Arc superconducting magnet system for proton acceleration

Abstract

The application relates to an arc-shaped superconducting magnet system for proton acceleration, which comprises an arc-shaped superconducting magnet, an ultralow-temperature system and a magnet suspension system, wherein the arc-shaped superconducting magnet comprises a dipole magnet, two quadrupole magnets and a magnet fastening structure; the ultralow-temperature system comprises a vacuum container, a cold shield structure, a liquid helium container, a gas return pipe, a refrigerating unit and a cold conducting structure; the magnet suspension system comprises a liquid helium container pull rod assembly and a cold shield structure pull rod assembly; the arc-shaped superconducting magnet provides a magnetic field required by proton acceleration, the ultralow-temperature system is used for providing a stable ultralow-temperature environment for the superconducting magnet, and the magnet suspension system keeps the arc-shaped superconducting magnet in a stable spatial physical position; the three are combined to form a complete arc-shaped superconducting magnet system suitable for proton acceleration; the application has the advantages of small volume, light mass, low operation cost, safer radiation protection and the like.

Description

Technical Field

[0001] This invention belongs to the field of superconducting electric engineering, specifically relating to an arc-shaped superconducting magnet system for proton acceleration, used in laser proton radiotherapy systems for proton acceleration. Background Technology

[0002] As the most ideal radiation therapy beam of the 21st century, the use of ion beams in tumor treatment has become increasingly common. Protons and heavy ions are charged particles, unlike conventional rays such as X-rays, gamma rays, and electron beams. Protons and heavy ions, possessing a certain energy, can concentrate their energy on tumors at different depths and locations after entering human tissue using SpreadOutBraggPeak (SOBP) technology, while minimizing damage to normal tissues. Although proton beam technology has been well-appointed in tumor treatment, due to its advanced technology and complex equipment, only a few countries worldwide have mastered this technology, and many technical shortcomings still need to be overcome. For example, the treatment terminal technology is complex, and the equipment is enormous, especially the rotating gantry supporting the multi-directional beam irradiation, which weighs hundreds of tons. Such a massive weight, coupled with the requirement for high-precision rotation control, greatly increases the difficulty of mechanical structure design. Meanwhile, a future research direction is to integrate proton therapy and heavy ion therapy into a single system to achieve combined treatment and reduce costs. Therefore, miniaturization and weight reduction are the development directions for next-generation radiotherapy devices. Superconducting magnets are characterized by their small size and ability to generate higher magnetic fields at liquid helium temperatures, which can reduce the acceleration and deflection radius of particles, thereby effectively reducing the size of the gantry. Therefore, applying superconducting magnet technology to proton radiotherapy systems is inevitable.

[0003] Chinese invention patent CN202210316405.0 discloses a proton accelerator therapy system, which incorporates a sliding secondary magnet B in the beam guidance system to better meet therapeutic requirements, but it uses a magnet. Chinese utility model patent CN201820142807.2 discloses an accelerator magnet with superior particle capture capabilities, significantly improving particle capture and control, maximizing the controllability of charged particles, and controlling them through continuous beam focusing to ultimately generate higher-energy X-rays with superior penetrating power, without using superconducting coils. Chinese invention patent CN202010843043.1 discloses a superconducting coil skeleton structure for a superconducting proton cyclotron accelerator, including a coil plate and a liquid helium tank plate. By providing a channel connecting the two receiving tanks on the liquid helium tank plate, a flow path for liquid helium during cooling can be provided. This skeleton structure is not an arc-shaped solenoid. The technologies and structures disclosed in the above patents are different from those of this invention. Summary of the Invention

[0004] To achieve miniaturization and weight reduction of proton radiotherapy systems, this invention proposes an arc-shaped superconducting magnet system for proton acceleration. The arc-shaped superconducting magnet generates the high-intensity magnetic field required for particle acceleration. Liquid helium immersion-refrigeration is used to ensure that the magnet operates stably at a high field in an ultra-low temperature environment for a long time. The corresponding magnet structural features are also disclosed.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] An arc-shaped superconducting magnet system for proton acceleration consists of an arc-shaped superconducting magnet, an ultra-low temperature system, and a magnet suspension system;

[0007] The arc-shaped superconducting magnet includes a diode magnet, a quadrupole magnet, and a magnet fastening structure; both the diode magnet and the quadrupole magnet are curved inclined solenoids with the same central axis of curvature and aligned at both ends; the magnet fastening structure fixes the relative positions of the diode magnet and the quadrupole magnet.

