A superconducting magnet system for a conduction-cooled cyclotron

Abstract

The present application relates to superconducting magnet conduction cooling technical field, disclose a kind of for conduction cooling revolving accelerator's superconducting magnet system, including conduction cooling structure, superconducting magnet, adjusting structure, protection system.Conduction cooling structure includes cryostat, refrigerator, cold lead, cold plate.Cold lead, cold plate are connected with refrigerator and coil, and the cryostat provides the vacuum low-temperature environment required for the work of superconducting magnet;Superconducting magnet includes superconducting coil, framework and binding tape, superconducting magnet is placed in cryostat, and superconducting coil is fixed on the framework by binding tape;Adjusting structure is connected with coil framework, for adjusting the position of superconducting magnet.The superconducting magnet system of the present application discards the traditional liquid helium immersion refrigeration mode, and uses refrigerator to carry out conduction cooling refrigeration, compared with traditional design, discards valve box structure, structure is simpler, and the cost of low-temperature liquid medium is saved, and the cost of superconducting magnet system is reduced.

Description

Technical Field

[0001] This invention relates to the field of superconducting magnet conduction cooling technology, and more specifically to a superconducting magnet system for conduction cooling of a cyclotron accelerator. Background Technology

[0002] Superconducting magnets are often unavoidable in cyclotrons. However, the temperature of superconducting magnets must be kept below the critical temperature during operation. Existing superconducting magnets used in cyclotrons are cooled by liquid helium. This usually requires the operation and maintenance of traditional structures such as liquid helium valve boxes, which results in high operation and maintenance costs. Furthermore, liquid helium is scarce and there is insufficient safety redundancy.

[0003] Therefore, there is an urgent need for a method that can eliminate dependence on liquid helium supply, greatly reduce operation and maintenance costs, abandon traditional structures such as valve boxes, be smaller in size than liquid helium refrigeration methods, have a simpler structure, and solve the problems of liquid helium scarcity and safety redundancy, thereby improving the reliability of superconducting magnets and reducing operation and maintenance load. Summary of the Invention

[0004] This invention provides a superconducting magnet system for conductive cooling cyclotrons to address the problems of high operation and maintenance costs, large space occupation, and insufficient safety redundancy due to the scarcity of liquid helium.

[0005] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0006] In a first aspect, a superconducting magnet system for a conductively cooled cyclotron accelerator includes a conductive cooling structure, a transition joint, binding straps, a Dewar breaker, and a superconducting magnet disposed within the conductive cooling structure. The superconducting magnet includes a superconducting coil disposed within the conductive cooling structure and a frame disposed within the conductive cooling structure. Two layers of binding straps are wound around the outside of the superconducting coil, and the coil is fixed to the frame by the binding straps. The system also includes:

[0007] The adjustment structure, located on the outside of the conductive cooling structure and connected to the frame, includes: a tie rod, of which eight are axially symmetrically arranged on the upper and lower surfaces of the conductive cooling structure, and the other four are radially arranged on the circumferential side of the conductive cooling structure;

[0008] Each radially arranged tie rod and one axially arranged tie rod above and below it are in the same plane, which is called a tie rod group, and the planes in which each tie rod group is located are perpendicular to each other;

[0009] The cryogenic system is uniformly arranged axially and radially throughout the conductive cooling structure. It includes a cooling conductor located outside the conductive cooling structure and a cooling delivery component that connects to the superconducting coil through the conductive cooling structure. The cooling delivery component is connected to the cooling conductor to eliminate the need for liquid helium cooling while ensuring the cooling effect on the superconducting magnet, thus simplifying the cooling structure.

[0010] The cooling component includes a refrigerator and a cryostat. There are six refrigerators, with three refrigerators located above and below the conductive cooling structure. The refrigerators form a 45-degree angle with the plane where the tie rod assembly is located, and divide the superconducting magnet into four 90-degree sector regions along the circumference. Four of the refrigerators are symmetrically distributed vertically, and the other two are diagonally distributed to ensure uniform temperature distribution of the superconducting magnet.

[0011] Furthermore, a cold screen is provided inside the conductive cooling structure, and the cold screen is located on the side of the superconducting magnet close to the Dewar. The Dewar and the cold screen form a first vacuum cavity, and the cold screen and the surface of the superconducting magnet form a second vacuum cavity.

[0012] Furthermore, a cooling plate is provided on the side of the superconducting coil near the cold shield, the cooling plate is in contact with the superconducting coil, and a cooling strip is wrapped around the outside of the superconducting coil and the binding strap;

[0013] A cold strip pressure plate is provided on the side of the superconducting coil away from the cold screen;

[0014] The cooling strip is fixed to the cooling plate.

[0015] Furthermore, the cooling component includes:

[0016] Low-temperature thermostat, with a through-conductive cooling structure;

[0017] The refrigeration unit is installed at the end of the low-temperature thermostat that is away from the conductive cooling structure.

[0018] The first-stage cold head is connected to the output end of the refrigeration unit and is located inside the low-temperature thermostat;

[0019] The secondary cold head is connected to the end of the primary cold head.

