阅读说明：本技术 用于低温冷却器热管理的系统和方法 (System and method for thermal management of cryocooler ) 是由 阿里·奥克 习海霞 斯图尔特·保罗·费尔特姆 马克·德拉克尚 于 2019-09-04 设计创作，主要内容包括：本发明题为“用于低温冷却器热管理的系统和方法”。本发明提供了一种热管理系统,该热管理系统包括冷头低温冷却器和冷却夹套。冷头低温冷却器被构造成能够操作地联接到MRI系统的氦容器,并且被构造成冷却MRI系统的超导磁体或热屏蔽罩中的至少一者。冷却夹套具有限定套筒外部的外表面,并且包括设置在由冷却夹套限定的套筒外部的径向内侧的通道。冷却夹套被构造成接收来自氦容器的蒸发气体以使其循环流过通道,由此冷却冷头低温冷却器。(The invention provides a system and method for thermal management of a cryocooler. The invention provides a thermal management system comprising a coldhead cryocooler and a cooling jacket. The coldhead cryocooler is configured to be operably coupled to a helium vessel of the MRI system and configured to cool at least one of a superconducting magnet or a thermal shield of the MRI system. The cooling jacket has an outer surface defining a sleeve exterior and includes a channel disposed radially inward of the sleeve exterior defined by the cooling jacket. The cooling jacket is configured to receive boil-off gas from the helium vessel to circulate it through the passages, thereby cooling the coldhead cryocooler.)

1. A thermal management system, comprising:

a coldhead cryocooler configured to be operably coupled to a helium vessel of a Magnetic Resonance Imaging (MRI) system, the coldhead cryocooler configured to cool at least one of a superconducting magnet or a thermal shield of the MRI system;

a cooling jacket having an outer surface defining a sleeve exterior, the cooling jacket comprising a channel disposed radially inward of the sleeve exterior defined by the cooling jacket, the cooling jacket configured to receive boil-off gas from the helium vessel to circulate through the channel, thereby cooling at least one of the cold-head cryocooler or cryocooler sleeve.

2. The thermal management system of claim 1, wherein the coldhead cryocooler comprises a first stage and a second stage, wherein the cooling jacket is disposed about at least one of the first stage or the second stage.

3. The thermal management system of claim 2, further comprising an adapter plate and a second stage sleeve, the adapter plate configured to join the cooling jacket and the second stage sleeve together.

4. The thermal management system of claim 1, wherein the channels define open channels without grooves.

5. The thermal management system of claim 1, wherein a cross-section of the channels defines a honeycomb arrangement.

6. The thermal management system of claim 1, wherein a cross-section of the channel defines an aperture arrangement.

7. The thermal management system of claim 1, further comprising an outer tube disposed around an exterior of the sleeve of the cooling jacket, the outer tube configured to receive boil-off gas from the helium vessel, the outer tube having an internal structure configured to act as a heat exchanger.

8. The thermal management system of claim 1, further comprising insulation surrounding at least a portion of an exterior of the coldhead cryocooler.

9. A method, comprising:

coupling a coldhead cryocooler to a helium vessel of an MRI system, the coldhead cryocooler configured to cool at least one of a superconducting magnet or a thermal shield of the MRI system;

providing a cooling jacket disposed about at least a portion of the coldhead cryocooler, the cooling jacket having an outer surface defining a sleeve exterior, the cooling jacket comprising a passage disposed radially inward of the exterior defined by the cooling jacket, the cooling jacket configured to receive boil-off gas from the helium vessel to circulate through the passage, thereby cooling the coldhead cryocooler.

10. The method of claim 9, wherein the coldhead cryocooler comprises a first stage and a second stage, the method comprising providing the cooling jacket around the first stage and/or the second stage.

11. The method of claim 10, wherein the coldhead cryocooler comprises an adapter plate and a second stage sleeve, the method comprising joining the cooling jacket to the second stage sleeve via the adapter plate.

12. The method of claim 9, further comprising additive manufacturing an open channel without grooves within the channel.

13. The method of claim 9, further comprising additively manufacturing the channel to have a cross-section defining a honeycomb arrangement.

14. The method of claim 9, further comprising additively manufacturing the channel to have a cross-section defining an aperture arrangement.

