A Short History of Pulse Tube Refrigerators
Pulse Tube Coolers are a recent innovation. They were first reported by Prof. W. Gifford and his graduate student, R. Longsworth, of Syracuse University (Winter Annual Meeting of ASME, 1963). Prof. Gifford had noticed that blanked off plumbing lines connected to gas compressors got hot at the closed end. Connecting such a line to a compressor through a regenerator produced cooling at one end and heating at the other. This was the Basic Pulse Tube. In the first report, 150 kelvins was achieved in a one stage cooler and 120 kelvins in a two stage device. A few years later the coolers had reached 120 kelvins and 85 kelvins respectively. This performance was not encouraging. The coolers were too inefficient. By the end of the 1960's Pulse Tubes had become an intellectual curiosity and were abandoned as a useful cooler.
Basic Pulse Tube Refrigerator
In the late 1970's, Dr. J. Wheatley at the DOE's Los Alamos National Laboratory became interested in a related technology: thermo-acoustic engines and coolers. These are a class of inherently irreversible machines that operate at acoustic resonance (Pulse Tubes operate at frequencies well below resonance). These devices are even less efficient. The coolers were driven by a simple loudspeaker; while the engines had no moving parts other than the working fluid.
In 1981, after hearing a talk by Dr. Wheatley (16th International Conference on Low Temperature Physics), Dr. P. Kittel of NASA's Ames Research Center recognized the potential for space applications of a cooler with a single moving part. The principal benefits are greater reliability and lower cost compared to the Stirling cooler and an order of magnitude lower mass, lower cost, and longer life than the current state of the art coolers: stored cryogens. Another benefit is that there are no cold moving parts which enhances life time and removes vibration causing components from the cold head. Additionally, Pulse Tubes use the same technologies as Stirling coolers. They could benefit from all the flexure-bearing, gas-gap seal compressor and regenerator developments that were just starting for space qualified Stirling coolers.
In 1982, Dr. Kittel in partnership with Dr. R. Radebaugh of NIST began developing Pulse Tubes. The first breakthrough came the next year. At the 1983 Cryogenic Engineering Conference, Dr. E. Mikulin (Moscow Bauman State Technical University, Russia, formerly the Moscow High Technical School, USSR) showed that the efficiency could be increased by inserting an orifice and reservoir at the hot end. This increased the phase shift between the pressure and mass flow oscillations. This observation led to the Orifice Pulse Tube which has become the standard implementation. Single stage Orifice Pulse Tubes have reached temperatures below 30 kelvin (various workers, late 1980's); while a 3-stage device built by Prof. Matsubara at Nihon University in Japan has reached 3.6 kelvin (15th International Cryogenic Engineering Conference, 1994).
Orifice Pulse Tube
By the late 1980's, a good theoretical understanding had been developed at NIST (NASA funded). This was 1-D thermodynamic model based on Enthalpy flow. During this time, technology transfer from the NIST/NASA team was well under way with a number of companies. The biggest industrial effort was at TRW. They started in 1987 with a development contract from NASA Ames and with substantial in-house funding. TRW built a number of Pulse Tubes, including the first one to operate below 10 kelvin. In 1994 TRW delivered its first Pulse Tube built under contract to the Air Force's Phillips Laboratory. The success of this cooler (1 watt at 35 kelvins with 200 watts of input power) lead to TRW being selected to build a Pulse Tube for the AIRS instrument for the EOS program. This is a 1.5 watts at 55 kelvins cooler with an input power of less than 100 watts; an efficiency comparable to Stirling coolers.
Meanwhile; Dr. G. Swift at Los Alamos with DoE funds had continued developing the thermo-acoustic compressor. The compressor was coupled to a Pulse Tube developed by Dr. R. Radebaugh at NIST. This produced a cooler with no moving parts (4th Interagency Meeting on Cryocoolers, 1990). The cooler reached 90 kelvin and produced 5 watts of cooling at 120 kelvins with an input thermal power of 3 kilowatts. Not very efficient, but tremendous potential for reliability!
By the late 1980's many laboratories around the world had started Pulse Tube development. The principal groups are located in China, Japan, France and Germany. Many different configurations have been investigated. One of the most active is the group lead by Prof. Matsubara (Nihon University, Japan). They were the first to develop the moving plug or hot piston Pulse Tube. This added a second moving component and increases the efficiency. The most important development has been the innovation of the double inlet Pulse Tube by Dr. Zhu et. al. of Xi'an Jiaotong University, China (13th International Cryogenic Engineering Conference, 1990). This technique was further refined into the multiple by-pass Pulse Tube by Dr. Zhou of the Academia Sinica, China (7th International Cryocooler Conference, 1992). In 1994, the first commercially available Pulse Tube was announced in Japan by Iwatani as a replacement for the cold head of a Gifford-McMahon cooler. (Gifford-McMahon coolers are a low cost variation of a Stirling cooler. They are the most common type of cryogenic refrigerator sold industrially.)
Multiple By-pass Pulse Tube
The quality of the analytic models have also improved over the years. NASA Ames has been developing a 2-D model that incorporates both thermodynamics and hydrodynamics. This model has shown that there are secondary flows in the system that earlier 1-D models had ignored. The existence of these secondary flows has been confirmed by flow measurements made at NASA Ames (8th International Cryocooler Conference, 1994). Current work at Ames also includes the fabrication of a 4-stage Pulse Tube based on the multiple by-pass approach.
A number of American manufactures are also interested in replacing Gifford-McMahon coolers with Pulse Tubes; although, none of the major industrial manufactures are close to making this change. When they make this change, the new coolers will be lower cost, lower vibration, and more reliable. Most of the non-aerospace work on Pulse Tubes has been in small companies working with SBIR contracts (click here for information on NASA's SBIR program).
For more information see the Pulse Tube Refrigeration page from the Cryogenics Group of the Sensors and Instrumentation Branch at ARC. There is also some pulse tube information on the JPL Cryocooler Development and Test Program page.
Converted to HTML and hyperlinks added on October 7, 1994. Picture of Pulse Tube added October 18, 1994. New top logo and hyperlink to Pulse Tube Refrigeration page added January 26, 1995. Link to JPL Pulse Tube information added April 20, 1995. A few outdated links updated and the link to TRW added July 3, 1995. Link to the Moscow Bauman State Technical University, which before 1989 was the Moscow High Technical School, added January 19, 1996, based on comments from Andrei Fedorov. A few links updated on March 4, 1997. Please see my Disclaimer and Web Policy page. Maintained by Gordon Johnston.
Gordon.Johnston@hq.nasa.govThe world wide web uniform resource locator (URL) for this page is:
http://ranier.hq.nasa.gov/Sensors_page/Cryo/CryoPT/CryoPTHist.html