[0008] The cryogenic system consists of a liquid helium container, a cold shield structure, and a vacuum container fitted together from the inside out. It uses three refrigerators and a cooling structure for cooling and heat conduction. The arc-shaped superconducting magnet is fixed inside the liquid helium container. The liquid helium container, the cold shield structure, and the vacuum container all have curved arc tubes, and the bending center axis of the curved arc tubes coincides with the bending center axis of the arc-shaped superconducting magnet.

[0009] The magnet suspension system includes a tie rod assembly A and a tie rod assembly B. The tie rod assembly A stabilizes the liquid helium container and the arc-shaped superconducting magnet in the vacuum container, and the tie rod assembly B stabilizes the cold screen structure in the vacuum container.

[0010] Furthermore, the magnet fastening structure consists of a left end face positioning plate, a right end face positioning plate, a middle transition ring, and a left and right pull rod assembly. Both the left and right end face positioning plates have annular grooves and circumferential limiting blocks. One end of the diode magnet and the quadrupole magnet are embedded in the annular groove on the left end face positioning plate, and the other end is embedded in the annular groove on the right end face positioning plate. The circumferential limiting blocks limit the circumferential positions of the diode magnet and the quadrupole magnet, and the transition ring and the left and right pull rod assemblies tighten the entire arc-shaped superconducting magnet.

[0011] Furthermore, both the left and right pull rod assemblies are telescopic rod assemblies with positive and negative threads. The transition ring is located in the middle section of the arc-shaped superconducting magnet. One end of the left pull rod assembly is connected to the left end face positioning plate by a hinge, and the other end is connected to the transition ring by a hinge. One end of the right pull rod assembly is connected to the transition ring by a hinge, and the other end is connected to the right end face positioning plate by a hinge. The left and right end face positioning plates are relatively fastened by adjusting the length of the left and right pull rod assemblies.

[0012] Furthermore, the vacuum container consists of a vacuum container shell and a room temperature bent tube, forming a sealed structure with a vacuum environment inside and a room temperature environment outside; the cold screen structure consists of a cold screen shell and a low temperature bent tube; the liquid helium container consists of a liquid helium shell and an ultra-low temperature bent tube forming a sealed structure, and the arc-shaped superconducting magnet is placed inside the liquid helium container; the room temperature bent tube, the low temperature bent tube, the ultra-low temperature bent tube and the arc-shaped superconducting magnet have the same bending radius, and their bending center axes coincide after assembly; the vacuum container, the cold screen structure, and the liquid helium container are separated by a certain distance.

[0013] Furthermore, the refrigeration unit consists of a primary refrigerator, a secondary refrigerator a, and a secondary refrigerator b. The primary refrigerator conducts the cooling capacity to the cold shield structure through the cold conduction component a. The secondary refrigerator a connects to the current lead connector inside the arc-shaped superconducting magnet to perform segmented cooling of the current lead. The secondary refrigerator b conducts cooling capacity to the cold shield structure and the liquid helium container through the cold conduction component b and the condenser component respectively. The cold conduction component a, the cold conduction component b, and the condenser component are all made of materials with high thermal conductivity at low temperatures, and conduct the cooling capacity generated by the primary refrigerator, the secondary refrigerator a, and the secondary refrigerator b to the arc-shaped superconducting magnet to maintain its required ultra-low temperature environment.

[0014] Furthermore, a return gas pipe is welded onto the outer shell of the vacuum container. The return gas pipe contains a liquid delivery pipe and inlet / outlet valves for the transfer of liquid helium and gas in the liquid helium container. The low-temperature section of the return gas pipe is connected to the cold shield structure through a cooling component c.

[0015] Furthermore, both the pull rod assembly A and the pull rod assembly B are slender rod assemblies with adjustable length. One end of the pull rod assembly A is connected to the liquid helium container via a rotating bracket, and the other end is connected to the vacuum container via a rotating bracket. One end of the pull rod assembly B is connected to the cold shield structure via a rotating bracket, and the other end is connected to the vacuum container via a rotating bracket. The pull rod assemblies A and B suspend the liquid helium container and the cold shield structure inside the vacuum container.