15. The method of claim 9, further comprising disposing an outer tube around the sleeve exterior of the cooling jacket, the outer tube configured to receive boil-off gas from the helium vessel, the outer tube having an internal structure.

16. The method of claim 9, further comprising providing insulation around at least a portion of an exterior of the coldhead cryocooler.

17. The method of claim 16, further comprising: disposing a cover around the at least a portion of the exterior of the coldhead cooler, wherein a volume is defined between the cover and the exterior of the coldhead cooler; filling the volume with the insulation; and removing the cover.

18. A thermal management system, comprising:

a cold-head cryocooler configured to be operably coupled to a helium vessel of an MRI system, the cold-head cryocooler configured to cool at least one of a superconducting magnet or a thermal shield of the MRI system;

a cooling member coupled to the coldhead cryocooler, the cooling member including a passage configured to receive the boil-off gas from the helium vessel to circulate it therethrough, thereby cooling the coldhead cryocooler, wherein the passage includes an internal cross-section configured to act as a heat exchanger.

19. The thermal management system of claim 18, wherein the cooling member comprises a cooling jacket having an outer surface defining a sleeve exterior, the channel being disposed in the cooling jacket and radially inward of the sleeve exterior defined by the cooling jacket.

20. The thermal management system of claim 18, wherein the coldhead cryocooler comprises a cooling jacket having an outer surface defining a sleeve exterior, wherein the cooling means comprises an outer tube disposed around the sleeve exterior of the cooling jacket, the channel being disposed in the outer tube, the outer tube being configured to receive the boil-off gas from the helium vessel.

Background

The subject matter disclosed herein relates generally to apparatus and methods for cooling an MRI system, such as during periods of power outage of the MRI system.

For cryogenically cooled MR magnets, helium used to cool the magnet may evaporate when the system including the MR magnet is powered down. For example, the system may be powered down for transport from one location to another. When the system is powered down, the helium may heat up and evaporate, resulting in loss of helium.

Disclosure of Invention

In one exemplary embodiment, a thermal management system is provided that includes a coldhead cryocooler and a cooling jacket. The coldhead cryocooler is configured to be operably coupled to a helium vessel of the MRI system and configured to cool at least one of a superconducting magnet coil or a thermal shield of the MRI system. The cooling jacket has an outer surface defining a sleeve exterior and includes a channel disposed radially inward of the sleeve exterior defined by the cooling jacket. The cooling jacket is configured to receive boil-off gas from the helium vessel to circulate it through the passages, thereby cooling the coldhead cryocooler.

In another exemplary embodiment, a method is provided that includes coupling a coldhead cryocooler to a helium vessel of an MRI system. The cold head cryocooler is configured to cool at least one of a superconducting magnet or a thermal shield of the MRI system. The method also includes providing a cooling jacket disposed about at least a portion of the coldhead cryocooler. The cooling jacket has an outer surface defining an exterior of the sleeve and includes a channel disposed radially inward of the exterior defined by the cooling jacket. The cooling jacket is configured to receive boil-off gas from the helium vessel to circulate it through the passages, thereby cooling the coldhead cryocooler.

In another exemplary embodiment, a thermal management system is provided that includes a coldhead cryocooler and a cooling member. The coldhead cryocooler is configured to be operably coupled to a helium vessel of the MRI system and configured to cool at least one of a superconducting magnet or a thermal shield of the MRI system. A cooling member is coupled to the coldhead cryocooler and includes a passage configured to receive the boil-off gas from the helium vessel to circulate it through the passage, thereby cooling the coldhead cryocooler. The channel includes an interior cross-section.

Drawings

Fig. 1 provides a schematic diagram of a thermal management system according to various embodiments.

Fig. 2 provides a side view of aspects of a thermal management system according to various embodiments.

Fig. 3A provides a side cross-sectional view of a coldhead sleeve according to various embodiments.

Fig. 3B provides an enlarged view of a portion of fig. 3A.

Fig. 4 provides a side cross-sectional view of a coldhead sleeve according to various embodiments.

Fig. 5A provides a cross-sectional view of a channel according to various embodiments.

Fig. 5B provides a cross-sectional view of a channel according to various embodiments.

Fig. 5C provides a cross-sectional view of a channel according to various embodiments.

Fig. 5D provides a cross-sectional view of a channel according to various embodiments.

Fig. 5E provides a cross-sectional view of a channel according to various embodiments.

