3K cold head regenerator design
The regenerator design with specific particle compositions and multi-layer screens addresses the need for improved cooling capacity at 3 K, doubling cooling performance and achieving optimized temperatures below 2.3 K in cryogenic refrigerators.
Patent Information
- Application Number
- JP2025543127
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-07-13
- Filing Date
- 2023-07-13
- Publication Date
- 2026-01-29
AI Technical Summary
Existing cryogenic refrigerators are not optimized for temperatures below 4.2 K, particularly for applications requiring higher cooling capacities at 3 K, limiting their performance and efficiency in quantum computing and dilution refrigerator markets.
A regenerator design comprising four sections of different particles (tin-antimony, holmium copper, gadolinium oxysulfide, and gadolinium aluminate) separated by multi-layer screens, optimized for cooling performance at 2.3 K and 3 K, using materials like copper, phosphor bronze, and brass meshes to enhance cooling capacity and efficiency.
The design achieves doubled cooling capacity at 3 K compared to conventional designs, providing at least 1 Watt of cooling capacity and optimized cooling performance at temperatures below 2.3 K, enhancing efficiency and reliability for cryogenic refrigerators.
Smart Images
Figure 2026503647000001_ABST
Abstract
Description
[Technical Field]
[0001] The present invention relates to cryogenic refrigerators, and more particularly to a cold head regenerator design that can achieve optimized cooling performance at temperatures below 2.3K and 3 Kelvin. [Background technology]
[0002] The quantum computing and dilution refrigerator (DR) markets are growing very rapidly, and the development of high-cooling-capacity, ultra-low-vibration, fast-cooling, energy-efficient, and reliable cryogenic refrigerators for these markets is crucial. Typically, for most dilution refrigerators, higher cooling capacities are required below 3 K rather than 4.2 K. Commercially available 4 K cryogenic refrigerators (either pulse tube or GM) are typically designed for optimal performance at 4.2 K. Because the performance of equipment used in applications such as these can be highly dependent on temperature and the amount of cooling, there is a need for cryogenic refrigerators that can provide temperatures below 2.3 K while improving cooling capacity and performance at 3 K. Summary of the Invention
[0003] The present invention includes a regenerator design for a cryogenic refrigerator capable of achieving optimized cooling performance at temperatures of at least 2.3 K and at 3 K. This design involves the use of four sections of different particles separated by a series of multi-layer screens. The four sections contain tin-antimony particles, holmium copper particles, gadolinium oxysulfide particles, and gadolinium aluminate particles. Each multi-layer screen is formed by adjacent layers of copper mesh, fibrous mesh, phosphor bronze mesh, another layer of fibrous mesh, and a final layer of brass mesh. The particle composition and multi-layer screens allow compressed helium to more efficiently cool the head of a cryogenic refrigerator equipped with a regenerator according to the present invention, thereby enabling the cryogenic refrigerator to achieve optimized cooling performance at temperatures below 2.3 K and at 3 K.
[0004] The present invention will be more fully understood and appreciated from the following detailed description taken in conjunction with the accompanying drawings. [Brief explanation of the drawings]
[0005] [Figure 1] 1 is a cross-sectional view of a tubular cold head regenerator chamber illustrating a regenerator chamber design in accordance with the present invention.
[0006] [Figure 2] 1 is a graph of the cooling capacity curve of the second stage of a two-stage cryogenic refrigerator equipped in accordance with the present invention.