[0020] Furthermore, the cooling component includes:

[0021] The heat transfer aluminum strip is set on the outside of the secondary cold head and the binding strap, and is fixedly connected to the outer surface of the cold screen;

[0022] Copper thermal connection, with the ends of the heat transfer aluminum strips installed;

[0023] The copper thermal connection, which connects to the heat transfer aluminum strip disposed on the outside of the secondary cold head, is located on the outside of the primary cold head;

[0024] The connecting parts are located within the conductive cooling structure and are connected to the secondary cold head.

[0025] Furthermore, the connecting component includes:

[0026] The secondary guide block is connected to the end of the secondary cold head that is furthest from the primary cold head.

[0027] The secondary connector is attached to the side of the secondary guide block furthest from the secondary cold head.

[0028] The cooling plate is located at the end of the secondary connector away from the secondary conductor block, and the cooling plate is in contact with the superconducting coil.

[0029] Furthermore, vacuum pumps and current leads are respectively installed on opposite sides of the other two refrigerators. The vacuum pump is installed above the conductive cooling structure to extract air from the inside of the superconducting magnet. The current lead is located below the conductive cooling structure and is electrically connected to the superconducting coil. The current lead is divided into a high-temperature end and a low-temperature end, which are connected to the high-temperature end through a superconducting connector. A heat sink is installed above the low-temperature end lead. Insulation is installed on the outside of the heat sink. A heat sink cooling strip is installed on the outside of the heat sink and the insulation. The heat sink cooling strip extends from the cold shield to wrap the heat sink for cooling.

[0030] The low-temperature end of the current lead is welded to the cold shield. A low-temperature cavity is provided on the outside of the low-temperature end, and the low-temperature cavity is located outside the heat sink cooling strip and is connected to the second vacuum cavity. A container is provided on the outside of the high-temperature end of the current lead, and the container is located outside the low-temperature cavity and is welded to the Dewar. The container is connected to the first vacuum cavity.

[0031] Furthermore, the pull rod includes:

[0032] The racetrack-shaped tie rods are in sets of two, and each set of racetrack-shaped tie rods is connected to a copper thermal connector located on the outside of the binding strap via a transition joint;

[0033] Adjust the nut and connect it to the end of the racetrack-shaped tie rod away from the strapping via the transition joint;

[0034] The racetrack-shaped tie rod, transition joint, and copper thermal connection and heat transfer aluminum strip located outside the binding strap are provided with a protective shell, and the protective shell is installed through the conductive cooling structure.

[0035] Furthermore, a protection system is provided within the conductive cooling structure, the protection system comprising:

[0036] There are two rectangular grooves, one on the inner surface of the skeleton and the other on the middle plane.

[0037] A plurality of terminal blocks are fixed in a linear array within one of the slots;

[0038] A diode array, comprising eight diodes, is fixed within another slot via a clamping plate;

[0039] A voltage divider resistor plate is disposed in another of the aforementioned slots and is matched with the diode group.

[0040] Furthermore, each of the diode groups is connected in parallel with one-eighth of a superconducting coil for quench protection;

[0041] The diode group includes:

[0042] There are two diodes connected in parallel.

[0043] The above-described solution of the present invention has at least the following beneficial effects:

[0044] By setting up a cryogenic system, the traditional liquid helium immersion cooling structure is abandoned. Instead, six cryogenic units are set at a 45-degree angle to the plane where the tie rod assembly is located, and the superconducting magnet is divided into four 90-degree sector regions along the circumference. Four cryogenic units are symmetrically distributed vertically, and the other two are diagonally distributed to ensure uniform temperature distribution of the superconducting magnet. Compared with the traditional design, the valve box structure is eliminated, the structure is simpler, and the cost of cryogenic liquid medium is saved, reducing the cost of the superconducting magnet system and improving the reliability of the superconducting magnet. Attached Figure Description

[0045] Figure 1 This is an overall perspective view of the superconducting magnet system provided in an embodiment of the present invention;

[0046] Figure 2 A three-dimensional structural diagram of the combination of cooling belt, cryostat and vacuum pump provided in an embodiment of the present invention;

[0047] Figure 3 This is a cross-sectional view of the container and a three-dimensional structural diagram of the combination of the binding straps and the refrigeration unit provided in an embodiment of the present invention;

[0048] Figure 4 A cross-sectional plan view of the refrigerator, secondary guide block and secondary connector assembly provided in an embodiment of the present invention;

[0049] Figure 5 A three-dimensional structural diagram of the skeleton and conductive cooling structure combination provided in an embodiment of the present invention;

[0050] Figure 6 A perspective view of the combination of the cold guide plate, the cold belt pressure plate, and the conductive cooling structure provided in an embodiment of the present invention;

[0051] Figure 7 A schematic diagram of the planar structure of the transition joint, adjusting nut, and racetrack-shaped tie rod assembly provided in an embodiment of the present invention;

[0052] Figure 8 This is a planar sectional view of a superconducting magnet system provided in an embodiment of the present invention;

[0053] Figure 9 This is a plan view of the superconducting magnet system provided in an embodiment of the present invention;

[0054] Figure 10 This is a top cross-sectional view of a superconducting magnet system provided in an embodiment of the present invention.