Fig. 5F provides a cross-sectional view of a channel according to various embodiments.

Fig. 5G provides a cross-sectional view of a channel according to various embodiments.

Fig. 6 provides a side view of aspects of a thermal management system according to various embodiments.

Figure 7 provides a perspective view of a thermal management system according to various embodiments.

Fig. 8 provides a flow diagram of a method according to various embodiments.

Fig. 9 provides a schematic block diagram of an MRI system according to various embodiments.

Detailed Description

The following detailed description of certain embodiments will be better understood when read in conjunction with the appended drawings. To the extent that the figures illustrate diagrams of the functional blocks of various embodiments, the functional blocks are not necessarily indicative of the division between hardware. It should be understood that the various embodiments are not limited to the arrangements and instrumentality shown in the drawings.

As used herein, an element or step recited in the singular and proceeded with the word "a" or "an" should be understood as not excluding plural said elements or steps, unless such exclusion is explicitly recited. Furthermore, references to "one embodiment" are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. Furthermore, unless explicitly stated to the contrary, embodiments "comprising" or "having" one or more elements having a particular property may include additional elements not having that property.

Various embodiments provide systems and methods for improving cooling of an MRI system and/or reducing helium loss in the event of a power outage of a coldhead cryocooler, such as MRI system transport or coldhead failure. Various embodiments provide for the use of a coldhead sleeve having passages for the boil-off gas to improve the operation of a coldhead cryocooler. Various embodiments provide a heat exchanger cross-section of a coldhead sleeve (or other passage such as an outer tube) using conventional manufacturing methods such as welding and brazing or unconventional manufacturing methods such as additive manufacturing methods. In various embodiments, the coldhead sleeve (e.g., the first stage of the coldhead sleeve) is cooled with the boil-off gas by using a heat exchanger on the sleeve body. Additionally or alternatively, various embodiments use insulation around the portion of the coldhead cryocooler that extends beyond the housing. Various embodiments receive boil-off gas from the helium vessel to circulate it through the channels, thereby cooling the coldhead cryocooler and associated cryocooler sleeve by intercepting heat from the outside, which may result in reduced helium loss.

Technical implementations of various embodiments include improving cooling of an MRI system (e.g., during a power-off state). Technical implementations of various embodiments include reducing helium loss during a power-off state and reducing costs for recharging helium in a helium vessel.

Figure 1 provides a perspective view of a thermal management system 100 formed in accordance with various embodiments. The thermal management system 100 includes a coldhead cryocooler 110 and a cooling structure 120. The thermal management system 100 shown is operably coupled to a helium vessel 104 of a Magnetic Resonance Imaging (MRI) system 102. In general, the thermal management system 100 is used to cool aspects of the MRI system 102 (e.g., at least one of the superconducting magnet or the thermal shield 103 of the MRI system 102) during a powered down state of the MRI system (e.g., during a powered down state of a cryocooler of a magnet of the MRI system).

In various embodiments, helium vessel 104 is utilized to cryogenically cool coils on a superconducting magnet of MRI system 102. During operation of the coldhead cryocooler 110, the coldhead cryocooler 110 (which may be disposed within the sleeve) serves to recondense the vaporized cryogen to continuously cool the superconducting magnet coils and/or the thermal shield 103 of the MRI system 102. For example, the vaporized refrigerant may be provided to the recondenser 116 via conduit 118. During use of the coldhead cryocooler 110, the coldhead sleeve 111 acts as a vacuum barrier between the vacuum chamber and the external environment to maintain a vacuum seal. The housing 117 in the illustrated embodiment is disposed around a portion of the coldhead cryocooler 110 and cooperates with the coldhead sleeve 111 to provide a vacuum.

As seen in fig. 1, cryocooler 110 is shown to include a first stage 112 and a second stage 114. The first stage 112 may have a higher operating temperature than the second stage 114. For example, the first stage may have an operating temperature of about 40 degrees kelvin, and the second stage 114 may have an operating temperature of about 4 degrees kelvin.

