Liquid helium supply mechanism

Abstract

The application is a liquid helium supply mechanism, which provides cold source for low-temperature superconducting material in superconducting particle radiotherapy equipment. The mechanism comprises a liquid helium preparation mechanism for preparing liquid helium by using helium gas, and the prepared liquid helium flows into a liquid helium terminal for cooling the low-temperature superconducting material. The mechanism also comprises a liquid helium compensation mechanism, which collects the helium gas vaporized due to heat absorption of the low-temperature superconducting material in each liquid helium terminal and delivers the helium gas to the liquid helium preparation mechanism. The liquid helium supply mechanism of the application comprises the liquid helium preparation mechanism and the liquid helium compensation mechanism, which overcomes the deficiency of the current liquid helium supply equipment that only provides liquid helium preparation equipment and cannot automatically compensate liquid helium.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of liquid helium supply mechanism. BACKGROUND

[0002] Particle radiation therapy center contains many magnetic components, the meaning of superconducting particle radiation therapy center is that most of the magnetic components in the center are superconducting, so as to realize the miniaturization of the device and reduce the daily operating cost. If the excitation coil in the superconducting magnetic component adopts low-temperature superconducting material, liquid helium refrigeration is needed. A large number of liquid helium superconducting magnetic components need a large amount of liquid helium, and a separate liquid helium production device needs to be configured. Helium liquefaction is a mature technology, and has realized large-scale production. Its production equipment is complex and bulky. However, the amount of liquid helium used by the liquid helium superconducting therapy center is limited, and the bulky and complex helium liquefaction equipment does not need to be copied. Miniaturization of the liquid helium production device is the direction of exploration. On the other hand, the liquid helium in the liquid helium superconducting magnetic component will evaporate due to heat leakage, and the timely compensation of the liquid helium is a complex work, and the current miniaturized liquid helium production device cannot have the automatic compensation function of the liquid helium. SUMMARY

[0003] The present application aims at the deficiency that the liquid helium production device for providing liquid helium refrigeration for the current superconducting particle radiation therapy center cannot have the automatic compensation of liquid helium, and provides a liquid helium supply mechanism which has the functions of liquid helium production and compensation.

[0004] The technical scheme adopted by the present application to achieve the technical purpose is a liquid helium supply mechanism which provides a cold source for low-temperature superconducting material in a superconducting particle radiation therapy device, comprising a liquid helium preparation mechanism for preparing liquid helium by using helium gas cooling, wherein the liquid helium prepared by the liquid helium preparation mechanism flows into a liquid helium terminal which cools the low-temperature superconducting material; and further comprising a liquid helium compensation mechanism; the liquid helium compensation mechanism collects helium gas which is vaporized due to heat absorption when each liquid helium terminal cools the low-temperature superconducting material, and delivers the helium gas to the liquid helium preparation mechanism.

[0005] Further, in the above-mentioned liquid helium supply mechanism: the liquid helium preparation mechanism comprises a gas reservoir for storing helium gas, a gas pump and a cooler, and a refrigerator; the gas pump pumps the helium gas in the gas reservoir into the cooler, and the cooler is a cold end heat exchanger of the refrigerator.

[0006] Further, in the above-mentioned liquid helium supply mechanism: the gas pump comprises a barrel-shaped cavity A with an open end and a flange, a piston with a push-pull rod is inserted into the cavity A from the open end with the flange, the open end with the flange of the cavity A is connected with a pen-type linear motor, and the push-pull rod of the piston penetrates through the linear motor.

[0007] Further, in the liquid helium supply mechanism, the bottom of the cavity A is communicated with a T-shaped helium pipe AA, one end of the horizontal pipe of the T-shaped helium pipe AA is communicated with the bottom of the cavity A, and the other end is communicated with the cooler through a helium passage AB; an extension of the vertical pipe of the T-shaped helium pipe AA is communicated with the helium reservoir, a valve A is arranged on the horizontal pipe of the T-shaped helium pipe AA near the bottom of the cavity A, and a valve B is arranged on the vertical pipe of the T-shaped helium pipe AA.

[0008] Further, in the liquid helium supply mechanism, the helium passage AB is a plate-type helium passage, which comprises a triangular upper plate and a triangular lower plate; the triangular upper plate and the triangular lower plate are superimposed, two sides of which are sealedly connected with each other, and the other side is communicated with the cooler, and a gap is formed between the triangular upper plate and the triangular lower plate to realize the connection between the helium inlet and the cooler, so that the helium enters the gap through the helium inlet and is diffused to be discharged to the cooler in a strip-shaped surface.