[0055] Explanation of reference numerals in the attached figures:

[0056] In the diagram: 101, Conductive cooling structure; 102, Superconducting magnet; 103, Adjustment structure; 104, Protection system; 1001, Superconducting coil; 1002, Frame; 1003, Binding strap; 201, Refrigeration unit; 202, Low-temperature thermostat; 203, Cooling strip; 204, Cooling plate; 301, Dewar; 302, Cold shield; 303, Current lead; 304, Vacuum pump; 2001, First-stage cold head; 2002, Second-stage cold head; 20 03. Copper thermal connector; 2004. Heat transfer aluminum strip; 2005. Secondary conductor block; 2006. Secondary connector; 2007. Cold strip pressure plate; 3001. Adjusting nut; 3002. Transition joint; 3003. Racetrack-shaped tie rod; 3031. Heat sink; 3032. Heat sink cooling strip; 3033. Insulation; 3034. Low temperature cavity; 3035. Container; 4001. Voltage divider resistor plate; 4002. Diode group; 4003. Terminal cup. Detailed Implementation

[0057] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0058] like Figures 1 to 10 As shown, an embodiment of the present invention provides a superconducting magnet system for a conductively cooled cyclotron accelerator, including a conductive cooling structure 101, a transition joint 3002, binding straps 1003, and a Dewar 301 disposed inside the conductive cooling structure 101, and a superconducting magnet 102 disposed between the conductive cooling structure 101 and the Dewar 301. The superconducting magnet 102 includes a superconducting coil 1001 disposed within the conductive cooling structure 101 and a frame 1002 disposed within the conductive cooling structure 101. Two layers of binding straps 1003 are wound around the outside of the superconducting coil 1001 and it is fixed to the frame 1002 by the binding straps 1003. The system also includes:

[0059] The cryogenic system is uniformly arranged axially and radially through the conductive cooling structure 101. It includes a cooling conductor disposed outside the conductive cooling structure 101 and a cooling delivery component that is thermally connected to the superconducting coil 1001 through the conductive cooling structure 101. The cooling delivery component is connected to the cooling conductor to eliminate the need for liquid helium cooling while ensuring the cooling effect on the superconducting magnet 102, thus simplifying the cooling structure.

[0060] The adjustment structure 103 is located on the outside of the conductive cooling structure 101 and is connected to the frame 1002. It includes: a tie rod with twelve rods, eight of which are axially symmetrically arranged on the upper and lower surfaces of the conductive cooling structure 101, and the other four are radially arranged on the circumferential side of the conductive cooling structure 101.

[0061] Each radially arranged tie rod and one axially arranged tie rod above and below it are in the same plane, which is called a tie rod group, and the planes in which each tie rod group is located are perpendicular to each other;

[0062] The cooling components include a refrigerator 201 and a cryostat 202. There are six refrigerators 201, with three refrigerators 201 arranged above and below the conductive cooling structure 101. The refrigerators 201 form a 45-degree angle with the plane where the tie rod assembly is located, and divide the superconducting magnet 102 into four 90-degree sector regions along the circumference. Four refrigerators 201 are symmetrically distributed vertically, and the other two refrigerators 201 are diagonally distributed to ensure uniform temperature distribution of the superconducting magnet 102.

[0063] Specifically, the conductive cooling structure 101 provides protection and support for its internal components, provides stable support for the Dewar 301, and works with the Dewar 301 to provide placement space and support for the superconducting magnet 102. The Dewar 301, together with the conductive cooling structure 101, can construct a highly efficient cryogenic insulation container 3035. The skeleton 1002, together with the binding straps 1003, can stably support the superconducting magnet 102 under the support of the conductive cooling structure 101 and the Dewar 301. The superconducting coil 1001 can generate magnetic force in the superconducting magnet 102 after being energized. The refrigerator 201 can actively cool after starting, providing continuous cooling for the extremely low temperature environment required for the superconducting state.

[0064] In practical applications, the cryostat 201 is connected to the high-magnetic-field superconducting magnet 102 and provides the necessary low-temperature environment to maintain superconducting stability. The cooling strip 203 and cooling plate 204 are connected to the cryostat 201 and wrap around the superconducting coil 1001, establishing an efficient thermal path to enhance the transfer of cold energy from the cryostat 201. Combined with multi-layer insulation and a high-vacuum environment, this system can precisely control the magnet temperature, effectively suppress thermal disturbances, and the adjustment structure 103 can adjust the position of the superconducting magnet 102 under external force.

[0065] In a preferred embodiment of the present invention, a cold screen 302 is provided in the conductive cooling structure 101, and the cold screen 302 is located on the side of the superconducting magnet 102 close to the Dewar 301. The Dewar 301 and the cold screen 302 form a first vacuum cavity, and the cold screen 302 and the surface of the superconducting magnet form a second vacuum cavity.

[0066] Specifically, the outer temperature of Dewar 301 is room temperature, the outer temperature of cold screen 302 is 60K, the surface temperature of superconducting magnet 102 is 4.2K, cold screen 302 can conduct heat, and the first vacuum chamber and the second vacuum chamber can play a role in heat insulation to maintain a low temperature environment.