[0007] [Figure 3] 1 is a graph of the cooling curve of a cryogenic refrigerator with a two-stage regenerator chamber according to the present invention operating at 60 Hz. DETAILED DESCRIPTION OF THE INVENTION
[0008] Detailed Description of the Invention Referring to the drawings, FIG. 1 shows a tubular regenerator chamber 10 for use in the cold head 24 of a cryogenic refrigerator 26 according to the present invention, with increased thermal capacity to achieve a temperature within the cold head of less than 2.3 K while optimizing heat lift at 3 K, with like numbers referring to like parts throughout. The regenerator chamber 10 comprises a first section 12 containing a first regenerator material, a second section 14 containing a second regenerator material, a third section 16 containing a third regenerator material, and a fourth section 18 containing a fourth regenerator material. Each of the first and second sections 12 and 14, the second and third sections 14 and 16, and the third and fourth sections 16 and 18 are separated by a multi-layer screen 20 interposed therebetween. The multi-layer screen 20 aids in rectifying the flow of the refrigeration fluid. The particular compositions of the first, second, third, and fourth regenerator materials, as well as the composition and arrangement of the multi-layer screen 20, allow the regenerator chamber 10, when used with compressed helium, to achieve temperatures below 2.3 K while increasing the cooling capacity at 3 K. As seen in Figure 1, the regenerator chamber 10 can be positioned within a tubular housing 22 for use as a two-stage regenerator in the coldhead 24 of a cryogenic refrigerator 26, which, when under load, provides at least 1 Watt of cooling capacity at 3 K.
[0009] Referring to FIG. 2, a two-stage cryocooler equipped in accordance with the present invention exhibited the cooling capacity shown in the graph. A cooling curve is seen in FIG. 3 when a constant heating power of 35 W was applied to the first stage while a constant heating power of 0.90 W was simultaneously applied to the second stage during cold head cooling from room temperature. When heat loads of 35 W and 0.90 W were simultaneously applied to the first and second stages, it took approximately 85 minutes for the first stage to reach 35 K and approximately 60 minutes for the second stage to reach 3.0 K. Since conventional designs provide 0.5 W of cooling capacity at 3 K under load, the present invention provides a doubling of the cooling capacity compared to existing designs, and thus the regenerator chamber 10 represents a significant improvement in the heat lift of a cryocooler equipped in accordance with the present invention.
[0010] The first regenerator material in the first section 12 may include tin-antimony (Sn—Sb) particles. The tin-antimony particles are preferably spherical, have a Sn:Sb composition of approximately 95:5, and a spherical diameter of 0.25 mm ± 0.03 mm. The second regenerator material in the second section 14 may include unoxidized holmium copper (HoCu) spherical particles with a diameter of approximately 0.15 to 0.445 mm. The third regenerator material in the third section 16 may include gadolinium oxysulfide (GdOS or GOS) particles, preferably spherical, with a diameter of approximately 0.15 to 0.35 mm. The fourth regenerator material in the fourth section 18 may include gadolinium aluminate (GdAlO or GAP) particles, preferably spherical, with a diameter of approximately 0.15 to 0.35 mm.
[0011] The multi-layer screen 20 includes a series of layers that provide flow optimization between the first section 12, the second section 14, the third section 16, and the fourth section 18. As an example, the multi-layer screen 20 may include five layers: a first layer 32, a second layer 34, a third layer 36, a fourth layer 38, and a fifth layer 40. At least one of the first layer 32, the second layer 34, the third layer 36, the fourth layer 38, and the fifth layer 40 includes a non-conductive (thermally) material having randomized flow paths extending vertically and horizontally therethrough such that the layer is permeable to the flow of a refrigeration fluid. In some embodiments, two or more of the first layer 32, the second layer 34, the third layer 36, the fourth layer 38, and the fifth layer 40 include a non-conductive (thermally) material. For example, first layer 32 may be one or more copper screens, second layer 34 may be a nonwoven fiber mesh pad, third layer 36 may be one or more phosphor bronze mesh screens, fourth layer 38 may be another mesh pad, and fifth layer 40 may be one or more brass screens.
