Liquid-helium-free superconducting magnet for a rotating gantry

Abstract

The application provides a liquid-helium-free superconducting magnet for a rotating gantry, and relates to the technical field of superconducting magnets, and comprises a superconducting coil framework, which is a circular ring structure and is made of non-metallic G10 material; a superconducting coil assembly, which is wound on the surface of the superconducting coil framework; a cold conducting assembly, which is a ring-shaped conduction cooling structure, is nested with the superconducting coil framework, and is configured to transfer cold energy to the surface of the superconducting coil assembly to cool the superconducting coil assembly; a cold conducting copper braided belt, one end of which is connected with the cold conducting assembly; a two-stage cold conducting conversion plate, which is connected with the other end of the cold conducting copper braided belt; and a refrigerator, which is connected with the two-stage cold conducting conversion plate; wherein the cold energy is transferred to the two-stage cold conducting conversion plate through the cold head of the refrigerator, and then is transferred to the cold conducting assembly through the cold conducting copper braided belt.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of superconducting magnet, and particularly relates to a liquid-helium-free superconducting magnet for a rotating gantry. BACKGROUND

[0002] Miniaturization and light weight of the rotating gantry is the development direction of the new generation of ion radiotherapy device. The superconducting magnet has the characteristics of small volume, light weight, low power consumption and high magnetic field strength, which can reduce the deflection radius of the ion and the size of the rotating gantry. Therefore, it is an inevitable trend to apply the superconducting magnet technology to the ion radiotherapy device.

[0003] The superconducting magnet is made of superconducting material which has the characteristic of reducing resistance to zero at a certain temperature. The superconducting magnet generally works in the liquid helium temperature zone and is cooled by liquid helium immersion. However, for the rotating gantry, the liquid-helium-free superconducting magnet cannot guarantee stable operation. The rotating gantry usually adopts the liquid-helium-free superconducting magnet, which relies on the small GM (Gifford-Mcmahon) cryogenic refrigerator to cool down, and the whole superconducting coil is cooled to the superconducting state through the conduction cooling mode.

[0004] At present, the structure connecting the cryogenic refrigerator and the superconducting coil (including the coil skeleton) is mostly made of high-purity oxygen-free copper, and the coil skeleton is mostly made of aluminum alloy or stainless steel and other metal materials. In order to ensure that the cooling reaches the design requirements, a certain redundancy design will be adopted, and a large amount of oxygen-free copper plate and metal skeleton will greatly increase the weight, volume and cost of the magnet. More seriously, the copper plate and the metal skeleton will generate eddy current in the alternating magnetic field (pulse operation), which will increase the total AC loss of the magnet and increase the cooling difficulty. SUMMARY

[0005] In view of the above technical problems, the present application provides a liquid-helium-free superconducting magnet for a rotating gantry, which at least partially solves the above technical problems.

[0006] Based on this, the present application provides a liquid-helium-free superconducting magnet for a rotating gantry, comprising: a superconducting coil skeleton, which is a circular ring structure and is made of non-metal G10 material; a superconducting coil assembly, which is wound on the surface of the superconducting coil skeleton; a cold conducting assembly, which is a ring-shaped conduction cooling structure and is nested with the superconducting coil skeleton, and is configured to transfer cold energy to the surface of the superconducting coil assembly to cool the superconducting coil assembly; a cold conducting copper braid, one end of which is connected with the cold conducting assembly; a secondary cold conducting conversion plate, which is connected with the other end of the cold conducting copper braid; a refrigerator, which is connected with the secondary cold conducting conversion plate; wherein the cold energy is transferred to the secondary cold conducting conversion plate through the cold head of the refrigerator, and then transferred to the cold conducting assembly through the cold conducting copper braid.

[0007] According to an embodiment of the present disclosure, the superconducting coil former comprises: a superconducting quadrupole coil G10 former, a superconducting dipole coil G10 former, and a former connecting end plate; wherein the superconducting quadrupole coil G10 former and the superconducting dipole coil G10 former are fixedly connected by the former connecting end plate on both sides of the end portion after being nested.

