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High-Temperature Oscillator and Digital Clock--Linear Measurements, Inc., 4174 Sorento Valley Boulevard, San Diego, CA 92121-1483; 619-535-2172
Mr. Harper J. Whitehouse, Principal Investigator
Mr. Robert Hatch, Business Official
DOE Grant No. DE-FG03-99ER82812
Amount: $747,235
The Department of Energy and the renewable energy industry need electronic devices and sensors to control and optimize the drilling of geothermal wells. This project will develop a high-temperature oscillator and digital clock to provide the precision timing required to control other components and subsystems in such high temperature systems as measurement-while-drilling (MWD), logging-while-drilling (LWD), and data telemetry. The high-temperature oscillator and digital clock will utilize a surface acoustic wave (SAW) device in which a pair of metal transducers operates on a piezoelectric crystal substrate. An electronic amplifier connected to one transducer generates an acoustic surface wave that propagates along the surface to the second transducer where the acoustic wave is converted into an electrical signal and fed back to first transducer. The analog electrical signal from the surface acoustic wave oscillator will be electronically converted to a digital clock signal. In Phase I, the new quartz-like material langasite (LGS, La3Ga5SiO14) was shown to have a SAW crystal cut with a zero temperature coefficient of frequency at 160oC. For the high-temperature electronics, specially fabricated gallium arsenide (GaAs) transistors were shown to operate at 400oC. High-temperature circuit board materials were identified along with the other necessary passive electronic components needed. In Phase II all of the acoustic and electronic components will be combined in an experimental prototype high-temperature oscillator and digital clock. Special surface mount circuit board technology will be used to minimize thermally-induced stresses. The prototype circuit will be tested at temperatures from near 0oC to temperatures greater than 300oC, and the components will be optimized to maintain a frequency stability of +/-500 parts per million (ppm) accuracy over a temperature range from 20oC to greater than 300oC.
Commercial Applications and Other Benefits as described by the awardee: In addition to geothermal well drilling and logging, the high-temperature digital clock should be useful wherever temperature and pressure measurements are needed in high-temperature, adverse environments. Applications include aircraft piston, jet engine, and automobile engine control, as well as nuclear power plant safety.