Generally, cooling member 120 is configured to receive the boil-off gas from helium vessel 104 and act as a heat exchanger that cools coldhead cryocooler 110 with the boil-off gas (e.g., by cooling a sleeve surrounding the cryocooler). For example, in various embodiments, cooling member 120 includes a channel configured to receive boil-off gas from helium vessel 104 to circulate it through the channel, thereby cooling coldhead cryocooler 110. In various embodiments, the channel has an internal cross-section configured to act as a heat exchanger. Various different fabrication techniques may be employed to form the cross-section. As one example, the internal cross-section may be formed by additive manufacturing (e.g., 3D printing). For example, additive manufacturing may be employed to provide complex internal shapes to direct evaporative gas flow that are not possible or practical with other manufacturing techniques. In other embodiments, the internal cross-section may be formed by alternative manufacturing techniques such as welding, brazing, or casting.

The cooling member 120 is schematically shown as a block in fig. 1. It should be noted, however, that in various embodiments, the cooling member is a generally tubular structure that surrounds all or a portion of the coldhead cryocooler 110. For example, the cooling member may comprise a cylindrical sleeve surrounding all or a portion of the coldhead cryocooler 110, and/or may comprise tubing surrounding (e.g., helically wound) all or a portion of the coldhead cryocooler 110.

In various embodiments, the cooling member 120 is configured as a cooling sleeve or jacket. The cooling jacket in various embodiments defines a generally cylindrical structure having inner and outer walls extending along the length of the coldhead cryocooler and surrounding the coldhead cryocooler, and a passage extending in the volume between the inner and outer walls that receives the boil-off gas. The outer wall and the inner wall may each define a continuous cylindrical surface. For example, fig. 2 provides a perspective view of an embodiment of a thermal management system 100 including a cooling jacket 122. The cooling jacket 122 is an example of the cooling member 120. In various embodiments, the cooling jacket 122 forms a portion of the coldhead sleeve 111. For example, in some embodiments, the cooling jacket 122 may be integrally formed with the coldhead sleeve 111, or may be joined to the coldhead sleeve.

The illustrated cooling jacket 122 includes an outer surface 124 defining a sleeve exterior 126. In addition, the illustrated cooling jacket 122 includes a channel 128 disposed radially inward of a sleeve exterior 126 (e.g., defined by the outer surface 124) defined by the cooling jacket 122. Cooling jacket 122 is configured to receive boil-off gas from helium vessel 104 to circulate it through passage 128, thereby cooling the coldhead cryocooler. In the illustrated embodiment, the cooling jacket 122 includes channel ports 121 that can be used as inlets and outlets for boil-off gas. It should be noted that the access port may be of any shape and orientation. In various embodiments, the cooling jacket is made of a thermally conductive metal (such as, by way of example, aluminum, copper, or stainless steel). It should be noted that, in various embodiments, the cooling jacket 122 (or aspects thereof) may be constructed by any type of unconventional and conventional manufacturing method.

Fig. 3A provides a side cross-sectional view of the cooling jacket 122, and fig. 3B provides an enlarged view of a portion of fig. 3A. As best seen in fig. 3A or 3B, the cooling jacket 122 includes an inner surface 125 spaced a distance from the outer surface 124 to define a volume through which the channel 128 passes. Thus, fluid (e.g., boil-off gas) passing through the passage 128 may be used to remove heat from a cryocooler disposed radially inward of the inner surface 125. In the illustrated embodiment, a groove 129 is defined in the space between the inner surface 125 and the outer surface 124 to form a channel. The grooves 129 may cooperate to form the channel 128 and/or one or more additional channels. During manufacture, other structures may be disposed in the space between the inner surface 125 and the outer surface 124 to define grooves 129 and/or to direct flow through the channels 128.

In various embodiments, a cooling jacket 122 may be disposed about the first stage 112 (or portion thereof) and/or the second stage 114 (or portion thereof). For example, fig. 4 shows a side cross-sectional view of an embodiment in which a cooling jacket 122 (which includes channels 128 for flow of boil-off gas) is disposed around the first stage 112. As seen in fig. 4, the thermal management system 100 of the illustrated example further includes an adapter plate 130 and a second stage sleeve 140. The adapter plate 130 may be formed as a ring that provides an interface between the second stage sleeve 140 and the cooling jacket 122. In the illustrated example, the cooling jacket 122 is configured to be disposed about the first stage 112, and the second stage sleeve 140 is configured to be disposed about the second stage 114. The adapter plate 130 is configured to join the cooling jacket 122 and the second stage sleeve 140 together. For example, the first stage tubes 132 may be engaged with the second stage sleeve 140 using the adapter plate 130, and the cooling jackets 122 may be disposed around the first stage tubes 132. The first stage assembly or component (cooling jacket and first stage tubes 132) may be joined to the adapter plate 130 and second stage 140, for example, by brazing, welding, or additive manufacturing.

