US Government As Represented by the Secretary of the Army

Bruce T Benwell

Harold Boesch, Jr

Christian G Reiff

Vincent J Ellis

Youn M Lee

John Latess

Harold E Boesch

Dave DeTroye

An apparatus for generating an acoustic signal which has a dielectric substrate having opposed first and second sides. A pair of electrodes are mounted on the first surface of the substrate so that the electrodes are spaced apart from each other. A high voltage power source is electrically connected to the electrodes to produce a high voltage electric potential between the electrodes and this high voltage electric potential is less than a level sufficient to create a surface arc discharge along the first surface of the dielectric substrate. An electrical conductor strip is mounted to the second side of the substrate. A trigger signal circuit then applies a trigger voltage signal to either the electrical connector strip or one of the electrodes which varies the electric field between the electrodes in an amount sufficient to ionize air adjacent one of the electrodes and create a surface arc discharge along the first surface of the dielectric between the electrodes which generates the acoustic impulse as a byproduct of the discharge.

Apparatus for generating an acoustic signal

An apparatus and method are provided for high intensity acoustic test cells that employ the Helmholtz resonator principle, incorporating at least one moderately-sized volume or test cell that is tunable to a given infrasonic to low-sonic frequency and generates sound of high intensity with very pure sinusoidal waveforms in this test cell or volume, by varying the geometry of a port which is connected to the test volume and open to either atmosphere or a second or input volume and by introducing to the test volume or the input volume a driving acoustic signal at the given tuned frequency. The apparatus and method are used for testing or performing experiments on materials, structures, devices, products, biological entities or humans at high acoustic intensities and frequencies in the low-sonic to infrasonic ranges.

High intensity infrasonic tunable resonant acoustic test cell

An acoustic impulse source has been developed and used to simulate the high coustic output of detonation driven acoustic sources. While detonation driven acoustic sources are capable of producing large acoustic signals (&gt;160 dB) at 10s and 100s of meters from the source, their laboratory use is limited due to the combustion byproducts. The present invention is capable of reproducing the downrange detonative source acoustic signals (170 dB) at short range, on the order of 1 meter, without noxious or large thermal byproducts. The present invention relies on the plasma formation resulting from electrical arc discharge in air to generate thermal impulses and the resultant acoustic signals. Utilizing multiple plasma channels and timing control of the formation of said channels, the present invention achieves increased efficiency and the ability to tailor the acoustic output signal to match the desired detonation source characteristic output.

Multiple plasma channel high output variable electro-acoustic pulse

A radio frequency gasket assembly having a flexible hollow tube enveloped a conductive layer, and filled with an incompressible fluid. In one embodiment thereof, the undeformed gasket is filled with a sufficient volume of incompressible fluid such that when the gasket is compressed proper contact pressure is achieved between adjacent conductive surfaces of the enclosure. In another embodiment thereof, the undeformed gasket is filled completely with an incompressible fluid, such as ethylene glycol. When the gasket is compressed, a portion of the fluid is allowed to collect in a spring-loaded reservoir, preventing excessive pressure build-up and rupture. When the compressive force is removed, the collected fluid re-enters the gasket.

Liquid-pressurized radio frequency interference gasket

A radio frequency gasket assembly having a flexible hollow tube enveloped a conductive layer, and filled with a compressible fluid, or a combination of both compressible and incompressible fluids. In one embodiment thereof, the undeformed gasket is filled completely with a compressible fluid, such as air. When the gasket is compressed, a portion of the fluid is allowed to collect in a spring-loaded reservoir, maintaining at all times a substantially constant internal pressure. When the compressive force is removed, the collected fluid re-enters the gasket, which may then assume its original undeformed profile. In another embodiment thereof, the undeformed gasket is filled with a mixture of both compressible and incompressible fluids. When the gasket is compressed, a portion of the compressible fluid is evacuated or collected in a spring-loaded reservoir or the like, maintaining at all times a substantially constant internal pressure. When the compressive force is removed, an equal amount of compressible fluid is re-introduced into the gasket, which may then assume its original undeformed profile.

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Sumerduck, VA, United States of America

Bruce T Benwell