[0009] Further, in the liquid helium supply mechanism, the cooler is a two-stage Stirling refrigeration mechanism, which comprises a primary refrigeration mechanism and a secondary refrigeration mechanism.

[0010] The primary refrigeration mechanism comprises a compressor B, a hot-end heat exchanger B, a regenerator A, a cold-end heat exchanger B and an expander B which are communicated in sequence.

[0011] The secondary refrigeration mechanism comprises a compressor C, a hot-end heat exchanger C, a regenerator B, a cold-end heat exchanger C and an expander C which are communicated in sequence.

[0012] The hot-end heat exchanger C is the cold-end heat exchanger B, and the cold-end heat exchanger C is the cooler.

[0013] Further, in the liquid helium supply mechanism, the hot-end heat exchanger B, the cold-end heat exchanger B or the cooler are all heat exchangers, and have the same heat exchanger structure.

[0014] Further, in the liquid helium supply mechanism, the liquid helium preparation mechanism and the liquid helium compensation mechanism are arranged in a vacuum box.

[0015] The liquid helium supply mechanism of the present application not only comprises the liquid helium preparation mechanism but also comprises the liquid helium compensation mechanism, which overcomes the deficiency that the current liquid helium supply equipment only provides the liquid helium preparation equipment and cannot automatically compensate the liquid helium.

[0016] The present application will be described in detail below in combination with the drawings and specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0017] ATTACHMENTFigure 1 , assembly drawing of liquid helium production and compensation mechanism;

[0018] attached Figure 2 , liquid helium production and compensation mechanism after adding vacuum box;

[0019] attached Figure 3 , assembly drawing of liquid helium production mechanism;

[0020] attached Figure 4 , cross-sectional structure drawing of compressor A;

[0021] Figure 5 , cross-sectional structure drawing of plate type helium passage;

[0022] Figure 6 , cross-sectional structure drawing of cooler;

[0023] Figure 7 , cross-sectional structure drawing of heat exchanger;

[0024] Figure 8 , assembly drawing of primary refrigeration mechanism;

[0025] Figure 9 , structure drawing of hot end heat exchanger B;

[0026] Figure 10 , structure drawing of regenerator A;

[0027] Figure 11 , assembly drawing of secondary refrigeration mechanism;

[0028] Figure 12 , cross-sectional structure drawing of regenerator B;

[0029] Figure 13 , appearance drawing of vacuum box;

[0030] Figure 14 , simple structure drawing of liquid helium production and compensation mechanism;

[0031] Figure 15 , working principle drawing of primary refrigeration mechanism No.1;

[0032] Figure 16 , working principle drawing of primary refrigeration mechanism No.2;

[0033] Figure 17 , working principle drawing of primary refrigeration mechanism No.3;

[0034] Figure 18 , working principle drawing of primary refrigeration mechanism No.4;

[0035] Figure 19 , working principle drawing of primary refrigeration mechanism No.5;

[0036] Figure 20 , working principle of the secondary refrigeration mechanism;

[0037] Figure 21 , working principle of the liquid helium production and compensation No. 1;

[0038] Figure 22 , working principle of the liquid helium production and compensation No. 2;

[0039] Figure 23 , working principle of the liquid helium production and compensation No. 3;

[0040] Figure 24 , working principle of the liquid helium production and compensation No. 4.

[0041] Symbols in the figure:

[0042] 1, liquid helium production mechanism, 1-1, air pump, 1-1-1, barrel-shaped cavity A, 1-1-2, piston with push-pull rod, 1-1-3, sealing ring, 1-1-4, pen-type linear motor; 1-2, gas tank, 1-3-1, valve A, 1-3-2, valve B, 1-4, cooler, 1-4-1, fixed plate, 1-4-2, fine helium gas pipeline, 1-4-3, rectangular box, 1-4-4, partition, 1-5, frame type heat insulation pad A, 1-6, heat exchanger, 1-7, throttle valve, 1-8, gas-liquid separator, 1-9, liquid helium distributor, 1-10, liquid helium terminal;

[0043] 2, primary refrigeration mechanism, 2-1, compressor B, 2-1-1, cylindrical cavity B, 2-2, hot end heat exchanger B, 2-3, frame type heat insulation pad B, 2-4, regenerator A, 2-4-1, box A, 2-4-2, heat absorbing material A, 2-5, frame type heat insulation pad C, 2-6, cold end heat exchanger B, 2-7, expander B;