As described above, in various embodiments, the channels 128 (or aspects thereof) may be formed in various embodiments to provide complex internal shapes between the inner surface 125 and the outer surface 124 of the cooling jacket or within the tubing that wraps around one or more aspects of the coldhead cryocooler 110. As one example, in various embodiments, additive manufacturing may be used to help provide complex channels for improved thermal performance. Additionally or alternatively, in various embodiments, other manufacturing techniques may be used. Fig. 5A-5G illustrate examples of channel shapes formed according to various embodiments, wherein the channels are configured to function as heat exchangers in various embodiments.

Fig. 5A shows an example in which the channel 128 defines an open channel 510 that does not include a groove. Alternatively, open channel 510 includes extension 512 that is cantilevered from inner surface 513 or outer surface 514 (e.g., extension 512 extends from one of inner surface 513 or outer surface 514 without reaching the other of inner surface 513 or outer surface 514). The extensions in various embodiments may be in other configurations and/or disposed at different angles.

Fig. 5B shows an example in which the cross-section of the channels 128 defines a honeycomb arrangement. As seen in fig. 5B, the honeycomb walls 520 cooperate to define honeycomb cells 522. In some embodiments, the honeycomb cells may be closed laterally and joined in a spiral arrangement. In the illustrated embodiment, the cells 522 include openings 524 that allow lateral flow between adjacent cells 522.

Fig. 5C shows an example in which a cross-section of the channel 128 defines an aperture arrangement. The aperture arrangement includes cells 530 defined by walls 532 having openings 534 to allow flow between adjacent cells.

Fig. 5D shows an example in which the channels 128 are formed by a continuous spiral of closed cells 540 (e.g., fins 542 extending from the inner surface 543 to the outer surface 544). Fig. 5E shows an example in which the channels 128 are formed by an interrupted spiral of closed cells 550 (through which the boil-off gas flows), separated by spaces 552 that do not flow through the boil-off gas. The angle between the walls of the cells may vary in different embodiments.

It should be noted that the inner surface 125 and/or the outer surface 124 of the cooling jacket 122 need not be straight. For example, fig. 5F shows an exemplary embodiment in which the outer surface 560 is tapered along an axis 562 extending in the length direction of the cooling jacket 122. Additionally or alternatively, the inner surface 565 can be tapered. Fig. 5G shows an exemplary embodiment in which the outer surface 570 is stepped, having a first portion 572 that is farther from the inner surface ratio 571 than a second portion 573 from the inner surface 571. It should be noted that with reference to fig. 5A-5G, the illustrated examples are provided by way of example, and variations, combinations, or other arrangements of the illustrated examples can be used in various embodiments. The particular configuration (e.g., dimensions, arrangement, etc.) may be selected for the particular heat exchange needs of a given application.

In addition to or alternatively to a sleeve comprising channels for boil-off gas located radially inside the sleeve exterior, in various embodiments the channels for boil-off gas may be provided by tubes disposed radially outside the sleeve exterior. For example, fig. 6 provides a side view of an example of the thermal management system 100 in which the cooling member 120 includes an outer tube 150. In the illustrated example, the outer tube 150 is disposed about the sleeve exterior 126 of the coldhead sleeve 111. It should be noted that the outer tube 150 may be placed around the coldhead sleeve 111 at either or both of the first stage 112 or the second stage 114 (or portions thereof). Further, it should be noted that in various embodiments, the outer tube 150 may be disposed within the vacuum defined by the housing 117 and/or outside the vacuum defined by the housing 117. Outer tube 150 is configured to receive boil-off gas from helium vessel 104 (e.g., passage 128 extends through the interior of the outer tube). In various embodiments, the outer tube 150 has an additive manufactured internal structure (e.g., the honeycomb arrangement of fig. 5B, the open cell arrangement of fig. 5C). Other fabrication techniques may be used in various embodiments. In various embodiments, the outer tube 150 may be disposed around the cooling jacket 122.