[0008] According to an embodiment of the present disclosure, the outer surface of the superconducting coil former is provided with a wire groove, and the superconducting coil assembly is formed after the superconducting cable is wound along the wire groove and then epoxy cured.

[0009] According to an embodiment of the present disclosure, the cooling assembly comprises: an end cooling plate, an axial cooling belt, and a radial cooling ring; the axial cooling belt is distributed along the axial direction of the superconducting coil former to form an axial cooling channel; the end cooling plate is distributed at a predetermined angle at the end portion of the superconducting coil former and is integrally connected with the axial cooling belt; the radial cooling ring is wound along the radial direction of the superconducting coil former and is spaced apart along the axial direction to form a radial cooling channel; and the axial cooling belt and the radial cooling ring are connected at the intersection position.

[0010] According to an embodiment of the present disclosure, the axial cooling belt is composed of a thin copper belt, and the radial cooling ring is composed of a plurality of thin aluminum belts.

[0011] According to an embodiment of the present disclosure, the cooling assembly further comprises: a middle cooling plate, the middle cooling plate being connected with the radial cooling ring through the superconducting coil former.

[0012] According to an embodiment of the present disclosure, the middle cooling plate is composed of a plurality of thin copper belts stacked together.

[0013] According to an embodiment of the present disclosure, the axial cooling belt and the radial cooling ring are configured to adjust the eddy current loss of the liquid-helium-free superconducting magnet by adjusting the size parameters.

[0014] According to an embodiment of the present disclosure, one end of the cooling copper braided belt is connected with the end cooling belt and the middle cooling plate.

[0015] According to an embodiment of the present disclosure, the liquid-helium-free superconducting magnet further comprises: a thermostat, and the refrigerator is fixed on the maintenance tower of the thermostat.

[0016] According to the liquid-helium-free superconducting magnet for the rotating gantry provided by the embodiment of the present disclosure, at least the following beneficial effects are achieved:

[0017] Since the superconducting coil former is made of non-metallic G10 material, the non-metallic former does not generate eddy current during pulse operation, which can greatly reduce the alternating current loss of the magnet as a whole. Moreover, the non-metallic G10 material can greatly reduce the total weight of the superconducting magnet, thereby meeting the use requirement of lightweight structure of the rotating gantry as a whole.

[0018] The axial cooling channel is formed by the axial cooling belt of the cooling assembly, the radial cooling channel is formed by the radial cooling ring, and the conduction cooling structure of the main cooling channel is arranged at the end of the magnet and the pole head, so that the high-efficiency cooling in the absence of liquid helium can be realized, and the stability of the rotating superconducting magnet of the rotating gantry during rotation can be ensured.

[0019] The radial cooling ring is radially wound and spaced along the axial direction, the radial cooling ring is made of thin aluminum belts, and the multiple thin aluminum belts are spaced to effectively reduce the alternating current loss.

[0020] The wire slot arranged on the surface of the framework can improve the positioning accuracy of the superconducting cable and ensure the stability of the cable during the pulse operation of the magnet. BRIEF DESCRIPTION OF DRAWINGS

[0021] The above and other objects, features and advantages of the present application will become more apparent from the following description of embodiments of the present application, taken in conjunction with the accompanying drawings, in which:

[0022] Figure 1 The overall structure of the liquid-helium-free superconducting magnet for the rotating gantry is schematically shown.

[0023] Figure 2 The axial view of the cooling assembly of the superconducting magnet is schematically shown.

[0024] Figure 3 The overall structure of the superconducting coil framework is schematically shown.

[0025] Figure 4 The cross-sectional view of the liquid-helium-free superconducting magnet is schematically shown.

[0026] Figure 5 The cross-sectional view of the superconducting coil framework and the coil assembly is schematically shown. DETAILED DESCRIPTION

[0027] To make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to specific embodiments and drawings. Obviously, the described embodiments are some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0028] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "includes" and tautological expressions thereof, such as "including," "includes," "include," "contains," "containing," "has," "having," "has," "having," "comprising," "comprise," and / or the like, are open-ended terms that specifically mean "comprises at least the recited elements or steps," but do not exclude other elements or steps.

