Cryogenic vacuum break thermal coupler with cross-axial actuation

• US 8,291,717 B2
• Filed: 05/02/2008
• Issued: 10/23/2012
• Est. Priority Date: 05/02/2008
• Status: Active Grant

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Radovinsky, Alexey L., Zhukovsky, Alexander
• Primary Examiner(s): Tyler, Cheryl J
• Assistant Examiner(s): Tudor, Valentin
• Application Number:
  US12/151,149
• Publication Number:
  US 20090272127A1
• Time in Patent Office: 1,635 Days
• Field of Search: 62/511, 62/6, 62/507, 626/06
• US Class Current: 62/50.7
• CPC Class Codes: F25D 19/006 Thermal coupling structure or interface
• CPC Class Codes: F28D 2021/0033 for cryogenic applications
• CPC Class Codes: F28F 2013/008 Variable conductance materials; Thermal switches

Abstract

A system and method to connect a cryocooler (refrigerator) to a superconducting magnet or cooled object allows for replacement without the need to break the cryostat vacuum or the need to warm up the superconducting magnet or other cooled object. A pneumatic or other type of actuator establishes a thermo-mechanical coupling. The mechanical closing forces are directed perpendicular (cross-axially) to the cryocooler axis and are not applied to the thin wall cryocooler body or to the thin cryostat walls or to the cooled object or to its shield. It is also possible that some of the compressive force be transferred to the cryocooler body. In that case, the extensions are designed so that the forces transferred to the cryocooler thermal stages do not exceed allowable stresses in the cryocooler stage. Additionally the device provides the possibility of easy inspection and cleaning of the thermal contacting surfaces of the cryostat cold and intermediate stations from the bonded chips of compressible gasket after the cryocooler retraction.

Claims

1. A coupler for thermally coupling a cooling device to an object to be cooled, the cooling device having at least one cooling stage, which extends along an axis, the coupler comprising:

a. a cold station configured to couple with a cold stage extension of a cooling device at a cold station interface and configured to connect with an object to be cooled;

b. the cold stage extension coupled to the cooling device cold stage, the cold stage extension terminating in two plates;

c. mechanically rigidly connected to the cold station, a cold station frame, having an actuator side and a thermal side which is arranged to face the cold station interface, all arranged such that the cold stage of the cooling device fits between the frame actuator side and the thermal side;

d. an actuator, comprising a linearly extendible member having two ends, a fixed end, coupled to the actuator side of the cold station frame and the other end arranged to contact and push, upon energization, the extension of the cold stage of the cooling device, toward the cold station interface, the actuator arranged to apply substantially equal and opposite cross-axial forces to the cold stage extension and the actuator side of the cold station frame, thereby forcing the cold stage extension from an uncoupled configuration into a coupled configuration with the cold stage extension contacting the cold station at the cold station interface, without any force being applied to the object to be cooled;

e. a cooling device vacuum enclosure, shaped and sized to house a cooling device vacuum around the cooling device, comprising the cold station; and

f. a cooled object vacuum enclosure, shaped and sized to house an object to be cooled, comprising the cold station, arranged to house a cooled object vacuum that is hydraulically independent from the cooling device vacuum.

2. The coupler of claim 1, a first plate comprising a relatively high thermal conductivity material and the second plate comprising a relatively low thermal conductivity material, as compared to the first plate.

3. The coupler of claim 2, the relatively low thermal conductivity material comprising a relatively stronger material than the high thermal conductivity material.

4. A coupler for thermally coupling a cooling device to an object to be cooled, the cooling device having at least one cooling stage, which extends along an axis, the coupler comprising:

a. a cold station configured to couple with a cold stage extension of a cooling device at a cold station interface and configured to connect with an object to be cooled;

b. the cold stage extension coupled to the cooling device cold stage;

c. mechanically rigidly connected to the cold station, a cold station frame, having an actuator side and a thermal side which is arranged to face the cold station interface, all arranged such that the cold stage of the cooling device fits between the frame actuator side and the thermal side;

d. an actuator arranged to apply substantially equal and opposite cross-axial forces to the cold stage extension and the actuator side of the cold station frame, thereby forcing the cold stage extension from an uncoupled configuration into a coupled configuration with the cold stage extension contacting the cold station at the cold station interface, without any force being applied to the object to be cooled;

e. a cooling device vacuum enclosure, shaped and sized to house a cooling device vacuum around the cooling device, comprising the cold station; and

f. a cooled object vacuum enclosure, shaped and sized to house an object to be cooled, comprising the cold station, arranged to house a cooled object vacuum that is hydraulically independent from the cooling device vacuum;

g. an intermediate temperature station configured to couple with an intermediate temperature stage extension of a cooling device at an intermediate temperature station interface and configured to thermally couple with an object to be cooled;

h. an intermediate stage extension, coupled to the cooling device intermediate stage;

i. mechanically rigidly connected to the intermediate temperature station, an intermediate temperature station frame, having an actuator side and a thermal station side, which is arranged to face the intermediate temperature station interface, all arranged such that the intermediate temperature stage of the cooling device fits between the intermediate temperature station frame actuator side and the thermal side; and

j. a second actuator, arranged to apply substantially equal and opposite cross-axial forces to the intermediate temperature stage extension and the actuator side of the intermediate temperature station frame, thereby forcing the intermediate temperature stage extension from an uncoupled configuration into a coupled configuration, with the intermediate temperature stage extension contacting the intermediate temperature station at the intermediate temperature station interface, without any force being applied to the object to be cooled.

