Abstract: An improved transducer for generating and receiving acoustic energy. A transducer core is constructed by bonding together a plurality of concentric cylinders to provide a ferromagnetic core. A magnetic vector is established circumferentially about the core by passing a current through an electrical winding, wound torridially about the core. A pulsed current source connected across the core provides a high-magnitude, short-duration pulse output establishing current flow from one end to the other end of all of the concentric cylinders. Current flow within the magnetic field causes a force vector and magnetic vector creating a pressure wave.

Abstract: A rod of magnetostrictive material has its ends placed between steel bars which provide compression on the rod by tensioning wires connected between the bars. Preferably, the wires are equally spaced along the bars from the rod so that when the wires are equally tensioned the rod is under no bending stress. The tension of the wires (and from this value, the compression of the rod) is conveniently determined by the freqency of vibration of the wires using known physical relationships between these quantities.

Abstract: A magnetic drive is provided for a flextensional transducer in order to adapt the flextensional transducer for operation at increased ocean depths without the necessity of liquid filling and complex decoupling devices. In one embodiment an electro-magnetic actuator is positioned between the walls of the flextensional shell and is driven electrically so as to deflect the shell walls outwardly. The magnetic actuator in one embodiment includes a permanent magnet and pole pieces supported on one of the interior walls of the shell, with a moving coil positioned between the pole pieces and supported on a diametrically opposite wall of the shell. In an alternative embodiment, the magnetic actuation may be in the form of a rod of magnetostrictive material between opposing interior walls of the shell, which is actuated by an overwound electrical coil, with the shell being of magnetic material such as magnetic iron.

Abstract: An underwater sound generator composed of a ferrofluid contained within a toroidal container which has a rigid bottom and top and elastic cylindrical side walls. A coil of wire links the toroidal container and is adapted to be connected to a dc bias source to produce a biasing magnetic field, H.sub.BIAS, which drives the magnetization of the ferrofluid well into saturation. Two oppositely wound coils of wire respectively link the inner side wall and the outer side wall and are adapted to be connected in series to an ac signal source to produce a time-varying magnetic field, H.sub.AC, which modulates H.sub.BIAS. The wires are equally spaced in the volume occupied by the ferrofluid. The gradient of H.sub.AC in the radial direction provides the time-varying force on the ferrofluid. The resulting ferrofluid motion in the radial direction is transmitted through the outer elastic side wall to supply acoustic motion to the surrounding water.

Abstract: A magnetic fluid transducer for producing a low-frequency sound field in a fluid medium. The device comprises a non-magnetic cylindrical housing with end windows. The housing is surrounded by a magnetic-field-generator means and contains a magnetic fluid within the housing. The magnetic field penetrates the housing and interacts with the magnetic fluid. A body force is developed within the fluid which produces an internal pressure in local regions defined by the lines of magnetic flux. This internal pressure is transmitted by an acoustic transmitting medium to the surrounding fluid as a sound pressure level.

Abstract: Disclosed is an electromagnetic acoustic transducer, including a source of magnetic flux for establishing a static magnetic field, an electrical conductor for conducting an alternating current in the static magnetic field, and an electrically conductive, nonmagnetic shield disposed between the source of magnetic flux and the conductor.

Abstract: A free-flooding, deep submergence cylindrical magnetostrictive transducer ving a plurality of identical, coaxial, ring-shaped scrolls, surrounded by a toroidal coil, the scrolls being vibration isolated from each other and from the coil, and having ring resonance frequency sufficiently close to cavity resonance frequency for broadband operation, i.e. approximately one octave at the 6 db down points.