[0029] In this application, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting", "fixing" and the like should be understood in a broad sense, for example, it can be fixed connection, or detachable connection, or integrated; it can be mechanical connection, or electrical connection or can communicate with each other; it can be direct connection, or indirect connection through intermediate medium, it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0030] In the description of the present application, it should be understood that the terms "longitudinal", "length", "circumferential", "front", "back", "left", "right", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the subsystems or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0031] Throughout the drawings, the same elements are denoted by the same or similar reference numerals. When it may cause confusion in understanding the present application, the conventional structure or configuration will be omitted. And the shape, size, positional relationship of each component in the drawing does not reflect the true size, proportion and actual positional relationship. In addition, in the claims, any reference symbol located between parentheses should not be construed as a limitation on the claims.

[0032] Similarly, in order to simplify the present application and help understand one or more of the various disclosed aspects, in the above description of the exemplary embodiments of the present application, various features of the present application are sometimes grouped together in a single embodiment, figure or description thereof. The description of the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In the specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0033] In addition, the terms "first", "second", etc. are used only for descriptive purposes and are not to be construed as indicating or implying relative importance or an indicated number of the technical features. Therefore, the technical features defined with "first", "second", etc. can explicitly or implicitly include one or more of the technical features. In the description of the present application, the meaning of "a plurality of" is at least two, for example, two, three, etc., unless otherwise explicitly specified.

[0034] In order to realize the application scene requirement of miniaturization and light weight of the rotating gantry, the embodiment of the present disclosure provides a new liquid-helium-free superconducting magnet, which reduces the weight of the superconducting magnet and the alternating current loss as much as possible and improves the cooling efficiency under the condition of meeting the pulse operation of the magnet.

[0035] Figure 1 The overall structure diagram of the liquid-helium-free superconducting magnet for the rotating gantry provided by the embodiment of the present application is schematically shown. Figure 2 The axonometric view of the superconducting magnet cold guide assembly provided by the embodiment of the present application is schematically shown.

[0036] As shown in Figure 1 and Figure 2 , the main structure of the liquid-helium-free superconducting magnet of the rotating gantry includes a superconducting coil framework 1, a superconducting coil assembly 2, a cold guide assembly 3, a two-stage cold guide conversion plate 4, a cold guide copper braid 5, a refrigerator 6, and a thermostat 7.

[0037] The superconducting coil framework 1 is a circular ring structure and is made of non-metallic G10 material.

[0038] The superconducting coil assembly 2 is wound on the surface of the superconducting coil framework 1.

[0039] The cold guide assembly 3 is a ring-shaped conduction cooling structure and is nested with the superconducting coil framework 1 and is configured to transfer cold energy to the surface of the superconducting coil assembly 2 to cool the superconducting coil assembly 2.

[0040] One end of the cold guide copper braid 5 is connected with the cold guide assembly 3, the other end of the cold guide copper braid 5 is connected with the two-stage cold guide conversion plate 4, and the refrigerator 6 is connected with the two-stage cold guide conversion plate 4.

[0041] The cold energy is transferred to the two-stage cold guide conversion plate 4 through the cold head of the refrigerator 6 and then is transferred to the cold guide assembly 3 through the cold guide copper braid 5.

[0042] Figure 3 The overall structure diagram of the superconducting coil framework provided by the embodiment of the present application is schematically shown, Figure 4 The cross-sectional view of the liquid-helium-free superconducting magnet provided by the embodiment of the present application is schematically shown.

[0043] Further, as shown in Figure 3 and Figure 4As shown, the superconducting coil former 1 comprises: a superconducting quadrupole coil G10 former 1-1, a superconducting dipole coil G10 former 1-2, and a former connecting end plate 1-3. The superconducting quadrupole coil G10 former 1-1 and the superconducting dipole coil G10 former 1-2 are nested and fixedly connected by the former connecting end plate 1-3 at both sides of the end portion.

[0044] Since the superconducting coil former 1 is made of non-metallic G10 material, the weight of the former is light, and the non-metallic former does not generate eddy current during pulse operation, which can greatly reduce the total AC loss of the magnet. The weight reduction of the former reduces the weight of the entire superconducting magnet, which can meet the lightweight use requirement of the rotating gantry.

[0045] Figure 5 The cross-sectional view of the superconducting coil former and the coil assembly provided by the embodiment of the application is schematically shown.