[0016] Beneficial effects:

[0017] The arc-shaped superconducting magnet system for proton acceleration proposed in this invention generates the magnetic field environment required for proton acceleration through an arc-shaped superconducting magnet. A stable ultra-low temperature environment is formed by liquid helium immersion and refrigeration, providing the ultra-low temperature required for the normal operation of the superconducting magnet. The magnet suspension system keeps the arc-shaped superconducting magnet relatively stable inside the vacuum container. The superconducting magnet can generate a higher magnetic field than conventional magnets in the liquid helium temperature range. Moreover, the entire device system has a simple internal structure, small overall size, light weight, and low maintenance cost, which can achieve the goal of miniaturization and weight reduction of proton radiotherapy system equipment. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of the arc-shaped superconducting magnet system for proton acceleration according to the present invention;

[0019] Figure 2 This is a schematic diagram showing the installation position of the arc-shaped superconducting magnet system for proton acceleration according to the present invention.

[0020] Figure 3 This is a schematic diagram of the installation of the arc-shaped superconducting magnet of the present invention;

[0021] Figure 4 This is a schematic diagram of the overall shape of the present invention.

[0022] Explanation of reference numerals in the attached diagram: 1 is a vacuum container, 1-1 is the outer shell of the vacuum container, 1-2 is a room temperature bent tube, 2 is a cold shield structure, 2-1 is the outer shell of the cold shield, 2-2 is a low temperature bent tube, 3 is a liquid helium container, 3-1 is the outer shell of the liquid helium, 3-2 is a cryogenic bent tube, 4 is an arc-shaped superconducting magnet, 4-1 is a dipole magnet, 4-2 is a quadrupole magnet, 4-3 is the left end face positioning plate, 4-4 is the left tie rod assembly, 4-5 is a transition ring, 4-6 is the right tie rod assembly, 4-7 is the right end face positioning plate, 5 is the first-stage refrigerator, 5-1 is the cold conduction component a, 6 is the second-stage refrigerator a, 7 is the return gas pipe, 7-1 is the cold conduction component c, 8 is the second-stage refrigerator b, 8-1 is the cold conduction component b, 8-2 is the condenser assembly, 9 is the tie rod assembly A, 10 is the tie rod assembly B. Detailed Implementation

[0023] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the protection scope of the present invention.

[0024] like Figure 1 , Figure 2 , Figure 4As shown, the arc-shaped superconducting magnet system for proton acceleration of the present invention includes an arc-shaped superconducting magnet 4, a cryogenic system, and a magnet suspension system. The arc-shaped superconducting magnet 4 includes a diode magnet 4-1, a quadrupole magnet 4-2, and a magnet fastening structure that fixes the relative positions of the two magnets. The arc-shaped superconducting magnet 4 provides the necessary magnetic field environment for proton acceleration after being energized and excited. The cryogenic system includes a vacuum container 1, a cold shield structure 2, a liquid helium container 3, the arc-shaped superconducting magnet 4, a return gas pipe 7, a refrigeration unit, and a cooling structure. It provides a stable cryogenic environment for the normal operation of the arc-shaped superconducting magnet 4 through liquid helium immersion and refrigeration. The magnet suspension system includes the arc-shaped superconducting magnet 4, the tie rod assembly A9 of the liquid helium container 3, and the tie rod assembly B10 of the cold shield structure 2. The arc-shaped superconducting magnet 4, the liquid helium container 3, and the cold shield structure 2 are suspended in the vacuum container 1. The above three parts are combined to form a complete arc-shaped superconducting magnet system for proton acceleration.

[0025] The vacuum container 1 consists of a vacuum container shell 1-1 and a room temperature bent tube 1-2, forming a sealed structure. The exterior of the vacuum container 1 is a room temperature environment, while the interior is a vacuum environment. The cold shield structure 2 consists of a cold shield shell 2-1 and a low temperature bent tube 2-2, located inside the vacuum container. The liquid helium container 3 consists of a liquid helium shell 3-1 and an ultra-low temperature bent tube 3-2, forming a sealed structure surrounded by the cold shield structure 2. The liquid helium container 3 contains a certain amount of liquid helium. The arc-shaped superconducting magnet 4 is placed inside the liquid helium container 3. In particular, the room temperature bent tube 1-2, the low temperature bent tube 2-2, and the ultra-low temperature bent tube 3-2 have the same bending radius as the diode magnet 4-1 and the quadrupole magnet 4-2 in the arc-shaped superconducting magnet 4. After overall assembly, the bending center axes of each bent tube coincide. The vacuum container 1, the cold shield structure 2, and the liquid helium container 3 are separated by a certain distance.

