Abstract: An eddy-current sensor having a thimble shaped alumina housing into which is positioned first and second coils wound about an insulating coil support. A Kovar sealing ring seals the alumina housing to a metallic base member to which is secured a protective tube carrying an electrical cable which makes electrical connection with the coils. A multifaceted nut secured to the metallic shielding of the cable nestles within a complementary shaped insulating member to prevent the cable from being twisted or withdrawn from the sensor thus maintaining electrical integrity.

Abstract: A method of impregnating a flexible, porous cellulosic sheet material involves passing the sheet through a low viscosity resin and across the resonant vibrating surface and through a cavitated zone in close proximity to at least one completely immersed ultrasonic wave generator, operating at a frequency and radiated power level effective to provide a combination vibratory pressure on the resin and cavitation effect causing degassing and heating of the resin, followed by passing the impregnated sheet through a drying means.

Abstract: A method of calibrating acoustic emission transducers. The sensitivity of a standard transducer is first determined utilizing a reciprocity calibration technique, and the standard transducer and the acoustic emission transducer are then connected to a bounded acoustic medium. Random acoustic white noise is transmitted into the acoustic medium thereby establishing a multi-mode reverberant sound field, and the output responses from the standard transducer and the acoustic emission transducer to the reverberant sound field are obtained and compared to determine the sensitivity of the acoustic emission transducer.

Abstract: A neutron flux radiation detector is provided that utilizes neutron radiation induced nonlinear acoustic behavior in water, with the resultant mixing of two ultrasonic signals in transit through the liquid, to provide a measure of ambient radiation levels. Nonlinear elastic properties are imparted to the water by the presence of microcavities which are formed when high-energy neutrons collide with the waters atomic nuclei.The detector employs an ultrasonic transmitting transducer which is driven simultaneously at two different frequencies. The acoustic output is transmitted through a container housing a pool of distilled water. Only when radiation is present will the acoustic signals in transit through the water undergo harmonic distortion and "mix", thereby generating sum and difference frequencies. These sum and difference frequencies are then sensed using a separate receiving transducer, and are identified as a measure of the ambient radiation level.

Abstract: An easily replaceable acoustic transducer assembly is provided for usage in high temperature applications. The improved structure permits efficient acoustical coupling between the component parts of the tranducer assembly, and is more readily reproducible in sensitivity and frequency response. A generally tubular high temperature resistant metal enclosure is provided with an acoustical window which is coupled to the piezoelectric transducer element. The piezoelectric element is acoustically coupled to a damping block member. Acoustical coupling between the active elements of the transducer assembly is had from a compressive means integral within the enclosure member.

Abstract: An electroacoustic ultrasonic transducer is described which is usable under high pressure and high temperature operating conditions, and is readily replaceable. A piezoelectric transducer element is disposed within a metallic housing and coupled to a metallic acoustic window which is exposed to the sensed acoustic medium, with very efficient acoustic coupling between the piezoelectric element, the acoustic window, and a damping block disposed behind the piezoelectric element.