[0044] 3, secondary refrigeration mechanism, 3-1, compressor C, 3-2, regenerator B, 3-2-1, box B, 3-2-2, heat absorbing material B, 3-3, expander C;

[0045] 4, two-stage Stirling refrigeration mechanism;

[0046] 5. Auxiliary gas-liquid channels, 5-1-1, T-shaped helium pipe AA, 5-1-2, plate helium channel AB, 5-1-3, helium pipe AC, 5-1-4, helium pipe AD, 5-1-5, plate helium channel AE, 5-1-6, plate helium channel AF, 5-1-7, liquid helium pipe AG, 5-1-8, liquid helium outlet pipe AH, 5-1-9, helium injection pipe AI, 5-2-1, plate helium channel BA, 5-2-2, cooling water pipe BB, 5-2-3, plate helium channel BC, 5-3-1, plate helium channel CA, 5-3-2, plate helium channel CB, 5-3-3, plate helium channel CC, 5-3-4, plate helium channel CD;

[0047] 6. Vacuum chamber. Detailed Implementation

[0048] This embodiment is a liquid helium supply mechanism that provides a cold source for the cryogenic superconducting material in a superconducting particle radiotherapy device. It includes a liquid helium preparation mechanism 1 that uses helium gas to cool and prepare liquid helium, and the liquid helium from the liquid helium preparation mechanism flows into liquid helium terminals 1-10 that cool the cryogenic superconducting material. It also includes a liquid helium compensation mechanism that collects the helium gas that is absorbed heat and vaporized by each liquid helium terminal 1-10 due to the cooling of the cryogenic superconducting material, and transfers this helium gas to the liquid helium preparation mechanism 1.

[0049] In this embodiment, the liquid helium consumed due to heat leakage can be automatically compensated after the liquid helium required for the superconducting magnetic components of the superconducting particle radiotherapy center is produced. If the liquid helium required for the start-up of the liquid helium superconducting particle radiotherapy center is procured and injected, the liquid helium production and compensation mechanism can only perform the automatic compensation function of liquid helium.

[0050] like Figure 1 As shown, this is the liquid helium production and replenishment mechanism in the liquid helium supply system of this embodiment. Figure 1 As shown, it includes a liquid helium preparation mechanism 1 equipped with gas storage tanks 1-2, a secondary Stirling refrigeration mechanism 4 consisting of a primary refrigeration mechanism 2 and a secondary refrigeration mechanism 3 connected in series, several auxiliary gas-liquid channels 5, and a vacuum chamber 6. The cooler 1-4 in the liquid helium preparation mechanism 1 replaces the cold end heat exchanger in the secondary refrigeration mechanism 3, and the auxiliary gas-liquid channels 5 connect the relevant components in the liquid helium preparation mechanism 1 and the secondary Stirling refrigeration mechanism 4.

[0051] In this embodiment, the refrigerator is a two-stage Stirling refrigerator mechanism 4 including a primary refrigeration mechanism 2 and a secondary refrigeration mechanism 3; the primary refrigeration mechanism 2 includes a compressor B2-1, a hot-end heat exchanger B2-2, a regenerator A2-4, a cold-end heat exchanger B2-6, and an expander B2-7 connected in sequence; the secondary refrigeration mechanism 3 includes a compressor C3-1, a hot-end heat exchanger C, a regenerator B3-2, a cold-end heat exchanger C, and an expander C3-3 connected in sequence; the hot-end heat exchanger C is the cold-end heat exchanger B2-6, and the cold-end heat exchanger C is the cooler 1-4. In this embodiment, the hot-end heat exchanger B2-2, the cold-end heat exchanger B2-6, or the cooler 1-4 all perform heat exchange and have the same heat exchanger structure.

[0052] Here, A, B, and C are used to distinguish modules with the same structure arranged in different places.

[0053] As shown in Figure 2 , the vacuum box 6 accommodates the liquid helium supply device of this embodiment.

[0054] Figure 3 As shown in , the liquid helium preparation mechanism 1 includes a gas tank 1-2 and a gas pump 1-1, and the gas pump 1-1 is used to extract helium gas from the gas tank 1-2 to prepare liquid helium.

