Inst. of Appl. Phys. of the Russian Acad. of Sci., 46 Uljanov St., 603600, Nizhny Novgorod, Russia
Woods Hole Oceanographic Inst., Woods Hole, MA 02543
The problems for creating low-frequency, high-efficiency sources for acoustic monitoring of climatic temperature changes in ocean basins are discussed. The properties of monopole, dipole, Helmholtz resonator, resonate 1/4 wavelength tube sources with wave parameter KA<1 are discussed where K is the acoustic wave number and A is the characteristic dimension of the source. Monopole resonant sources have the highest quality and can be realized with available deformation of existingmaterials in gas-filled interiors. It is shown how to overcome the main engineering problems for this source to provide (1) a uniform mode of oscillation of the radiation surfaces, (2) the highest bandwidth at maximum efficiency, and (3) the minimum strain in the radiating surfaces. The modeling data and the results of source tests show high efficiency over a bandwidth suitable for acoustic monitoring.