Development of large-scale acoustic waveguides for liquid-level measurements

Large-scale magnetostrictive ultrasonic waveguides are being developed and tested for liquid-level measurement. The use of inexpensive, commercially available, nickel tubing provides a homogeneous waveguide with nondispersive transmission properties and good independence of torsional and extensional wave modes. Because the entire waveguide is magnetostrictive, acoustic excitation and sensing is possible at any point along the length of the waveguide. The problems of establishing and maintaining circumferential fields for torsional wave generation have been solved by electromagnetic field generation. Prototype devices have been built and tested which exhibit a linear relationship between either torsional amplitude or phase velocity and depth of immersion.