[0055] Figure 3 Figure 4 As shown in , the gas pump 1-1 actually has the structure of a compressor and includes a cylindrical cavity A1-1-1 with an open end and a flange, a piston 1-1-2 with a push-pull rod inserted into the cavity A1-1-1 from the open end with the flange, two sealing rings 1-1-3 embedded at both ends of the piston 1-1-2, the sealing rings 1-1-3 tightly fitted with the inner wall of the cavity A1-1-1, and a pen-type linear motor 1-1-4 connected to the open end with the flange of the cavity A1-1-1, and the push-pull rod of the piston 1-1-2 passes through the linear motor 1-1-4.

[0056] In the pen-type linear motor 1-1-4 and the push-pull rod of the piston 1-1-2, regularly arranged magnetic blocks are respectively installed, and the two groups of magnetic blocks interact to generate a push-pull force. If the push-pull force is to be increased, the number of magnetic blocks needs to be increased, which will increase the length of the pen-type linear motor 1-1-4. The pen-type linear motor 1-1-4 has the characteristics of fast response speed and high push-pull frequency.

[0057] The bottom of the cavity A1-1-1 is communicated with a T-shaped helium pipeline AA5-1-1, one end of the horizontal pipeline of the T-shaped helium pipeline AA5-1-1 is communicated with the bottom of the cavity A1-1-1, the other end is butted with the helium passage AB5-1-2, the vertical pipeline of the T-shaped helium pipeline AA5-1-1 is communicated with the gas reservoir 1-2, a valve A1-3-1 is installed on the horizontal pipeline of the T-shaped helium pipeline AA5-1-1 near the bottom of the cavity A1-1-1, a valve B1-3-2 is installed on the vertical pipeline of the T-shaped helium pipeline AA5-1-1.

[0058] The helium passage AB5-1-2 is a plate type helium passage, as shown in Figure 5 , including a triangular upper plate 5-1-2-1 and a triangular lower plate 5-1-2-2; the triangular upper plate 5-1-2-1 and the triangular lower plate 5-1-2-2 are superimposed, two sides of which are sealed and connected to each other, and an angle between them forms a helium inlet interface 5-1-2-3 connected with the horizontal pipeline of the T-shaped helium pipeline AA5-1-1, the other side is connected with the cooler 1-4, a gap 5-1-2-4 is formed between the triangular upper plate 5-1-2-1 and the triangular lower plate 5-1-2-2, so that the helium inlet interface 5-1-2-3 is connected with the cooler 1-4, helium enters the gap 5-1-2-4 through the helium inlet interface 5-1-2-3, diffuses and is discharged to the cooler 1-4 in a strip-shaped surface.

[0059] As shown in Figure 3 and Figure 4 , the helium passage AB5-1-2 is processed in a cross section, helium pressed by the air pump 1-1 enters the inside of the helium passage AB5-1-2 through a round hole, and then diffuses and is discharged in a strip-shaped surface. The plate type helium passages described below all adopt similar principles, some of which adopt strip-shaped surface for helium inlet and strip-shaped surface for helium outlet, and some of which adopt circular surface for helium inlet and strip-shaped surface for helium outlet, when helium is introduced in a circular surface, it is equivalent to Figure 5 enlargement of the round hole.

[0060] The helium passage AB5-1-2 is communicated with the side wall of the cooler 1-4.

[0061] The cooler 1-4 in this embodiment adopts one of the standard styles of heat exchangers, as shown in Figure 6 , which is specially modified for a liquid helium preparation and compensation mechanism, and the following described heat exchangers all adopt similar structures with only slight differences.

