| Volume 4, | Number 1 | March/April 1996 |
In commercial and aerospace markets, there is an established need for a reliable cooling system for specialized devices requiring very low temperatures. Under the Aerospace Industry Technology Program (AITP), a consortium of federal and industry partners is developing two prototype cryocooler systems, one compatible with low-cost commercial applications and one compatible with space usage. Under the AITP, the coolers will be integrated and tested with high-temperature superconducting filters.
The consortium is led by the Research and Development Division of Lockheed Missiles & Space Company, Inc. (LMSC), of Palo Alto, California, in partnership with Superconductivity Technology, Inc. (STI), a small business in Santa Barbara, California, the National Institute of Standards and Technology (NIST) in Colorado, and NASA's Goddard Space Flight Center in Maryland.
The successful development of cryocooler technology could significantly impact commercial markets, such as interference-free cellular phones, infrared sensors for safety surveillance and non-destructive testing, high-speed digital communication, weapon system switched filter banks, high-speed computing systems, and commercial electrical power conditioning. It is anticipated that the cooler technology developed under this program will improve systems reliability, extend the operating life to a least 40,000 hours, and reduce the production costs to $500 to $1000, which will create new cryocooler markets.
In the space arena, the technology has extensive and far-ranging applications, including spaceborne instrumentation systems, superior microwave filters for space communications, improved astronomy instruments and low-cost cryocoolers for space sensing and high-speed computing.
The effort will focus on the cooling system. Specifically, a pulse tube will be powered by one of two compressor options and integrated with a high-temperature superconducting filter (see figure).
The pulse tube cooler provides the required filter cooling. One critical component affecting cooling and power efficiency is the heat exchanger (regenerator). Present pulse tubes use a screen material, but a new type of regenerator (etched film) has led to a breakthrough in efficiency. The pulse tube eliminates the need for moving parts in the cold portion of the cooler and precision machining, resulting in higher reliability and lower production costs. The NASA-developed technology will be incorporated in the new design for both the commercial and space prototypes.
The design approach for the compressor, which incorporates moving parts, will differ for commercial and space applications. However, both approaches will seek to eliminate the wearing of seals. STI will develop a gas bearing system, while Lockheed will use flexures to maintain alignment during piston motion (based on the Oxford University approach). Both designs will stress reduced manufacturing costs.
The resulting prototype will then be integrated and tested with the high-temperature superconducting filters. STI is developing these filters for microminiature, ultrahigh-performance interference FR filters, which are targeted for wireless communications markets, such as cellular and personal communications systems. These filters are needed to prevent interference from nearby users. STI's high-temperature superconductor resonators are 100,000 times smaller than conventional filters. If successful, STI is expected to become the world leader in this technology. There are more than 40 million cellular subscribers worldwide today, and the market is expected to grow by 20 percent yearly well into the next century.
The AITP project allows industry to identify and recommend development programs and choose to partner with a NASA center if desired. This approach focuses on profitable industrial needs while simultaneously validating a NASA center's technology excellence.
The configuration shows the pulse tube providing the required filter cooling, powered by one of two compressor options.
For more information contact Carl Ray at NASA Headquarters. Phone: 202/358-4652 E-Mail: cray@hq.nasa.gov Or contact Neville Marzwell at the Jet Propulsion Laboratory. Phone: 818/354-6543 E-Mail: Neville.Marzwell@jpl.nasa.gov Please mention that you read about it in Innovation.