[0046] Further, as shown, Figure 5 The outer surface of the superconducting coil former 1 is provided with a wire slot, and the superconducting coil assembly 2 is formed after the superconducting cable is wound along the wire slot and then epoxy cured.

[0047] Specifically, the wire slot is machined on the outer surface of the superconducting coil former 1 by numerical control, and the superconducting cable is precisely embedded in the wire slot by the constraint of the wire slot, which can improve the positioning accuracy of the superconducting cable. The superconducting cable completes the winding of the superconducting coil assembly 2 along the wire slot path on the surface of the superconducting coil former 1, and is fixed in the wire slot after epoxy curing, which can ensure that the superconducting cable does not move during the pulse operation of the superconducting magnet.

[0048] Referring to Figure 2 , the cold conducting assembly 3 comprises: an end cold conducting plate 3-1, an axial cold conducting strip 3-2, and a radial cold conducting ring 3-3.

[0049] The axial cold conducting strip 3-2 is distributed along the axial direction of the superconducting coil former 1 to form an axial cooling channel, and the end cold conducting plate 3-1 is distributed at a predetermined angle on the end portion of the superconducting coil former 1 and is integrally connected with the axial cold conducting strip 3-2. The radial cold conducting ring 3-3 is wound along the radial direction of the superconducting coil former 1 and is spaced apart along the axial direction to form a radial cooling channel, and the axial cold conducting strip 3-2 and the radial cold conducting ring 3-3 are connected at the intersection position.

[0050] In some embodiments, the axial cold conducting strip 3-2 is composed of a thin copper strip, and the radial cold conducting ring 3-3 is composed of a plurality of thin aluminum strips. The annular cooling channel is constructed by the plurality of thin aluminum strips, and the spaced distribution of the plurality of thin aluminum strips can effectively reduce the AC loss.

[0051] Further, the cold conducting assembly 3 further comprises a middle cold conducting plate 3-4, which is connected with the radial cold conducting ring 3-3 through the superconducting coil former 1, and the middle cold conducting plate 3-4 is composed of multiple layers of thin copper strips stacked together, which can effectively reduce the AC loss.

[0052] The end cold conducting plate 3-1 and the middle cold conducting plate 3-4 are connected with the secondary cold head of the low-temperature refrigerator 6 through the flexible cold conducting copper braid 5 to form a cooling path.

[0053] The axial cold conducting strip 3-2 and the radial cold conducting ring 3-3 are configured to adjust the eddy current loss of the liquid-helium-free superconducting magnet by adjusting the size parameters. For example, the eddy current can be reduced by optimizing the size parameters (width, thickness) of the axial cold conducting strip 3-2 and the radial cold conducting ring 3-3, and the overall loss can be controlled within an acceptable range.

[0054] In some embodiments, the refrigerator 6 is fixed on the thermostat 7 maintenance tower, the cold head of the refrigerator 6 is connected with the secondary cold conducting conversion plate 4, one end of the cold conducting copper braid 5 is connected with the secondary cold conducting conversion plate 4, and the other end is connected with the end cold conducting strip 3-1 and the middle cold conducting plate 3-4. The cold conducting path is as follows: the cold quantity is transmitted from the cold head of the refrigerator 6 to the secondary cold conducting conversion plate 4, then transmitted from the secondary cold conducting conversion plate 4 to the end cold conducting strip 3-1 and the middle cold conducting plate 3-4 through the cold conducting copper braid 5, and finally transmitted from the end cold conducting strip 3-1 and the middle cold conducting plate 3-4 to the surface of the magnet coil through the axial cold conducting strip 3-2 and the radial cold conducting ring 3-3, so as to complete the transmission and cooling of the cold quantity.