[0062] As shown in Figure 3 and Figure 6As shown in the drawings, the cooler 1-4 comprises two fixed plates 1-4-1, a set of horizontally and vertically densely arranged thin helium gas pipes 1-4-2 passing through the two fixed plates 1-4-1 and being flush with the outer end faces of the two fixed plates 1-4-1, the combination of the two fixed plates 1-4-1 and the set of horizontally and vertically densely arranged thin helium gas pipes 1-4-2 constituting the longitudinal helium gas passage of the cooler 1-4, the two fixed plates 1-4-1 and the set of horizontally and vertically densely arranged thin helium gas pipes 1-4-2 being placed in a rectangular box 1-4-3 with one end open, the four side walls of the two fixed plates 1-4-1 being connected with the four inner walls of the rectangular box 1-4-3, the outer end face of one fixed plate 1-4-1 being flush with the open end of the rectangular box 1-4-3, and a gap being left between the outer end face of the other fixed plate 1-4-1 and the bottom surface inside the rectangular box 1-4-3, a strip-shaped hole being formed in the side wall of the rectangular box 1-4-3 at the gap, the strip-shaped hole being butted against the plate-type helium gas passage AB5-1-2, and a set of baffles 1-4-4 with the surface parallel to the bottom surface of the rectangular box 1-4-3 and the length shorter than the distance between the opposite inner walls being installed between the two opposite inner walls of the rectangular box 1-4-3, each baffle 1-4-4 having three side walls connected with the inner walls of the rectangular box 1-4-3, and the baffles 1-4-4 being staggered to constitute the transverse gas-liquid passage of the cooler 1-4 together with the rectangular box 1-4-3, a gas inlet and outlet hole being formed in the side wall of the rectangular box 1-4-3 at the inlet and outlet positions of the gas-liquid transverse passage, the gas inlet and outlet hole can be a strip-shaped hole or a circular hole, the number of the baffles 1-4-4 being even, so that the inlet and outlet of the gas-liquid transverse passage are located at the opposite sides of the rectangular box 1-4-3, and the number of the baffles 1-4-4 being odd, so that the inlet and outlet of the gas-liquid transverse passage are located at the same side of the rectangular box 1-4-3, and specifically to the cooler 1-4, the number of the baffles 1-4-4 is even, the gas inlet and outlet hole is a strip-shaped hole, and the transverse gas-liquid passage is a helium gas passage.

[0063] The open end of the rectangular box 1-4-3 is connected with one end of a frame-type heat insulation pad A1-5, and the other end of the frame-type heat insulation pad A1-5 is connected with a heat exchanger 1-6.

[0064] As shown in the drawings, Figure 3 , Figure 6 and Figure 7 , the heat exchanger 1-6 has basically the same structure as the cooler 1-4, with the only difference being that the number of the baffles is odd.

[0065] The open end of the heat exchanger 1-6 is connected with the frame-type heat insulation pad A1-5, and the bottom end is communicated with a helium gas pipe AC5-1-3, and a throttle valve 1-7 is installed on the helium gas pipe AC5-1-3.

[0066] The throttle valve 1-7 is selected from existing throttle valves.

[0067] The other end of helium pipeline AC5-1-3 is connected with a gas-liquid separator 1-8 from above, the upper part of gas-liquid separator 1-8 is connected with another helium pipeline AD5-1-4, the other end of helium pipeline AD5-1-4 is connected with a plate type helium passage AE5-1-5, plate type helium passage AE5-1-5 is connected with one strip-shaped gas inlet and outlet hole of horizontal helium passage of heat exchanger 1-6, the other strip-shaped gas inlet and outlet hole of horizontal helium passage of heat exchanger 1-6 is connected with one end of plate type helium passage AF5-1-6, the other end of plate type helium passage AF5-1-6 is connected with gas reservoir 1-2, the lower part of gas-liquid separator 1-8 is connected with a liquid helium pipeline AG5-1-7, the other end of liquid helium pipeline AG5-1-7 is connected with a liquid helium distributor 1-9, liquid helium distributor 1-9 is connected with a plurality of liquid helium pipelines AH5-1-8, one end surface of gas reservoir 1-2 is connected with a helium injection pipeline AI5-1-9.

[0068] As shown in Figure 8 , the primary refrigeration mechanism 2 in the secondary Stirling refrigeration mechanism 4 comprises a compressor B2-1, which has the same structure as gas pump 1-1, except that the cavity B2-1-1 is a cylinder with flanges at both ends, one end of cavity B2-1-1 is connected with a plate type helium passage BA5-2-1, plate type helium passage BA5-2-1 is connected with a strip-shaped hole on the side wall of the bottom of hot end heat exchanger B2-2, and further connected with the longitudinal helium passage of hot end heat exchanger B2-2.

[0069] As shown in Figure 8 and Figure 9 , the structure of hot end heat exchanger B2-2 is basically the same as cooler 1-4, except that the number of partitions is odd, the horizontal gas-liquid passage is a cooling water passage, the water inlet and outlet holes are circular holes, the water inlet and outlet circular holes of horizontal cooling water passage are respectively connected with a cooling water pipeline BB5-2-2, the open end of hot end heat exchanger B2-2 is connected with a frame type heat insulation pad B2-3, and frame type heat insulation pad B2-3 is connected with a regenerator A2-4.