[0012] As an example, the non-conductive material with randomized flow paths may include a non-woven fiber mesh pad, such as felt, which is felted, matted, or composed of fibers interlocked with a random orientation. As an example, wool felt having a thickness of approximately 1 / 8 to 1 / 16 inch, a wool felt grade of F1, and a density of 2.00 pounds per square yard is suitable. Alternatively, felt pads having a thickness ranging from 1 / 16 to 1 / 2 inch, a density ranging from 0.1 to 10 pounds per square yard, and a felt pad fill count ranging from 0 to 8 may be used. The non-conductive material may be formed from fibers other than wool, including other natural fibers such as cotton or linen, as well as man-made fibers such as those formed from polymers. The non-conductive material provides flow straightening of the cooling fluid, such as helium, by distributing the flow of the regenerating fluid vertically and horizontally across the regenerative chamber 10, thereby providing a more uniform flow through the regenerative chamber 10, i.e., horizontally and vertically within the regenerative chamber 10. As a result, other material pads with randomized channels extending vertically and horizontally therethrough can be used that provide the same vertical and horizontal flow commutation across the regenerator chamber 10 .
[0013] The remaining layers of the multi-layer screen 20 may be composed of metal screens made from metals such as aluminum, bronze, phosphor bronze, brass, and copper. For example, a 24-mesh copper screen made from copper wire with a diameter of 0.46 millimeters may be sufficient. Alternatively, the other layers of the first layer 32, second layer 34, third layer 36, fourth layer 38, and fifth layer 40 may be made from materials including copper, stainless steel, or brass with a mesh size ranging from 2 to 60 mesh. For example, a 200-mesh phosphor bronze screen made from phosphor bronze wire with a diameter of 0.0021 inches (0.05 mm) and an overall opening ratio of 33% may be used. Alternatively, a phosphor bronze screen between 80 and 400 mesh, or a 60-mesh brass screen made from brass wire with a diameter of 0.25 millimeters, may be used. Any of the first layer 32, second layer 34, third layer 36, fourth layer 38, and fifth layer 40 that are not formed from a non-conductive material may have any of these sizes and amounts of metal from 1 to 50 screens.
[0014] It should be recognized by those skilled in the art that additional rectifying layers may be used depending on the design of and materials used in the regenerator chamber 10. Additionally, the rectifying layers may use different rectifying materials or fewer combinations of rectifying materials in different locations, provided that the same degree of rectification is achieved and the regenerator chamber 10 can still provide at least 1 W of cooling capacity at 3 K for certain cryogenic refrigerators and significantly improved cooling capacity for other designs.
Claims
1. 1. A regenerator for a cryocooler, comprising: The first section consists of a quantity containing tin antimony particles; a second section consisting of holium copper particles; Third section: a quantity consisting of gadolinium oxysulfide particles; A fourth section: a quantity consisting of gadolinium aluminum particles; and A series of structures of multi-layer screens disposed between the first and second sections, between the second and third sections, and between the third and fourth sections, wherein each multi-layer screen includes at least one layer formed from a non-conductive material having a plurality of random flow channels.
2. In the regenerator according to claim 1, the non-conductive material comprises a non-woven fiber mesh pad.
3. In the regenerating device according to claim 2, the nonwoven fiber mesh pad is formed from a mass of felt.
4. In the regenerating device according to claim 3, the amount of felt is wool.
5. In the regenerating device of claim 3, the amount of felt is 1 / 16 inch to 1 / 2 inch thick.
6. 6. The recycling device according to claim 5, wherein the amount of felt in the nonwoven fiber mesh pad is F1 grade.
7. In the reclaiming device of claim 6, the amount of felt has a density of 0.1 to 10 pounds per square yard.
8. 8. The regenerating device of claim 7, wherein the amount of felt is a packing number between 0 and 8.
9. 3. The regenerator of claim 2, wherein the gadolinium aluminum particles have an average diameter of 0.15 to 0.35 millimeters.
10. 3. The regenerator of claim 2, wherein the amount of gadolinium aluminum particles has an average diameter in the range of 0.20 to 0.25 millimeters.
11. In the reproduction device as claimed in claim 2, each multi-layer screen series includes at least one layer of metal mesh.
12. 12. The regeneration device of claim 11, wherein the metal mesh is formed from a metal selected from aluminum, copper, stainless steel, phosphor bronze, or brass.
13. 10. A method for providing a cryocooler with a cold head that achieves temperatures below 2.3 K and has an optimized heat removal rate at 3 K, the method comprising the step of disposing the regenerator of claim 1 at the cold head of the cryocooler.