[0026] like Figure 2 , Figure 3As shown, in the arc-shaped superconducting magnet 4 of the present invention, both the diode magnet 4-1 and the quadrupole magnet 4-2 are curved inclined solenoids with the same bending central axis. The magnet fastening structure consists of a left end face positioning plate 4-3, a left pull rod assembly 4-4, a transition ring 4-5, a right pull rod assembly 4-6, and a right end face positioning plate 4-7, wherein the left pull rod assembly 4-4 and the right pull rod assembly 4-6 are both slender rods with adjustable lengths. Both the left end face positioning plate 4-3 and the right end face positioning plate 4-7 have annular grooves and circumferential limiting blocks. One end of the diode magnet 4-1 and the quadrupole magnet 4-2 are embedded in the annular groove on the left end face positioning plate 4-3, and the other end is embedded in the annular groove on the right end face positioning plate 4-7. The transition ring 4-5 is located in the middle section of the arc-shaped superconducting magnet 4. One end of the left pull rod group 4-4 is connected to the left end face positioning plate 4-3 by a hinge, and the other end is connected to the left side of the transition ring 4-5 by a hinge. One end of the right pull rod group 4-6 is connected to the right side of the transition ring 4-5 by a hinge, and the other end is connected to the right end face positioning plate 4-7 by a hinge. Finally, by adjusting the length of the left and right pull rod groups, the left and right end face positioning plates are pulled relatively tight, thereby fixing the relative position between the diode magnet 4-1 and the quadrupole magnet 4-2.

[0027] like Figure 1 As shown, the magnet suspension system includes a pull rod assembly A9 and a pull rod assembly B10. Both pull rod assemblies A and B are slender rod assemblies with adjustable length. One end of pull rod assembly A9 is connected to the liquid helium container 3 via a rotating bracket, and the other end is connected to the vacuum container 1 via a rotating bracket, thereby stabilizing the position of the arc-shaped superconducting magnet 4 in the vacuum container 1. One end of pull rod assembly B10 is connected to the cold screen structure 2 via a rotating bracket, and the other end is connected to the vacuum container 1 via a rotating bracket, thereby stabilizing the position of the cold screen structure 2 in the vacuum container 1.

[0028] like Figure 1 As shown, the arc-shaped superconducting magnet system for proton acceleration of the present invention employs three refrigerators and a cooling conduction structure. The three refrigerators include a primary refrigerator 5, a secondary refrigerator a6, and a secondary refrigerator b8. The primary refrigerator 5 conducts all cooling capacity to the cold shield structure 2 via a cooling conduction component a5-1. The secondary refrigerator a6 provides segmented cooling to the current leads of the arc-shaped superconducting magnet 4 via an insulated electrical connector connected to the magnet. The secondary refrigerator b8 conducts cooling capacity to the cold shield structure 2 and the liquid helium container 3 via cooling conduction component b8-1 and a condenser component 8-2, respectively. Specifically, the cooling conduction component a5-1, cooling conduction component b8-1, and condenser component 8-2 are all made of materials with high thermal conductivity at low temperatures, conducting the cooling capacity generated by the three refrigerators to the arc-shaped superconducting magnet 4 to maintain its required ultra-low temperature environment.

[0029] like Figure 1 , Figure 2 As shown, a return gas pipe 7 is welded onto the outer shell 1-1 of the vacuum container. The return gas pipe 7 contains a liquid delivery pipe and an inlet / outlet valve for the transfer of liquid helium and gas in the liquid helium container 3. To reduce system heat leakage generated by the return gas pipe 7, a cooling component c7-1 is provided at the middle position of the return gas pipe 7 to connect the return gas pipe 7 to the cold shield structure 2, thereby realizing temperature segmentation of the return gas pipe 7.

