Gregory Kaduchak Philip L. Marston
Dept. of Phys., Washington State Univ., Pullman, WA 99164-2814
A prominent feature predicted for the backscattering of tone bursts by
thin spherical shells is an enhancement of a guided wave contribution near the
first longitudinal resonance. This has been explained with a backward ray model
of a leaky Lamb wave where energy is leaked off without having circumnavigated
the back side of the shell [P. L. Marston et al., J. Acoust. Soc. Am. 90, 2341
(1991); D. H. Hughes, Ph.D. thesis, Washington State University (1992)]. The
relevant s[sub 2b] Lamb wave has opposing group and phase velocities giving
rise to prompt radiation following the direct specular echo. The present
research gives a comparison between a ray theory approximation and experiments
in which tone bursts having carrier frequencies in the range 595