[0055] In summary, the liquid-helium-free superconducting magnet for a rotating gantry provided by the embodiments of the present disclosure adopts thin aluminum strips to construct radial cooling channels, thin copper strips to construct axial cooling channels, and a conduction cooling structure of the main cooling path arranged at the end of the magnet and the pole head to realize 1 liquid-helium-free conduction cooling while ensuring the stability of the rotating gantry superconducting magnet during rotation. The coil former is made of G10 material, which reduces the weight of the superconducting magnet and ensures the lightweight of the overall structure of the rotating gantry. The G10 coil former greatly reduces the AC loss of the magnet during pulse operation. The method of optimizing the size parameters reduces the eddy current of various cooling components, so that the overall eddy current loss is controlled within an acceptable range. The design of the former wire slot can improve the positioning accuracy of the superconducting cable, ensure the magnetic field accuracy and the stability of the cable during the pulse operation of the magnet.

[0056] The specific embodiments described above further illustrate the objects, technical solutions and advantages of the present disclosure. It should be understood that the above description is only a specific embodiment of the present disclosure and is not intended to limit the present disclosure. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

1. A liquid-helium-free superconducting magnet for a rotating gantry, characterized by, include: The superconducting coil frame (1) is a ring-shaped structure made of non-metallic G10 material; The superconducting coil skeleton (1) includes: a superconducting quadrupole coil G10 skeleton (1-1), a superconducting diode coil G10 skeleton (1-2), and a skeleton connecting end plate (1-3); wherein, the superconducting quadrupole coil G10 skeleton (1-1) and the superconducting diode coil G10 skeleton (1-2) are nested together and then fixedly connected at both ends by the skeleton connecting end plate (1-3); A superconducting coil assembly (2) is wound on the surface of the superconducting coil skeleton (1); The cooling component (3) is a ring-shaped conductive cooling structure nested with the superconducting coil skeleton (1) and configured to transfer cold energy to the surface of the superconducting coil assembly (2) to cool the superconducting coil assembly (2). The cooling component (3) includes: an end cooling plate (3-1), an axial cooling strip (3-2), a radial cooling ring (3-3), and a central cooling plate (3-4). The axial cooling strip (3-2) is distributed along the axial direction of the superconducting coil skeleton (1) to form an axial cooling channel, and the end cooling plates (3-1) are distributed at a predetermined angle on the surface of the superconducting coil skeleton (1). The end of the superconducting coil skeleton (1) is integrated with the axial cooling strip (3-2). The radial cooling ring (3-3) is wound radially along the superconducting coil skeleton (1) and spaced axially to form a radial cooling channel. The axial cooling strip (3-2) and the radial cooling ring (3-3) are attached and connected at the intersection. The middle cooling plate (3-4) passes through the superconducting coil skeleton (1) and is attached and connected to the radial cooling ring (3-3). The axial cooling strip (3-2) is made of thin copper strip, and the radial cooling ring (3-3) is made of multiple layers of thin aluminum strip. A cooling-conducting copper braided strip (5) is connected at one end to the cooling-conducting assembly (3); The secondary cooling conversion plate (4) is connected to the other end of the cooling copper braided strip (5); The refrigeration unit (6) is connected to the secondary cooling conversion plate (4); The cold energy is transferred to the secondary heat transfer plate (4) through the cold head of the refrigerator (6), and then to the heat transfer assembly (3) through the heat transfer copper braid (5).

2. The liquid-helium-free superconducting magnet for a rotating gantry of claim 1, wherein, The outer surface of the superconducting coil skeleton (1) is provided with a wire groove, and the superconducting coil assembly (2) is formed by winding a superconducting cable along the wire groove and then curing it with epoxy.

3. The liquid-helium-free superconducting magnet for a rotating gantry of claim 1, wherein, The central cooling plate (3-4) is composed of multiple layers of thin copper strips stacked together.

4. The liquid-helium-free superconducting magnet for a rotating gantry of claim 1, wherein, The axial cooling belt (3-2) and the radial cooling ring (3-3) are configured to adjust the eddy current loss of the liquid helium-free superconducting magnet by adjusting the size parameters.

5. The liquid-helium-free superconducting magnet for a rotating gantry of claim 1, wherein, One end of the cooling-conducting copper braided strip (5) is connected to the end cooling-conducting plate (3-1) and the middle cooling-conducting plate (3-4).

6. The liquid-helium-free superconducting magnet for a rotating gantry of claim 1, wherein, The liquid helium-free superconducting magnet also includes: The thermostat (7) is fixed on the maintenance tower of the thermostat (7).

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