Claims

1. An arc superconducting magnet system for proton acceleration, characterized by: The arc-shaped superconducting magnet, the ultra-low temperature system and the magnet suspension system are composed of; The arc-shaped superconducting magnet comprises a dipole magnet and a quadrupole magnet and a magnet fastening structure; the dipole magnet and the quadrupole magnet are both curved skew solenoid-shaped and have the same curved central axis, and the two ends are aligned; the magnet fastening structure fixes the relative positions of the dipole magnet and the quadrupole magnet; The ultra-low temperature system is composed of a liquid helium container, a cold shield structure and a vacuum container from inside to outside, and adopts three refrigerators and a cold conducting structure for refrigeration and cold conduction; the arc-shaped superconducting magnet is relatively fixed inside the liquid helium container; the liquid helium container, the cold shield structure and the vacuum container are all provided with curved circular tubes, and the curved central axes of the curved circular tubes coincide with the curved central axis of the arc-shaped superconducting magnet; The magnet suspension system comprises a pull rod assembly A and a pull rod assembly B; the pull rod assembly A stabilizes the positions of the liquid helium container and the arc-shaped superconducting magnet in the vacuum container; and the pull rod assembly B stabilizes the position of the cold shield structure in the vacuum container; The refrigeration group is composed of a first-level refrigerator, a second-level refrigerator a and a dipole refrigerator b; the first-level refrigerator transmits the refrigeration capacity to the cold shield structure through a cold conducting assembly a; the second-level refrigerator a performs segmented refrigeration on the current lead by being connected with the current lead joint in the arc-shaped superconducting magnet; and the second-level refrigerator b respectively transmits the cold capacity to the cold shield structure and the liquid helium container through a cold conducting assembly b and a condenser assembly; The magnet fastening structure is composed of a left end face positioning plate, a right end face positioning plate, a transition ring in the middle and a left pull rod group and a right pull rod group; the left end face positioning plate and the right end face positioning plate are both provided with an annular cutout and a circumferential limiting block; one end of the dipole magnet and the quadrupole magnet is embedded in the annular cutout on the left end face positioning plate, and the other end is embedded in the annular cutout on the right end face positioning plate; the circumferential limiting block limits the circumferential positions of the dipole magnet and the quadrupole magnet; and the arc-shaped superconducting magnet is pulled tight as a whole through the transition ring and the left pull rod group and the right pull rod group.

2. Arc-shaped superconducting magnet system for proton acceleration according to claim 1, characterized in that The left pull rod group and the right pull rod group are both telescopic rod assemblies with positive and negative threads; the transition ring is located in the middle segment of the arc-shaped superconducting magnet; one end of the left pull rod group is connected with the left end face positioning plate through a hinge, and the other end is connected with the transition ring through a hinge; one end of the right pull rod group is connected with the transition ring through a hinge, and the other end is connected with the right end face positioning plate through a hinge; and the left end face positioning plate and the right end face positioning plate are relatively fastened by adjusting the lengths of the left pull rod group and the right pull rod group.

3. The arc-shaped superconducting magnet system for proton acceleration of claim 1, wherein, The vacuum container is composed of a vacuum container shell and a room temperature bent pipe and has a sealed structure; the internal environment is a vacuum environment, and the external environment is a room temperature environment; the cold shield structure is composed of a cold shield shell and a low temperature bent pipe; the liquid helium container is composed of a liquid helium shell and an ultra-low temperature bent pipe and has a sealed structure; the arc-shaped superconducting magnet is arranged inside the liquid helium container; the room temperature bent pipe, the low temperature bent pipe and the ultra-low temperature bent pipe have the same bending radius as the arc-shaped superconducting magnet; the bending central axes coincide after overall assembly; and the vacuum container, the cold shield structure and the liquid helium container are separated by a certain distance.

4. The arc-shaped superconducting magnet system for proton acceleration of claim 1, wherein, The cold conducting component a, the cold conducting component b and the condenser component are made of material with high thermal conductivity at low temperature, and the cold energy generated by the primary refrigerating machine, the secondary refrigerating machine a and the secondary refrigerating machine b is conducted to the arc-shaped superconducting magnet for maintaining the required ultra-low temperature environment.

5. The arc-shaped superconducting magnet system for proton acceleration of claim 3, wherein, A gas return pipe is welded on the vacuum container shell, and the gas return pipe contains a liquid delivery pipeline and an inlet and outlet valve port for conveying liquid helium and gas in the liquid helium container. The low-temperature section of the gas return pipe is connected to the cold shield structure through a cold conducting component c.

6. The arc-shaped superconducting magnet system for proton acceleration of claim 1, wherein, The pull rod component A and the pull rod component B are both length-adjustable slender rod components. One end of the pull rod component A is connected to the liquid helium container through a rotating support, and one end is connected to the vacuum container through a rotating support. One end of the pull rod component B is connected to the cold shield structure through a rotating support, and one end is connected to the vacuum container through a rotating support. The pull rod component A and the pull rod component B suspend the liquid helium container and the cold shield structure inside the vacuum container.

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