[0067] A cooling plate 204 is provided on the side of the superconducting coil 1001 that is close to the cold screen 302. The cooling plate 204 is attached to the superconducting coil 1001. The superconducting coil 1001 and the binding strap 1003 are wrapped with a cooling strip 203.

[0068] A cold strip pressure plate 2007 is provided on the side of the superconducting coil 1001 away from the cold shield 302;

[0069] The cooling guide strip 203 is fixed on the cooling guide plate 204.

[0070] In practical application, the cold energy from the cold screen 302 is first transferred to the cold-conducting plate 204, and then, through the fully fitted contact surface, the heat conduction area is maximized, reducing contact thermal resistance, and the energy is transferred to the superconducting coil 1001. This solves the problem of low cold energy transfer efficiency caused by the lack of direct contact between the cold source and the superconducting coil 1001. The cold-conducting plate 204 is typically sheet-shaped or ring-shaped, covering the heat dissipation surface of the superconducting coil 1001 near the cold screen 302. This allows the cold energy to be evenly distributed to different areas of the superconducting coil 1001, preventing hot spots from appearing in certain areas of the superconducting coil 1001 due to insufficient cooling. The binding strap 1003 is made of aluminum, which has good thermal conductivity. It is wrapped around the outside of the superconducting coil 1001 and serves as the first layer of structural constraint for the superconducting coil 1001, and can also counteract... The radial tension of the superconducting coil 1001 during excitation is due to the outward expansion force generated by the interaction of the magnetic field when a large current flows through it. Two layers of binding straps 1003, through pre-tight winding, tightly bind the superconducting coil 1001, preventing it from loosening, deforming, or the wires from shifting, thus ensuring magnetic field uniformity. The cold-conducting plate 204 only covers the side of the superconducting coil 1001 closest to the cold shield 302, while the cold-conducting straps 203, by completely wrapping the coil, can reach the sides of the superconducting coil 1001, the side away from the cold shield 302, and other areas not covered by the cold-conducting plate 204, transferring cold energy to the entire superconducting coil 1001. This solves the problem of localized temperature differences caused by incomplete coverage by a single cold-conducting plate 204. The wrapping structure can be combined with the binding straps 1003. In synergy, the radial constraint on the superconducting coil 1001 is further enhanced. The cooling tape 203 itself has a certain rigidity, and after wrapping, it can assist the binding tape 1003 in pressing the superconducting coil 1001 tightly, reducing the vibration or displacement of the superconducting coil 1001 during excitation. If the heat leakage in a certain area of ​​the superconducting coil 1001 is high, such as on the side far from the cold screen 302, the cooling tape 203 can use its high thermal conductivity to guide the cold energy of the cooling plate 204 to that area, reducing the temperature difference across the entire superconducting coil 1001. The cooling tape pressure plate 2007 can fix the cooling tape 203 to the cooling plate 204. Through the pressure of the cooling tape pressure plate 2007, the cooling tape 203 is tightly pressed onto the cooling plate 204, or onto the fixed structure extending from the cooling plate 204, ensuring... There is no gap between the cooling strip 203 and the cooling plate 204. Gaps would create contact thermal resistance, hindering the transfer of cold energy. The pressure of the pressure plate minimizes this contact thermal resistance, ensuring that the cooling strip 203 can efficiently absorb cold energy from the cooling plate 204. Furthermore, the pressure plate 2007 tightly secures the multi-layered structure of the cooling plate 204, coil, binding strap 1003, and cooling strip 203, preventing relative displacement between layers due to vibration. This avoids contact failure or wear of the coil insulation layer 3033. Since the side of the superconducting coil 1001 furthest from the cold shield 302 lacks cold source support, the pressure plate 2007 serves as a mechanical support point on that side, balancing the forces on both sides of the superconducting coil 1001 and preventing bending deformation due to unilateral force.The cold shield 302 is a cryogenic shielding component directly cooled by the cryo-cooler 201. Located inside the Dewar 301, it shields the superconducting coil 1001 from external radiant heat and provides a stable cold source for the cold-conducting plate 204. Through direct contact with the cold-conducting plate 204, the cold shield 302 transfers the cooling energy generated by the cryo-cooler 201 to the cold-conducting plate 204, which, along with the cold-conducting strip 203, distributes the cooling energy to the superconducting coil 1001.

[0071] As a preferred embodiment of the present invention, the adjustment structure 103 is disposed on the outside of the conductive cooling structure 101 and connected to the frame 1002, and includes: a tie rod having twelve rods, of which eight rods are axially symmetrically disposed on the upper and lower surfaces of the conductive cooling structure 101, and the other four rods are radially disposed on the circumferential side surface of the conductive cooling structure 101.

[0072] Each radially arranged tie rod and one axially arranged tie rod above and below it are in the same plane, which is called a tie rod group, and the planes in which each tie rod group is located are perpendicular to each other;

[0073] The cooling components include a refrigerator 201 and a cryostat 202. There are six refrigerators 201, with three refrigerators 201 arranged above and below the conductive cooling structure 101. The refrigerators 201 form a 45-degree angle with the plane where the tie rod assembly is located, and divide the superconducting magnet 102 into four 90-degree sector regions along the circumference. Four refrigerators 201 are symmetrically distributed vertically, and the other two refrigerators 201 are diagonally distributed to ensure uniform temperature distribution of the superconducting magnet 102.