[0070] As shown in Figure 8 and Figure 10As shown, the regenerator A2-4 includes a box A2-4-1 with two open ends and flanges, the box A2-4-1 is filled with heat-absorbing material A2-4-2, one end of the box A2-4-1 is connected with the frame-shaped heat-insulating pad B2-3, one end of the box A2-4-1 is connected with another frame-shaped heat-insulating pad C2-5, the frame-shaped heat-insulating pad C2-5 is connected with a cold-end heat exchanger B2-6, the structure of the cold-end heat exchanger B2-6 is the same as that of the cooler 1-4, the open end of the cold-end heat exchanger B2-5 is connected with the frame-shaped heat-insulating pad C2-5, the lateral strip-shaped hole at the bottom of the cold-end heat exchanger B2-6 is connected with a plate-shaped helium passage BC5-2-3, and then the longitudinal helium passage of the cold-end heat exchanger B2-6 is connected with the plate-shaped helium passage BC5-2-3, and the plate-shaped helium passage BC5-2-3 is connected with an expander B2-7, which has the same structure as the compressor B2-1.

[0071] As shown in Figure 11 , the secondary refrigeration mechanism 3 in the secondary Stirling refrigeration mechanism 4 includes a compressor C3-1, which has the same structure as the compressor B2-1, and one open end of the cavity C3-1-1 of the compressor C3-1 is connected with a plate-shaped helium passage CA5-3-1, the plate-shaped helium passage CA5-3-1 is connected with one strip-shaped gas inlet and outlet hole of the transverse helium passage of the cold-end heat exchanger B2-6 in the primary refrigeration mechanism 2, and the other strip-shaped gas inlet and outlet hole of the transverse helium passage is connected with a plate-shaped helium passage CB5-3-2, and the other end of the plate-shaped helium passage CB5-3-2 is connected with a regenerator B3-2.

[0072] As shown in Figure 11 and Figure 12 , Figure 12 is a sectional view of the regenerator B3-2, the box B3-2-1 of the regenerator B3-2 is filled with heat-absorbing material B3-2-2, two strip-shaped helium passage holes are opened on the upper and lower surfaces of the heat-absorbing material B3-2-2 on the two side walls of the box B3-2-1, one of the strip-shaped helium passage holes is connected with the plate-shaped helium passage CB5-3-2, and the other strip-shaped helium passage hole is connected with a plate-shaped helium passage CC5-3-3, the plate-shaped helium passage CC5-3-3 is connected with one strip-shaped gas inlet and outlet hole of the transverse helium passage of the cooler 1-4 in the liquid helium preparation mechanism (1), the other strip-shaped gas inlet and outlet hole of the transverse helium passage of the cooler 1-4 is connected with a plate-shaped helium passage CD5-3-4, and the other end of the plate-shaped helium passage CD5-3-4 is connected with an expander C3-3, which has the same structure as the compressor B2-1.

[0073] As shown in Figure 2 and Figure 13As shown, the vacuum box 6 is a cuboid connected with a small cylinder, the vacuum box 6 is hollow, and a plurality of through holes are formed on the vacuum box 6, one of the through holes is for the helium injection pipeline AI5-1-9 to pass through, two of the through holes are for two cooling water channels BB5-2-2 to pass through, and a plurality of through holes are formed on the small cylinder and are for a plurality of liquid helium lead-out pipelines AG5-1-7 on the liquid helium distributor 1-9 to pass through, wherein the helium injection pipeline AI5-1-9 and the plurality of liquid helium lead-out pipelines AG5-1-7 on the liquid helium distributor 1-9 do not contact the vacuum box 6 when passing through the vacuum box 6.

[0074] Working principle of the liquid helium supply mechanism in the embodiment: Figure 14 A simplified structure diagram of the liquid helium supply mechanism is shown in the figure, wherein related components of the liquid helium preparation and compensation mechanism are simplified, and the plate-type helium pipeline in the auxiliary gas-liquid channel 5 is cancelled, and the gas-liquid pipeline is represented by a line segment, and the arrows in the figure represent the flow directions of the cooling water or the helium, and the line segments without arrows represent that the helium or the liquid helium can flow in two directions.

[0075] Working principle of the primary refrigeration mechanism 2 in the secondary Stirling refrigeration mechanism 4: the topological diagram of the primary refrigeration mechanism 2 is shown in the figure Figure 15 , which operates according to an ideal Stirling refrigeration cycle. As shown in Figure 15 , the initial state diagram of the ideal Stirling refrigeration cycle is shown, and the feature is that the pistons in the compressor B2-1 and the expander B2-7 are both at the “top dead center”.

[0076] The ideal Stirling refrigeration cycle starts as follows.

