Pulse tube cryocooler

Inactive Publication Date: 2008-10-23
SUMITOMO HEAVY IND LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0013]Accordingly, embodiments of the present invention may provide a novel and useful pulse tube cryocooler solving one or more of the problems discussed above.
[0014]More specifically, the embodiments of the present invention may provide a pulse tube cryocooler whereby it is possible to prevent generation of convection loss due to convection of atmosphere gas even if it is operated under a non-vacuum atmosphere.

Problems solved by technology

Because of this, thermal loss (convection loss) is generated between the first stage and the second stage so that serious loss for cooling capacity may be generated in the pulse tube cryocooler.
Accordingly, in this case, it is difficult to prevent the convection loss so that cooling a subject to be cooled of the pulse tube cryocooler is not influenced by the convection loss.

Method used

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  • Pulse tube cryocooler
  • Pulse tube cryocooler
  • Pulse tube cryocooler

Examples

Experimental program
Comparison scheme
Effect test

first embodiment

[0056]FIG. 3 shows the example where the pulse tube cryocooler 1A of the present invention is applied to an MRI cryostat.

[0057]The pulse tube cryocooler 1A is provided in a neck tube 61 provided in a cryostat housing 60 of the MRI cryostat. The neck tube 61 has an upper part 61A having a large diameter and a lower part 61B having a small diameter. A neck tube heat station 68 is provided between the upper part 61A and the lower part 61B. The neck tube heat station 68 is thermally connected to a radiation shield 64 of the cryostat housing 60.

[0058]A vessel 65 configure to receive an MRI magnet 67 is provided at a most-bottom part of the neck tube 61. Liquid helium configured to cool the MRI magnet 67 fills the vessel 65. Because of this, a portion above the liquid helium 66 of the neck tube 61 is filled with the helium gas 62 so that the pulse tube cryocooler 1A is used under the helium atmosphere.

[0059]When the pulse tube cryocooler 1A is provided on the neck tube 61, the first stage...

second embodiment

[0096]FIG. 5 is a schematic view of a pulse tube cryocooler 1B of the present invention. In FIG. 5, parts that are the same as the parts shown in FIG. 2 and FIG. 3 are given the same reference numerals, and explanation thereof is omitted.

[0097]In the pulse tube cryocooler 1B of this example, a rectifier 70 is provided at the high temperature end part of the small diameter part 45 and a rectifier 71 is provided at the low temperature end part of the small diameter part 45. As discussed above, turbulent flow is generated in the small diameter part 45. While this turbulent flow is effective for improvement of the coefficient of heat transfer, this turbulent flow is not preferable from the perspective of maintaining the smooth flow of the operations gas in the second stage pulse tube 40A.

[0098]Because of this, in this example, the rectifiers 70 and 71 are provided so as to sandwich the small diameter part 45. As a result of this, the coefficient of heat transfer in the stage correspondi...

third embodiment

[0099]FIG. 6 is a schematic view of a pulse tube cryocooler 1C of the present invention. In FIG. 6 through FIG. 16, parts that are the same as the parts shown in FIG. 2 and FIG. 5 are given the same reference numerals, and explanation thereof is omitted.

[0100]The pulse tube cryocooler 1C of the third embodiment of the present invention includes a single hole plug 80 as a heat exchanging part for improving cooling efficiency of the stage corresponding position of the second stage pulse tube 40B.

[0101]This single hole plug 80 is inserted and fit into the inside of the stage corresponding position of the second stage pulse tube 40B. In addition, a single flow hole 81 where the operations gas flows is formed inside the single hole plug 80. This operations gas generates turbulent flow when the operations gas passed through the flow hole 81. Therefore, in the third embodiment as well as the first embodiment, the second stage pulse tube 40B can be cooled at the single hole plug 80 so that ...

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Abstract

A pulse tube cryocooler used under a non-vacuum atmosphere, the pulse tube cryocooler includes a pressure wave generator configured to generate pressure wave in an operations gas; a first stage regenerator having a high temperature end connected to the pressure wave generator; a second stage regenerator having a high temperature end connected to the first stage regenerator; a first stage pulse tube having a high temperature end and a low temperature end, the high temperature end being connected to a first buffer tank, the low temperature end being connected to a low temperature end of the first stage regenerator; a second stage pulse tube having a high temperature end and a low temperature end, the high temperature end being connected to a second buffer tank, the low temperature end being connected to a low temperature end of the second stage regenerator; a first stage cooling stage provided in a position where the first stage regenerator and the first stage pulse tube are connected; and a second stage cooling stage provided in a position where the second stage regenerator and the second stage pulse tube are connected.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention generally relates to pulse tube cryocoolers, and more specifically, to a pulse tube cryocooler used under non-vacuum atmosphere such as a helium atmosphere.[0003]2. Description of the Related Art[0004]Recently, as techniques of a pulse tube and design of an MRI (magnetic resonance imaging) cryostat has been improved, it has become possible to regenerate helium gas by using a pulse tube cryocooler. Furthermore, there are a single-stage type and a multi-stage type in the pulse tube cryocoolers. For example, in a two-stage pulse tube cryocooler, a first stage is cooled at approximately 40 K and a second stage is cooled at approximately 4 K. In addition, since the pulse tube cryocooler has little vibration and causes less noise in an MRI signal, the pulse tube cryocooler is more preferable than a GM (Gifford-McMahon) cryocooler having mechanical vibration.[0005]In the meantime, it is normal practice th...

Claims

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Application Information

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IPC IPC(8): F25B7/00F25B9/14
CPCF25B9/10F25B9/145F25B2309/1408F25B2309/1412F25B2309/1413F25B2309/1418F25B2309/1421F25B2309/14241F25B2400/17F25D19/006
InventorXU, MINGYAO
OwnerSUMITOMO HEAVY IND LTD