In addition or alternatively to the sleeves and tubes discussed in connection with fig. 2-6, in various embodiments, the thermal management system includes insulation. Fig. 7 provides a perspective view of thermal management system 100 in which insulation 700 (represented by hatching) is provided around at least a portion of the exterior of coldhead cryocooler 110. In the illustrated example, insulation is provided around the portion of the coldhead cryocooler 110 that is located outside of the housing 117. For example, a temporary cover may be disposed around the coldhead cryocooler 110 outside of the housing 117, an insulation 700 is introduced into the temporary cover to fill the space between the temporary cover and the coldhead cryocooler 110, and the cover is removed.

Fig. 8 provides a flow chart of a method 800. For example, the method 800 (or aspects thereof) may employ or be performed by structures or aspects of various embodiments discussed herein (e.g., systems and/or methods and/or process flows). In various embodiments, certain steps may be omitted or added, certain steps may be combined, certain steps may be performed simultaneously, certain steps may be split into multiple steps, certain steps may be performed in a different order, or certain steps or series of steps may be re-performed in an iterative fashion.

At 802, a coldhead cryocooler (e.g., coldhead cryocooler 110) is coupled to a helium vessel of an MRI system (e.g., helium vessel 104 of MRI system 102). The cold head cryocooler is configured to cool at least one of a superconducting magnet or a thermal shield of the MRI system. For example, a coldhead cryocooler may be used to cool the vaporized cryogen, which is then returned to the helium vessel. The coldhead cryocooler may be mechanically or fluidically coupled directly or indirectly to the helium vessel. For example, a coldhead cryocooler may be indirectly mechanically mounted to a helium vessel by mounting to a structure and then mounting the structure to the helium vessel. A coldhead cryocooler is fluidly coupled (e.g., via a conduit) to the helium vessel to receive vaporized cryogen from the helium vessel.

At 804, a cooling jacket (e.g., cooling jacket 122) is disposed around at least a portion of the coldhead cryocooler. The cooling jacket has an outer surface defining a sleeve exterior and includes a channel disposed radially inward of the sleeve exterior. (see, e.g., fig. 3A and 3B.) the cooling jacket is configured to receive boil-off gas from the helium vessel to circulate it through the channels, thereby cooling the coldhead cryocooler. It should be noted that, as discussed herein, in various embodiments, other cooling members (e.g., outer tubes, such as outer tube 150) and/or insulation may additionally or alternatively be used.

In various embodiments, the cooling jacket comprises channels formed or defined to act as heat exchangers. In some embodiments, the channels are formed using additive manufacturing. In some embodiments, open channels are formed without trenches. In some embodiments, the channels are additively manufactured to have a cross-section that defines a honeycomb arrangement. As another example, in some embodiments, the channels are additively manufactured to have a cross-section that defines an aperture arrangement.

As described herein, in various embodiments, a cooling jacket is disposed around the first stage of the coldhead cryocooler. In the illustrated example, at 808, a cooling jacket is disposed about the first stage. For example, at 810, the cooling jacket is joined to a second stage sleeve (e.g., second stage sleeve 140) with an adapter plate (e.g., adapter plate 130).

At 812, an outer tube (e.g., outer tube 150) is disposed around the sleeve exterior of the cooling jacket. The outer tube is configured to receive boil-off gas from the helium vessel and has an additively manufactured internal structure to define a channel through which the boil-off gas flows. It should be noted that in some embodiments, the outer tube may alternatively be used for a cooling sleeve as discussed herein. Generally, the outer tube is wound in a helical fashion around the outside of the coldhead sleeve. In various embodiments, the exterior may wrap around the first stage (or portion thereof) and/or the second stage (or portion thereof) of the coldhead cryocooler.

At 814 of the illustrated embodiment, insulation is disposed around at least a portion of the exterior of the coldhead cryocooler. (see, e.g., fig. 7 and related discussion.) insulation may contact and surround the exterior of the coldhead cryocooler. It should be noted that in various embodiments, insulation may be used in addition to or in the alternative to using a cooling jacket and/or an outer tube. In the example shown, at 816, a cover is disposed around a portion of the exterior of the cold head cryocooler to be insulated (e.g., around the portion of the cold head cryocooler exterior of the enclosure defining the vacuum chamber). The cover defines a volume between the cover and an exterior of the coldhead cryocooler. At 818, the volume between the cover and the exterior is filled with insulation, and at 820, the cover is removed. For example, in some embodiments, liquid polyurethane insulation may be provided, or insulation may be provided in a bag that is placed around the exterior of the coldhead cryocooler (more than one bag may be used in various embodiments). The cover may then provide a temporary enclosure during which insulation is injected and allowed to cure.

