### ASA 124th Meeting New Orleans 1992 October

## 3pUW3. Use of vector Bragg wave-number scattering condition in bistatic
scattering experiments.

**John Oeschger
**

**
**
*Univ. of Rhode Island, Kingston, RI
*

*
*
**Louis Goodman
**

**
Diane Szargowicz
**

**
**
*Naval Undersea Warfare Ctr., Newport, RI
*

*
*
**Peter Hebda
**

**
**
*Americom Corp., Middletown, RI
*

*
*
Applying the Born approximation to a buoyant plume yields the Bragg
scattering condition that determines along with knowledge of the scattering
potential, the scattered wave at any given scattering angle. The Bragg
scattering condition allows for information obtained from the same Bragg
direction albeit different scattering angles to be pieced together to form an
entire Bragg wave-number spectrum of the scatterer. Data are taken in a
multiple bistatic configuration whose geometry is predetermined via knowledge
of the bandwidth of the transducers and the desired overlap of the resulting
Bragg phase space. Results are given for a buoyant axisymmetric laminar plume.
As an aside of the Bragg scattering condition an empirical formula derived from
the far-field expressions for the Green's function solution to the Hemholtz
equation given the scattering dimensionality of the plume, which is
acoustically measured and shown to give expected results.