Thermophone projectors using nanostructure materials

Thermophone transducers fabricated from new nanoscale materials hold the promise of a new transducer technology for the Navy with no moving parts that operate over a broad frequency range and can be designed to be lighter and thinner than competing technologies. This potentially makes them ideal for use as high performance conformal projectors on autonomous underwater vehicles, submarines, and other small craft. Although thermophone devices have been understood for nearly a century, [Phys. Rev. 10, 22 (1917)], new nanostructure materials with extremely low heat capacities per surface area have recently become available which have the potential of greatly increasing their efficiency. Thermodynamic models show that certain surfaces, gasses, and enclosures will increase the acoustic efficiency. However each of these modifications of the base design has drawbacks as well. These will be discussed from a theoretical standpoint and results from laboratory testing will help to verify these hypotheses. [Work supported by NRL.]