Refrigeration – Gas compression – heat regeneration and expansion – e.g.,...
Reexamination Certificate
1999-02-02
2001-09-11
Doerrler, William (Department: 3744)
Refrigeration
Gas compression, heat regeneration and expansion, e.g.,...
Reexamination Certificate
active
06286318
ABSTRACT:
BACKGROUND OF THE INVENTION
Pulse tube refrigerating systems for producing cryogenic temperatures are known. For example, as described in Ishizaki et al., U.S. Pat. No. 5,269,147, incorporated by reference herein, a working fluid contained within a tube is compressed adiabatically by the introduction of pressurized fluid into the tube causing an increase in the temperature of the working fluid. Working fluid which has been compressed passes to a heat exchanger to transfer heat into the atmosphere. The pressurized fluid is then allowed to flow from the tube and working fluid returns to the tube and expands to decrease in temperature. The cooled working fluid passes to a refrigerating section where it is available as a coolant. The compression and expansion cycle is repeated.
SUMMARY OF THE INVENTION
A combination refrigerator and current lead assembly uses the pulse tube refrigeration system to provide cooling to a superconductor containing system as well as electrical connection between the superconductor system and a non-superconducting electrical power element. The assembly includes a pulse tube having a cold end and a warm end. A first electrical connector is attached to the warm end. A second electrical connector attached to the pulse tube supplies current to a lead.
Embodiments of this aspect of the invention may include one or more of the following features.
The lead is a high temperature superconductor lead. The second electrical connector is located at the cold end of the pulse tube. The pulse tube is formed of electrically conducting material.
According to another aspect of the invention, a combination refrigerator and current lead assembly includes two pulse tubes. Each pulse tube has a cold end and a warm end. An electrical connector is attached to the warm end of each pulse tube. A second electrical connector is attached to each pulse tube for supplying current to a lead.
Embodiments of this aspect of the invention may include one or more of the following features.
The leads are high temperature superconductor leads. The second electrical connectors are located at the cold ends of the pulse tubes. The pulse tubes are formed of electrically conducting material. An electrical isolator electrically isolates the pulse tubes from each other. A compressor delivers compressed gas to the pulse tubes. Regenerators are located in the flow path between the compressor and the pulse tubes. A valve controls the flow of gas between the compressor and the regenerators. Electrical isolators electrically isolate the pulse tubes from the regenerators, compressor and valve.
In an illustrated embodiment of the invention, a variable sized orifice is in fluid communication with the warm end of each pulse tube. A reservoir volume is in fluid communication with the orifice.
According to another aspect of the invention, a superconductor magnet assembly includes a combination refrigerator and current lead assembly and a superconductor magnet. A first high temperature superconductor lead and a second high temperature superconductor lead of the current lead assembly supply current to the superconductor magnet.
According to another aspect of the invention, a method of providing both cooling and current to leads includes providing two pulse tubes. The pulse tubes are formed from an electrically conductive material and a first electrical connector is located at a warm end of each pulse tube, and a second electrical connector is attached to each pulse tube. The first electrical connectors are used to attach each pulse tube to a power source. The second electrical connectors are used to attach each pulse tube to a respective lead, for example, a high temperature superconductor lead.
Advantages of the invention include an efficient method of providing current to a high temperature superconductor lead while simultaneously cooling the high temperature superconductor lead.
REFERENCES:
patent: 4895831 (1990-01-01), Laskaris
patent: 5269147 (1993-12-01), Ishizaki et al.
patent: 5412952 (1995-05-01), Ohtani et al.
patent: 5495718 (1996-03-01), Pierce et al.
patent: 5647218 (1997-07-01), Kuriyama et al.
patent: 5680768 (1997-10-01), Ratray et al.
patent: 5735127 (1998-04-01), Pfotenhauer et al.
patent: 5744959 (1998-04-01), Jeker et al.
patent: 197 04 485 A1 (1998-08-01), None
David, et al. “How to Achieve the Efficiency of a Gifford-Mac Mahon Cryocooler with a Pulse Tube Refrigerator”,Cryogenics, 30:262-266 (1990).
Maguire James F.
Sidi-Yekhlef Ahmed
Winn Peter M.
American Superconductor Corporation
Doerrler William
Drake Malik N.
Fish & Richardson P.C.
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