As discussed herein, the various methods and/or systems described herein (and/or aspects thereof) may be implemented in connection with an MRI system. For example, fig. 9 illustrates various major components of an MRI system 10 formed in accordance with various embodiments. The operation of the system is controlled by an operator console 12, which includes a keyboard or other input device 13, a control panel 14, and a display 16. Console 12 communicates through link 18 with a separate computer system 20 that enables an operator to control the generation and display of images on screen 16. The computer system 20 includes a plurality of modules that communicate with each other through a backplane 20 a. These modules include an image processor module 22, a CPU module 24, and a memory module 26 (a frame buffer known in the art for storing image data arrays). The computer system 20 is linked to disk storage 28 and tape drives 30 for storing image data and programs, and communicates with a separate system controller 32 through a high speed serial link 34. The input device 13 may comprise a mouse, joystick, keyboard, trackball, touch-activated screen, light wand, voice controller, or any similar or equivalent input device and may be used for interactive geometry requirements.

System controls 32 comprise a set of modules connected together by a backplane 32 a. These modules include a CPU module 36 and a pulse generator module 38, which is connected to the operator console 12 by a serial link 40. Through link 40, the system controller 32 receives commands from the operator indicating the scan sequence to be performed. The pulse generator module 38 operates the system components to perform the desired scan sequence and generates data indicative of the time, intensity and shape of the generated RF pulses and the time and length of the data acquisition window. The pulse generator module 38 is connected to a set of gradient amplifiers 42 to indicate the timing and shape of the gradient pulses generated during the scan. The pulse generator 38 may also receive patient data from a physiological acquisition controller 44 that receives signals from a plurality of different sensors connected to the patient or subject, such as ECG signals from electrodes attached to the patient. And finally, the pulse generator 38 is connected to a scan room interface circuit 46 that receives signals associated with the patient and magnet system from various sensors. The patient positioning system 48 also receives commands through the scan room interface circuit 46 to move the patient to a desired position for scanning.

The gradient waveform generated by the pulse generator module 38 is applied to the waveform having a gradient G_x、G_yAnd G_zGradient amplifier system 42 of amplifiers. Each gradient amplifier excites a corresponding physical gradient coil in a gradient coil assembly generally designated 50 to produce magnetic field gradients used for spatially encoding acquired signals. The gradient coil assembly 50 and an RF shield (not shown) form part of a magnet assembly 52 that includes a polarizing magnet 54 and an RF coil assembly 56. A transceiver module 58 in the system controller 32 generates pulses that are amplified by an RF amplifier 60 and coupled to the RF coil assembly 56 through a transmit/receive switch 62. The resulting signals emitted by the excited nuclei in the patient may be sensed by the same RF coil assembly 56, or portions thereof, and coupled through the transmit/receive switch 62 to a preamplifier 64. The amplified MR signals are demodulated, filtered and digitized in a receiver portion of the transceiver 58. The transmit/receive switch 62 is controlled by a signal from the pulse generator module 38 to electrically connect the RF amplifier 60 to the coil assembly 56 during the transmit mode and to connect the RF amplifier 60 to the coil assembly 56 during the receive modeThe preamplifier 64 is connected to the coil assembly 56. The transmit/receive switch 62 may also enable a separate RF coil (e.g., a surface coil) to be used in either the transmit or receive mode. The magnet assembly 52 may be cryogenically cooled. For example, the magnet assembly 52 of the illustrated embodiment is disposed within a helium vessel 53 that utilizes helium to cryogenically cool the magnet assembly 52. A heat shield 55 is also provided around the magnet assembly 52.

The MR signals picked up by the selected RF coils are digitized by the transceiver module 58 and transferred to a memory module 66 in the system controller 32. The scan is complete when the array of raw k-space data is acquired in the memory module 66. For each image to be reconstructed, the raw k-space data is rearranged into separate k-space data arrays, and each of these separate k-space data arrays is input to an array processor 68, which operates to fourier transform the data into an image data array. The image data is transferred to the computer system 20 via the serial link 34 for storage in a memory, such as the hard disk storage device 28. In response to commands received from the operator console 12, the image data may be archived in long-term storage, such as on a tape drive 30, or may be further processed and transferred to the operator console 12 by the image processor 22 and presented on the display 16.

