Low-Cost, Thin-Film Multijunction Thermal Converter Wins 1994 R&D; 100 Award

A multilayer, thin-film multijunction thermal converter, or MJTC, developed jointly by the National Institute of Standards and Technology and Ballantine Laboratories Inc. of Cedar Knolls, N.J., has been named one of the "100 most technologically significant new products of the year" by Research and Development magazine.

The result of a cooperative research and development agreement between the two organizations, this approach to the fabrication of thermal converters permits mass production of a previously difficult-to-make, hand-made device, with a subsequent reduction in price.

The developers, Joseph Kinard and Donald Novotny of NIST's Electronics and Electrical Engineering Laboratory, along with De-Xiang Huang of Ballantine Laboratories, will be honored at the 32nd annual R&D; 100 Awards Banquet on Thursday, Sept. 22 at Chicago's Museum of Science and Industry.

Thermal converters, which are the most accurate calibration standards for ac voltage and current, also produce the most precise measurement method for both. According to the developers, conventional thermal converters contain a heater resistor, usually wire, and a temperature sensor, usually a wire thermocouple. Wire MJTCs, containing many thermocouples, are used as primary and working standards in the national calibration laboratories of all the major industrialized nations.

The new multilayer, thin-film MJTCs were developed to provide more accurate primary standards of ac-dc difference than were previously obtainable and to permit more accurate instrumentation for ac voltage and current measurements.

"The novel fabrication technology and thin-film, low-stress construction of these MJTCs permit operation at cryogenic temperatures where thermoelectric errors are lower," says Kinard.

By bringing high-performance thermal transfer instrumentation to the general measurement and calibration community, the new converters may enable widespread reduction of uncertainty in ac voltage calibration. They may also allow high-accuracy voltage and current measurements from below audio frequency to 100 megahertz. The new thin-film MJTC technology may have further applications in vacuum, flow and other measurement areas.

Research and Development magazine annually honors inventors and scientists around the world by selecting the 100 most technologically significant new products of the past year. Recipients are selected on the basis of their invention's importance, uniqueness and usefulness from a technical standpoint by the magazine's editors and a panel of technical experts. Since 1973, NIST researchers have won a total of 76 R&D; 100 awards.

An agency of the Commerce Department's Technology Administration, NIST promotes economic growth by working with industry to develop and apply technology, measurements and standards.