by a point time-harmonic forcing applied perpendicularly to a solid body – gas interface. The case where the sound speed in the gas is less than the Rayleigh-wave velocity on the solid surface is considered. Expressions for the radiation powers of longitudinal and transverse spherical waves in the solid body and of a Stoneley surface wave, averaged over their periods, are derived. Excitation of a spherical acoustic wave in the gas and a pseudo-Rayleigh leaky wave is analyzed. For the spatial region corresponding to zenith angles exceeding the arcsine of the ratio of the sound speed in the gas and the transverse-wave velocity in the solid body, where the leaky-wave energy is transformed into the acoustic wave, we derive formulas describing their summed radiated power.