[0074] Specifically, the tie rod assembly is typically distributed radially or axially along the magnet. If the chiller 201 is arranged along the plane of the tie rod, the cold head will be blocked by the tie rod, resulting in a cold energy blind zone on the magnet surface. The temperature of the area not covered by the chiller 201 will rise. At the same time, physical collisions between the tie rod and the chiller 201 can damage components or cause poor contact of the cold head, reducing the efficiency of cold energy transfer. The 45-degree angle setting allows the chiller 201 to be installed at a different position than the tie rod assembly, avoiding mechanical collisions and ensuring the stable fixation of the chiller 201. The gaps between the tie rods in the non-tip rod plane area are covered by the chiller 201 arranged at a 45-degree angle, making the cold energy distribution on the upper and lower surfaces of the superconducting magnet 102 more continuous, without localized hot spots that cannot be removed due to heat leakage. 2. Most of them are ring structures. The heat leakage in the circumferential direction may be uneven due to the difference in the position of the support point and the interface of the current lead 303 (for example, more heat leakage near the current lead 303). If the refrigerators 201 are randomly arranged, it is easy to cause insufficient cooling in a certain circumferential area and temperature deviation. The superconducting magnet 102 is divided into independent 90-degree sector areas for temperature control. The temperature of each area can be adjusted individually by the refrigerators 201 in the area, avoiding the problem of all cooling and heating. It can be ensured that there is at least one refrigerator 201 in each sector area. Even if the heat leakage in a certain area suddenly increases, the refrigerators 201 in that area can quickly replenish the cooling capacity to prevent the temperature from exceeding the standard, thus ensuring the temperature uniformity of the entire superconducting magnet 102 in space.

[0075] Six chillers 201 can achieve symmetrical main cooling and local supplementary cooling, ensuring sufficient cooling capacity while avoiding redundancy and waste. Too many chillers 201 would increase energy consumption, while too few would be unable to cope with heat leakage fluctuations. Four chillers 201, symmetrically distributed vertically, cover the main heat dissipation area of ​​the superconducting magnet 102. The symmetrical layout balances the cooling capacity of the upper and lower surfaces, preventing thermal stress caused by temperature differences between the upper and lower surfaces of the magnet. The other two chillers 201 can specifically supplement local heat leakage, such as the current lead 303 in the transition zone from room temperature to low temperature, where heat leakage is higher than in other areas. The other two chillers 201 can specifically remove this extra heat to prevent the area from becoming a temperature hotspot.

[0076] Cooling components include:

[0077] The low-temperature thermostat 202 is installed through the conductive cooling structure 101;

[0078] The refrigeration unit 201 is installed at the end of the low-temperature thermostat 202 that is away from the conductive cooling structure 101;

[0079] The first-stage cold head 2001 is connected to the output end of the refrigeration unit 201 and is located inside the low-temperature thermostat 202;

[0080] The secondary cold head 2002 is connected to the end of the primary cold head 2001.

[0081] Specifically, the low-temperature thermostat 202 provides support for the refrigerator 201 and insulates against heat, protecting the primary cold head 2001 and the secondary cold head 2002. After the refrigerator 201 starts, it can transfer the cooling capacity to the primary cold head 2001, which in turn can transfer the cooling capacity to the secondary cold head 2002 and the copper thermal connector 2003. The secondary cold head 2002 can then transfer the cooling capacity to the heat transfer aluminum strip 2004.

[0082] Refrigerated parts include:

[0083] The heat transfer aluminum strip 2004 is set on the outside of the secondary cold head 2002 and the binding strap 1003, and is fixedly connected to the outer surface of the cold screen 302.

[0084] Copper thermal connector 2003, with the end of heat transfer aluminum strip 2004 provided;

[0085] The copper thermal connection 2003, which is connected to the heat transfer aluminum strip 2004 set on the outside of the secondary cold head 2002, is located on the outside of the primary cold head 2001.

[0086] The connecting parts are located within the conductive cooling structure 101 and are connected to the secondary cold head 2002.

[0087] Specifically, the heat transfer aluminum strip 2004 can transfer the cold energy to the cold screen 302, while the secondary cold head 2002 can transfer the cold energy to the secondary conductor block 2005.

[0088] The connecting parts include:

[0089] The secondary guide block 2005 is connected to the end of the secondary cold head 2002 that is furthest from the primary cold head 2001;

[0090] The secondary connector 2006 is connected to the side of the secondary guide block 2005 away from the secondary cold head 2002;

[0091] The cooling plate 204 is located at the end of the secondary connector 2006 away from the secondary conductor block 2005, and the cooling plate 204 is in contact with the superconducting coil 1001.

[0092] Specifically, the secondary conductor block 2005 can transfer the cold energy to the secondary connector 2006, and the secondary connector 2006 can transfer the cold energy to the cold-conducting plate 204, so that the cold-conducting plate 204 can cooperate with the cold-conducting strip 203 to distribute the cold energy to the superconducting coil 1001.