It should be noted that the various embodiments may be implemented in hardware, software, or a combination thereof. Various embodiments and/or components (e.g., modules or components and controllers therein) may also be implemented as part of one or more computers or processors. The computer or processor may include a computing device, an input device, a display unit, and an interface, for example, for accessing the internet. The computer or processor may include a microprocessor. The microprocessor may be connected to a communication bus. The computer or processor may also include memory. The memory may include Random Access Memory (RAM) and Read Only Memory (ROM). The computer or processor may also include a storage device, which may be a hard disk drive or a removable storage drive such as a solid state drive, optical disk drive, or the like. The storage device may also be other similar means for loading computer programs or other instructions into the computer or processor.

As used herein, the term "computer" or "module" may include any processor-based or microprocessor-based system including systems using microcontrollers, Reduced Instruction Set Computers (RISC), ASICs, logic circuits, and any other circuit or processor capable of executing the functions described herein. The above examples are exemplary only, and are thus not intended to limit in any way the definition and/or meaning of the term "computer".

The computer or processor executes a set of instructions stored in one or more storage elements in order to process input data. The storage elements may also store data or other information as desired or needed. The storage elements may be in the form of information sources or physical memory elements within the processor.

The set of instructions may include various commands that instruct the computer or processor as a processor to perform specific operations, such as the methods and processes of the various embodiments. The set of instructions may be in the form of a software program. The software may be in various forms, such as system software or application software, and may be embodied as tangible and non-transitory computer readable media. Further, the software may be in the form of a collection of separate programs or modules, a program module within a larger program or a portion of a program module. The software may also include modular programming in the form of object-oriented programming. The processing of input data by a processing machine may be in response to an operator command, or in response to the results of a previous process, or in response to a request made by another processing machine.

As used herein, a structure, limitation, or element that is "configured to" perform a task or operation is formed, configured, or adjusted on a particular structure in a manner that corresponds to the task or operation. For the purposes of clarity and avoidance of doubt, an object that can only be modified to perform a task or operation is not "configured to" perform the task or operation as used herein. Rather, as used herein, the use of "configured to" refers to structural adaptations or characteristics and to structural requirements of any structure, limitation, or element described as "configured to" perform a task or operation. For example, a processor unit, processor, or computer that is "configured to" perform a task or operation may be understood as being specifically configured to perform the task or operation (e.g., having one or more programs or instructions stored thereon or used therewith that are customized or intended to perform the task or operation, and/or having an arrangement of processing circuitry that is customized or intended to perform the task or operation). For the purposes of clarity and avoidance of doubt, a general purpose computer (which may be "configured to" perform a task or operation, if appropriately programmed) is not "configured to" perform the task or operation unless or until specifically programmed or structurally modified to perform the task or operation.

As used herein, the terms "software" and "firmware" are interchangeable, and include any computer program stored in memory for execution by a computer, including RAM memory, ROM memory, EPROM memory, EEPROM memory, and non-volatile RAM (NVRAM) memory. The above memory types are exemplary only, and are thus not limiting as to the types of memory usable for storage of a computer program.

It is to be understood that the above description is intended to be illustrative, and not restrictive. For example, the above-described embodiments (and/or aspects thereof) may be used in combination with each other. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the various embodiments without departing from the scope thereof.

While the dimensions and types of materials described herein are intended to define the parameters of the various embodiments, they are by no means limiting and are exemplary only. Many other embodiments will be apparent to those of skill in the art upon reading the above description. The scope of various embodiments should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms "including" and "in … are used as the plain-chinese equivalents of the respective terms" comprising "and" wherein ". Furthermore, in the following claims, the terms "first," "second," and "third," etc. are used merely as labels, and are not intended to impose numerical requirements on their objects. Furthermore, the limitations of the following claims are not written in a device-plus-function format, and are not intended to be interpreted based on 35u.s.c. § 112(f), unless and until such claim limitations explicitly use the phrase "device for …," followed by a functional statement without other structure.

This written description uses examples to disclose various embodiments, including the best mode, and also to enable any person skilled in the art to practice various embodiments, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the various embodiments is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.