The development of a sonobuoy using sparker acoustic sources as an alternative to explosive SUS devices

This paper is on the development and testing of sparker acoustic sources deployed in a sonobuoy for environmental measurements. Currently, signal underwater sound (SUS) explosive acoustic source devices are used in the measurement of acoustic transmission loss and reverberation. Sparker acoustic sources are an alternative to explosives that offer potential as a cost-effective method of obtaining controllable, multiple, broadband acoustic pulses at various depths. Aircraft deployment constrains the design to a sonobuoy package, which limits the size of the electrical driver. Consequently, sparker efficiency of converting electrical into acoustic energy determines the source level. We report on development of high efficiency sparker acoustic sources, integration of the sparkers into a sonobuoy, and on sea tests characterizing the acoustic source level and spectrum from the sparker based sonobuoy. Sparker operation in ocean water typically has a low efficiency of converting electrical energy into acoustic energy. In order to maximize the source level produced by the sonobuoy, we investigated how the acoustic efficiency changes with sparker parameters, including geometry, electrode gap and electrical driver design. Based on test results we selected the most promising candidates for sonobuoy deployment. This lead to the design and fabrication of a sonobuoy that operates at high efficiency and accommodates small sparker arrays. We plan to report results of sea tests to characterize the acoustic energy and spectrum produced by the sonobuoy for operation as a function of depth, number of sparkers and electrical driver energy.