[0093] In practical application, the cold energy generated by the primary cold head 2001 of the refrigerator 201 is first conducted to the copper thermal connector 2003, and then transferred to the cold screen 302 through the heat transfer aluminum strip 2004. The cold energy generated by the secondary cold head 2002 of the refrigerator 201 is conducted to the secondary guide block 2005 and the secondary connector 2006, and then transferred to the cold conduction plate 204 before being transferred to the coil. In order to ensure that the coil reaches the superconducting state, the cold energy is also transferred to the cold conduction strip 203 that wraps around the coil. The cold conduction strip 203 transfers the cold energy to the other three surfaces of the coil that are not in contact with the cold conduction plate 204.

[0094] The refrigerator 201 is the source of cooling capacity, replacing the passive cooling capacity storage and conduction function of traditional liquid helium. It continuously generates low-temperature cooling capacity through internal working fluid circulation, and directly contacts the cooling interface of the superconducting magnet 102 through components such as the primary cold head 2001, secondary cold head 2002, heat transfer aluminum strip 2004, copper heat connection 2003, secondary conductor block 2005, and secondary connector 2006. This actively removes the heat generated by the magnet, eliminating the need to store large amounts of liquid helium and avoiding the costs and safety risks of frequent replenishment caused by liquid helium leakage and evaporation. It achieves liquid helium-free operation, and the power of the refrigerator 201 can be adjusted in real time as needed to adjust the cooling effect and improve temperature stability.

[0095] In a preferred embodiment of the present invention, a vacuum pump 304 and a current lead 303 are respectively provided on opposite sides of the other two refrigerators 201. The vacuum pump 304 is installed above the conductive cooling structure 101 to extract air from the inside of the superconducting magnet. The current lead 303 is located below the conductive cooling structure 101 and is electrically connected to the superconducting coil 1001. The current lead 303 is divided into a high-temperature end and a low-temperature end, which are connected by a superconducting connector. A heat sink 3031 is provided above the low-temperature end lead. An insulation 3033 is provided on the outside of the heat sink 3031. A heat sink cooling strip 3032 is provided on the outside of the heat sink 3031 and the insulation 3033. The heat sink cooling strip 3032 is led out from the cold screen 302 to wrap the heat sink 3031 for cooling.

[0096] The low-temperature end of the current lead 303 is welded to the cold shield 302. A low-temperature cavity 3034 is provided on the outside of the low-temperature end. The low-temperature cavity 3034 is located outside the heat sink cooling strip 3032 and is connected to the second vacuum cavity. A container 3035 is provided on the outside of the high-temperature end of the current lead 303. The container 3035 is located outside the low-temperature cavity 3034 and is welded to the Dewar 301. The container 3035 is connected to the first vacuum cavity.

[0097] Specifically, the vacuum pump 304 is used to extract air from inside the superconducting magnet 102 and, by utilizing the characteristics of vacuum insulation, provides the vacuum environment required for the operation of the superconducting magnet 102.

[0098] In practical application, the first-stage cold head 2001 transfers the cooling energy to the heat sink cooling belt 3032 through the cold screen 302. The heat sink cooling belt 3032 then transfers the cooling energy to the heat sink 3031 to control the temperature of the heat sink 3031. The gaps between the cooling belts 203 are filled with epoxy to ensure that there are no gaps inside the superconducting magnet 102, thus ensuring the vacuum degree of the magnet. At the same time, it ensures the mechanical structural integrity of the magnet during operation and matches the thermal contraction at low temperatures.

[0099] The heat sink 3031 actively absorbs heat conducted from the high-temperature end by the current lead, preventing direct heat transfer to the low-temperature end and the superconducting coil 1001. This effectively creates a heat-blocking barrier between the high-temperature and low-temperature ends, reducing heat leakage into the core area of ​​the superconducting magnet 102. The insulation 3033 prevents short circuits between the heat sink 3031 and surrounding components, avoiding current leakage that could affect excitation efficiency. Its low thermal conductivity further blocks the heat absorbed by the heat sink 3031 from diffusing outwards, enhancing the insulation effect. The heat sink cooling strip 3032 acts as a cold energy transfer channel, transferring the low-temperature cooling energy from the cooling shield 302 to the heat sink 3031, actively cooling it. The heat absorbed by the heat sink 3031 is quickly carried away by the cooling strip 3032, maintaining the heat sink 3031 at a consistently low temperature and continuously retaining its heat-blocking capability. To prevent the heat sink 3031 from losing its heat leakage control function due to the increase in temperature caused by heat accumulation, the low-temperature cavity 3034 can provide an independent low-vacuum environment for the low-temperature end of the current lead 303, preventing the low-temperature end from directly contacting the external ambient temperature area through the container 3035, reducing radiative heat transfer and gas conduction. The container 3035 can form a double-layer vacuum barrier between the high-temperature end and the low-temperature cavity, further weakening heat transfer. Welding with the Dewar 301 ensures vacuum sealing performance, preventing external air from seeping in and disrupting the vacuum. At the same time, it fixes the position of the high-temperature end of the current lead, preventing the current lead 303 from being displaced due to the electromagnetic force of the current or equipment vibration, ensuring stable current transmission, ensuring that the superconducting coil 1001 stably receives current in the extremely low temperature and high vacuum environment, maintains the zero-resistance superconducting state, generates a uniform strong magnetic field, and meets the requirements of the cyclotron to bind and accelerate charged particles.