[0077] 1. Isothermal compression process

[0078] As shown in Figure 16 , the piston in the compression chamber B2-1 moves downward to the middle (left and right, the same below), the piston in the expander B2-7 is stationary, and the helium refrigeration working medium is compressed, at this time, the gas pressure will increase, and the temperature of the gas will increase during the process of the increase of the gas pressure, and the heat will increase, assuming that all the increased heat is timely taken away by the cooling water flowing through the horizontal channel in the hot-end heat exchanger B2-2, then the temperature will not increase, so this process is called the isothermal compression process, which is only an ideal case.

[0079] 2. Isochoric compression process

[0080] As shown in Figure 17 , the piston B in the compressor B2-1 moves to the bottom dead center, and the piston A in the expander B2-7 moves downward to the middle. During this process, the volume of helium gas between the two pistons does not change, so it is called an isochoric process. During the process, the compressed helium gas passes through the regenerator A2-4, and the heat is transferred to the heat-absorbing material A2-4-2 in the regenerator A2-4, so that the temperature of the helium gas decreases, and the pressure also decreases.

[0081] 3. Isothermal expansion process

[0082] As Figure 18 shown, the piston in compressor B2-1 stays at the bottom dead center, and the piston A in expander B2-7 drops to the bottom dead center. At this time, the pressure of helium gas in the cylinder of expander B2-1 and in cold end heat exchanger B2-6 will be further reduced, and the temperature will be further lowered. This is the process of refrigerating helium gas.

[0083] 4. Isovolumic heat absorption process

[0084] As Figure 19 shown, the pistons in compressor B2-1 and expander B2-7 rise from the bottom dead center to the top dead center at the same time. The refrigerated helium gas is discharged from the cylinder of expander B2-7, and is further cooled when passing through cold end heat exchanger B2-6, and absorbs heat from regenerator B2-4 when passing through it, and continues to absorb heat when passing through hot end heat exchanger B2-2, and returns to the initial temperature when entering the compression cylinder B2-1.

[0085] So far, one Stirling cycle is completed. As a result, a part of heat is discharged from the mechanism through hot end heat exchanger B2-2, the compressor B2-1 and expander B2-7 do work, and the cold end heat exchanger B2-6 obtains cold energy.

[0086] The cycle processes 1-4 are repeated next. The temperature of helium gas passing through cold end heat exchanger B2-6 will be reduced to about 40K, and the longitudinal channels in cold end heat exchanger B2-6, which are composed of fine helium gas pipes arranged densely in horizontal and vertical directions, are also basically at the same temperature.

[0087] Working principle of secondary refrigeration mechanism 3 in two-stage Stirling refrigeration mechanism 4

[0088] Secondary refrigeration mechanism 3 also operates according to the ideal Stirling refrigeration cycle.

[0089] Figure 20is the initial state diagram of the secondary refrigeration mechanism 3 Stirling refrigeration cycle, the next Stirling refrigeration cycle is basically the same as the primary refrigeration mechanism 2 Stirling refrigeration, the difference is that, because the hot end heat exchanger of the secondary refrigeration mechanism is replaced by the cold end heat exchanger B2-6 of the primary refrigeration mechanism 2, the cold end heat exchanger is replaced by the cooler 1-4 in the liquid helium preparation mechanism 1, and the helium gas passes through the cold end heat exchanger B2-6 and the cooler 1-4, which is a horizontal passage composed of partitions. After multiple cycles, the helium gas passing through the cooler 1-4 is reduced to about 20K, and the helium gas passing through the vertical and dense helium gas pipeline in the cooler 1-4 is also cooled to the same temperature. At this time, the function of the secondary Stirling refrigeration mechanism 4 is completed. The final result is that part of the heat is removed from the mechanism through the hot end heat exchanger B2-2 in the primary refrigeration mechanism 2, the two sets of compressors and expanders do work, and the cooler 1-4 obtains more cold energy.

[0090] Working principle of liquid helium preparation mechanism 1

[0091] The preparation of liquid helium and the compensation of liquid helium in the liquid helium preparation mechanism 1 are different, which will be introduced respectively.

[0092] Working principle of liquid helium preparation:

[0093] Figure 21 is the principle diagram of liquid helium preparation, and is in the initial state at this time, the helium gas injection channel is opened, and helium gas is injected into the gas reservoir 1-2, and after filling with helium gas, the gas pressure is atmospheric pressure (atmospheric pressure), and the temperature is normal temperature (about 300K). At the same time, the piston in the air pump 1-1 (actually a compressor) is at the lower dead point.