5. The coupler of claim 4, the intermediate temperature stage extension being coupled to the intermediate stage in a manner that transfers no cross-axial force to the intermediate stage of the cooling device.

6. The coupler of claim 4, further wherein the intermediate temperature stage extension contacts the intermediate temperature station at the intermediate temperature station interface, in a manner that transfers no greater than negligibly small cross-axial stress to the intermediate stage of the cooling device.

7. A method to thermally couple a cooling device having at least one cooling stage that extends along an axis, to an object to be cooled, the method comprising the steps of:

a. providing a thermal coupler comprising;

i. a cold station configured to couple with a cold stage extension of a cooling device at a cold station interface and configured to connect with an object to be cooled;

ii. a cold stage extension coupled to the cooling device cold stage;

iii. mechanically rigidly connected to the cold station, a cold station frame, having an actuator side and a thermal side which is arranged to face the cold station interface, all arranged such that the cold stage of the cooling device fits between the frame actuator side and the thermal side;

iv. an actuator arranged to apply substantially equal and opposite cross-axial forces to the cold stage extension and the actuator side of the cold station frame, thereby forcing the cold stage extension from an uncoupled configuration into a coupled configuration, with the cold stage extension contacting the cold station at the cold station interface, without any force being applied to the object to be cooled;

v. a cooling device vacuum enclosure shaped and sized to house a cooling device vacuum around the cooling device, comprising the cold station; and

vi. a cooled object vacuum enclosure, shaped and sized to house an object to be cooled, comprising the cold station, arranged to house a cooled object vacuum that is hydraulically independent from the cooling device vacuum;

b. introducing the cooling device into the cooling device vacuum enclosure, and positioning the cold stage extension of the cooling device in an uncoupled position, cross-axially between the actuator side of the cold station frame and the thermal side of the cold station frame;

c. energizing the actuator, so that the actuator engages the cold stage extension, thereby forcing the cold stage extension from an uncoupled position, toward a coupled position, contacting the cold station at the interface without any force being applied to the object to be cooled.

8. The method of claim 7, the actuator being arranged to apply substantially equal forces, without any cross-axial force being applied to the cooling device, the step of energizing the actuator comprising energizing the actuator, so that it engages the cold stage extension, without any force being applied to the cooling device.

9. The method of claim 7, the actuator being arranged to apply substantially equal forces, without any cross-axial stress being applied to the cooling device greater than negligibly small cross-axial stress, the step of energizing the actuator comprising energizing the actuator, so that the actuator engages the cold stage extension, without any cross-axial stress greater than negligibly small cross-axial stress being applied to the cooling device.

10. The method to couple of claim 7, the actuator comprising a pneumatic actuator, the step of energizing the actuator comprising increasing the pressure of a gas provided to the actuator.

11. The method of claim 7, the step of providing a thermal coupler further comprising, providing an indium gasket, bonded to the cold stage extension.

12. The method of claim 11, further comprising the steps of:

a. de-energizing the actuator, so that the actuator applies no force to the cold stage extension;

b. pulling the cold stage extension away from the cold station, thereby opening a gap between the cold stage extension and the cold station;

c. removing the cooling device from the cooling device vacuum enclosure; and

d. visually inspecting the cold station at the location at which the indium gasket was forced by the cold stage extension to contact the cold station, to identify and then mechanically remove any chips of the gasket that may have become bonded to the cold station.

13. The method of claim 7, the actuator comprising a pneumatic actuator, the step of energizing the actuator comprising increasing the pressure of helium gas provided to the actuator.

14. The method to couple of claim 7, further comprising the step of establishing a vacuum within the cooling device vacuum enclosure.

15. The method to couple of claim 7, further comprising the step of activating the cooling device.

16. The method to couple of claim 15, the step of activating the cooling device taking place before the step of energizing the actuator.

17. The method to couple of claim 15, the step of activating the cooling device taking place after the step of energizing the actuator.

18. The method of claim 7, wherein:

a. the step of providing a coupler comprises providing a coupler further having;

i. an intermediate temperature station configured to couple with an intermediate temperature stage extension of the cooling device at an intermediate temperature station interface and configured to connect with the object to be cooled;

ii. an intermediate stage extension coupled to the cooling device intermediate temperature stage;

iii. mechanically rigidly connected to the intermediate temperature station, an intermediate temperature station frame, having an actuator side and a thermal side, which is arranged to face the intermediate temperature station interface, all arranged such that the intermediate temperature stage of the cooling device fits between the actuator support frame side and the thermal side; and

iv. an intermediate stage actuator arranged to apply substantially equal and opposite cross-axial forces to the intermediate temperature stage extension and the actuator side of the intermediate temperature station frame, thereby forcing the intermediate temperature stage extension from an uncoupled configuration into a coupled configuration, with the intermediate temperature stage extension contacting the intermediate temperature station at the intermediate temperature station interface, without any force being applied to the object to be cooled;

b. the method further comprising the steps of;

i. positioning the intermediate stage extension of the cooling device in an uncoupled position, cross-axially between the actuator side of the intermediate station frame and the thermal side of the intermediate station frame; and

ii. energizing the intermediate actuator, so that the actuator engages the intermediate stage extension, thereby forcing the intermediate stage extension from an uncoupled position, toward a coupled position, contacting the intermediate station at the interface without any force being applied to the object to be cooled.