[0100] In a preferred embodiment of the present invention, the pull rod includes:

[0101] The racetrack-shaped tie rod 3003 is in sets of two. Each set of racetrack-shaped tie rods 3003 is connected to the copper thermal connector 2003 located on the outside of the binding strap 1003 via a transition joint 3002.

[0102] Adjusting nut 3001 is connected to the end of racetrack-shaped tie rod 3003 away from the binding strap 1003 via transition joint 3002;

[0103] The racetrack-shaped tie rod 3003, the transition joint 3002, and the copper thermal connection 2003 and the heat transfer aluminum strip 2004 located outside the binding strap 1003 are provided with protective shells, and the protective shells are provided through the conductive cooling structure 101.

[0104] Specifically, the superconducting magnet 102 also includes a superconducting power supply, which is connected to the coil through the current lead 303 to apply current during the excitation and demagnetization stages of the superconducting magnet 102. The first-stage cold head 2001 transfers the cooling energy through the cold screen 302 to the heat transfer aluminum strip 2004 and copper thermal connection 2003 connected to it, and then transfers the cooling energy to the racetrack-shaped tie rod 3003.

[0105] In practical applications, the adjusting nut 3001 is used to adjust the tension or length of the racetrack-shaped tie rod 3003. By rotating the adjusting nut 3001, the supporting force or position of the racetrack-shaped tie rod 3003 on the superconducting coil 1001 can be precisely adjusted, thereby achieving fine adjustment of the magnetic field of the superconducting magnet 102, such as adjusting the first harmonic of the magnetic field of the superconducting coil 1001 to meet the requirements of accelerator operation. The transition joint 3002 serves as a connection and transition. It firmly connects the racetrack-shaped tie rod 3003 to the copper thermal connector 2003, enabling the transmission of force and the conduction of heat between the two, ensuring the stability of the mechanical and thermal performance of the entire system.

[0106] In a preferred embodiment of the present invention, a protection system 104 is provided within the conductive cooling structure 101, and the protection system 104 includes:

[0107] Two rectangular grooves are formed, one on the inner surface and the other on the middle plane of the skeleton 1002.

[0108] The 4003 connector has multiple units, which are fixed in a linear array within one of the slots.

[0109] The diode group 4002, consisting of eight diodes, is fixed in another slot by a clamping plate.

[0110] The voltage divider resistor plate 4001 is disposed in another slot and is matched with the diode group 4002.

[0111] Specifically, the layout of the two rectangular slots not only makes full use of the internal geometric space of the skeleton 1002, but also completes the function of quench protection.

[0112] Each diode group 4002 is connected in parallel with one-eighth of a superconducting coil 1001 for quench protection;

[0113] Diode group 4002 includes:

[0114] There are two diodes connected in parallel.

[0115] In practical applications, the protection system 104 is connected to the superconducting magnet 102, and the superconducting magnet 102 is de-energized and its energy is discharged when it loses quench.

[0116] The rectangular slot provides mounting positions for components such as the junction cup 4003, diode group 4002, and voltage divider resistor plate 4001, allowing these components to be arranged in an orderly manner and ensuring the normal operation of the protection system 104. At the same time, this layout helps to realize the quench protection function. When the superconducting magnet 102 quenches, it can provide a suitable path and space for the current, making it easier for subsequent components to handle the situation. The junction cup 4003 can be conveniently connected to the circuit for connecting the superconducting coil 1001 to the external circuit, facilitating the introduction and extraction of current. The junction box 4003 allows for reliable connection of the superconducting coil 1001 to power supplies, measuring equipment, etc., ensuring the circuit integrity of the entire magnet system and facilitating installation and maintenance. The diode group 4002 acts as a current shunt and voltage limiter when the superconducting magnet 102 fails to quench. When the superconducting coil 1001 fails to quench, the coil resistance increases rapidly, and the terminal voltage rises. At this time, the diode group 4002 conducts, shunting the quench current and preventing the superconducting coil 1001 from being subjected to excessive voltage, thus protecting it from damage. The voltage divider resistor 4001 works in conjunction with the diode group 4002 to further limit the voltage and consume energy when the superconducting magnet 102 fails to quench. The voltage divider resistor 4001 divides the high voltage generated by the failure of the superconducting coil 1001, making the voltage distribution more uniform, while consuming some energy to accelerate the quench process of the magnet and protect the safety of the magnet and other related equipment.

[0117] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A superconducting magnet system for a conductively cooled cyclotron accelerator, comprising a conductive cooling structure, a transition joint, binding straps, a Dewar breaker, and a superconducting magnet disposed within the conductive cooling structure, wherein the superconducting magnet includes a superconducting coil disposed within the conductive cooling structure and a frame disposed within the conductive cooling structure, the superconducting coil being wound with two layers of binding straps on its outer side and fixed to the frame by the binding straps, characterized in that, Also includes: A cold shield is provided inside the conductive cooling structure; An adjustment structure, located outside the conductive cooling structure and connected to the frame, includes: twelve tie rods, eight of which are axially symmetrically arranged on the upper and lower surfaces of the conductive cooling structure, and the other four are radially arranged on the circumferential side of the conductive cooling structure; each radially arranged tie rod and one axially arranged tie rod above and below are in the same plane, forming a tie rod group, and the planes of each tie rod group are perpendicular to each other; The cryogenic system is uniformly arranged axially and radially throughout the conductive cooling structure. It includes a cooling conductor located outside the conductive cooling structure and a cooling delivery component that connects to the superconducting coil through the conductive cooling structure. The cooling delivery component is connected to the cooling conductor to eliminate the need for liquid helium cooling while ensuring the cooling effect on the superconducting magnet, thus simplifying the cooling structure. The cooling component includes a refrigerator and a cryostat. There are six refrigerators, with three refrigerators located above and below the conductive cooling structure. The refrigerators form a 45-degree angle with the plane where the tie rod assembly is located, and divide the superconducting magnet into four 90-degree sector regions along the circumference. Four of the refrigerators are symmetrically distributed vertically, and the other two are diagonally distributed to ensure uniform temperature distribution of the superconducting magnet. A cooling plate is provided on the side of the superconducting coil closest to the cold screen, and the cooling plate is in contact with the superconducting coil. A cooling strip is wrapped around the outside of the superconducting coil and the binding strap. A cooling strip pressure plate is provided on the side of the superconducting coil away from the cold screen. The cooling strip is fixed to the cooling plate. The cooling component includes: a low-temperature thermostat, which is disposed through the conductive cooling structure; the refrigerator is disposed through the end of the low-temperature thermostat away from the conductive cooling structure; a primary cold head, which is connected to the output end of the refrigerator and located inside the low-temperature thermostat; and a secondary cold head, which is connected to the end of the primary cold head. The cooling component includes: a heat transfer aluminum strip, which is disposed on the outside of the secondary cooling head and the binding strap and is fixedly connected to the outer surface of the cooling screen; a copper thermal connector, which is disposed at the end of the heat transfer aluminum strip; a copper thermal connector connected to the heat transfer aluminum strip disposed on the outside of the secondary cooling head, which is located on the outside of the primary cooling head; and a connecting part, which is disposed within the conductive cooling structure and connected to the secondary cooling head. The connecting components include: a secondary guide block connected to the end of the secondary cold head away from the primary cold head; a secondary connector connected to the side of the secondary guide block away from the secondary cold head; and a cooling plate disposed at the end of the secondary connector away from the secondary guide block, with the cooling plate in contact with the superconducting coil.

2. The superconducting magnet system for conductive cooling of a cyclotron accelerator according to claim 1, characterized in that, The cold screen is located on the side of the superconducting magnet close to the Dewar. The Dewar and the cold screen form a first vacuum cavity, and the cold screen and the surface of the superconducting magnet form a second vacuum cavity.

3. The superconducting magnet system for conductive cooling of a cyclotron accelerator according to claim 2, characterized in that, Vacuum pumps and current leads are respectively installed on opposite sides of the other two refrigerators. The vacuum pump is installed above the conductive cooling structure to extract air from the inside of the superconducting magnet. The current lead is located below the conductive cooling structure and is electrically connected to the superconducting coil. The current lead is divided into a high-temperature end and a low-temperature end, which are connected to the high-temperature end through a superconducting connector. A heat sink is installed above the low-temperature end lead. Insulation is installed on the outside of the heat sink. A heat sink cooling strip is installed on the outside of the heat sink and the insulation. The heat sink cooling strip extends from the cold shield to wrap the heat sink for cooling. The low-temperature end of the current lead is welded to the cold shield. A low-temperature cavity is provided on the outside of the low-temperature end, and the low-temperature cavity is located outside the heat sink cooling strip and is connected to the second vacuum cavity. A container is provided on the outside of the high-temperature end of the current lead, and the container is located outside the low-temperature cavity and is welded to the Dewar. The container is connected to the first vacuum cavity.

4. The superconducting magnet system for conductive cooling of a cyclotron accelerator according to claim 3, characterized in that, The pull rod includes: The racetrack-shaped tie rods are in sets of two, and each set of racetrack-shaped tie rods is connected to a copper thermal connector located on the outside of the binding strap via a transition joint; Adjust the nut and connect it to the end of the racetrack-shaped tie rod away from the strapping via the transition joint; The racetrack-shaped tie rod, transition joint, and copper thermal connection and heat transfer aluminum strip located outside the binding strap are provided with a protective shell, and the protective shell is installed through the conductive cooling structure.

5. The superconducting magnet system for conductive cooling of a cyclotron accelerator according to claim 1, characterized in that, The conductive cooling structure is equipped with a protection system, which includes: two rectangular slots, one on the inner surface of the frame and the other on the middle plane; multiple junction cups, fixed in a linear array within one of the slots; eight diode groups, fixed in another slot by a clamping plate; a voltage divider resistor plate, disposed in the other slot and matched with the diode groups; each diode group is connected in parallel with one-eighth of the superconducting coil for quench protection, and each diode group includes two diodes connected in parallel.

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