[0094] 1) Compressor pumping.

[0095] Before the compressor pumping, open the valve A1-3-2 and close the valve B1-3-1, then the piston in the compressor rises from the lower dead point to the upper dead point, at this time, the helium gas flows from the gas reservoir 1-2 into the cavity of the compressor A1-1. Because the helium gas is not stopped, the gas pressure and temperature in the compressor cavity are the same as those in the gas reservoir 1-2.

[0096] 2) Compressor starts working.

[0097] Before the compressor starts working, open the valve A1-3-1 and close the valve B1-3-2, then the piston in the compression cavity A1-1 moves downward by a certain stroke, and the helium gas between the compressor A1-1 and the throttle valve 1-7 is compressed to a certain high pressure, at this time the temperature of the helium gas will rise. Then after two cooling processes, the helium gas in the cooler 1-4 is cooled to a large extent (to about 20K), and the helium gas in the heat exchanger 1-6 is further cooled to the required temperature (about 10K).

[0098] 3) liquefaction of helium

[0099] The throttle valve 1-7 is opened, the piston in the compressor further drops to the bottom dead center, the helium gas before the throttle valve 1-7, which has a certain high pressure and low temperature, suddenly drops from a higher pressure to normal pressure, the temperature of the helium gas will drop to a certain extent, just reaching the gas-liquid saturation temperature of helium, a part of the helium gas will liquefy and remain in the gas-liquid separator 1-8, the helium gas that has not liquefied (at the gas-liquid saturation temperature of about 4K) returns to the gas reservoir 1-2 through the heat exchanger 1-6. The low-temperature helium gas cools the heat exchanger 1-6, and the heat exchanger 1-6 cools the helium gas flowing in the opposite direction, which is the origin of the name of the heat exchanger. The temperature of the helium gas at the bottom end of the heat exchanger 1-6 is reduced to about 10K, which is a process of repeated cooling step by step, called the start-up process.

[0100] 4) Splitting of liquid helium. The liquid helium in the gas-liquid separator 1-8 is split into multiple liquid helium terminals 1-10 through the liquid helium distributor 1-9. After each liquid helium terminal 1-10 is filled with liquid helium, the process of producing liquid helium ends. If there are more liquid helium terminals 1-10 with larger volume, the process of producing liquid helium is a longer process.

[0101] Liquid helium compensation

[0102] In the liquid helium compensation stage, the channel for helium gas injection into the gas reservoir 1-2 is closed. Due to heat leakage, the liquid helium in multiple liquid helium terminals 1-10 absorbs heat and evaporates, and the evaporated helium gas overflows at the surface of the liquid helium in the gas-liquid separator 1-8. This part of helium gas also has a gas-liquid saturation temperature and returns to the gas reservoir 1-2 through the heat exchanger 1-6, becoming the source of helium gas in the liquid helium compensation stage. When the helium gas in the gas reservoir 1-2 is completely replaced by the returned helium gas, the temperature of the helium gas in the gas reservoir 1-2 is already very low, which is the main difference from the liquid helium production stage, where the temperature of the helium gas in the gas reservoir 1-2 is at room temperature. The reduction of the temperature difference (the difference between the temperature of the helium gas in the gas reservoir 1-2 and the temperature of the helium gas before throttling) improves the liquefaction efficiency in the liquid helium compensation stage.

[0103] The gas pressure in the gas reservoir A9 is monitored, and when it reaches the set value, the helium liquefaction cycle is started again to produce compensated liquid helium.

[0104] In the "1) Compressor gas extraction" stage of the helium liquefaction cycle, the temperature and pressure of the helium gas in the compressor will change slightly compared to the helium gas in the original gas reservoir 1-2, and the change depends on the ratio of the volume of the compressor chamber to the volume of the gas reservoir 1-2 and the gas pressure in the gas reservoir 1-2.

[0105] The process of the helium liquefaction cycle is the same as that in the liquid helium production process.

[0106] Several main features of the invented liquid helium production and compensation mechanism

[0107] The main features are relative to the traditional liquid helium production mechanism.

[0108] 1. The cooler 1-4 in the liquid helium production mechanism 1 is replaced by the cold end heat exchanger in the secondary refrigeration mechanism 3 (or vice versa, the cold end heat exchanger in the secondary refrigeration mechanism 3 is replaced by the cooler 1-4 in the liquid helium production mechanism 1).

[0109] The traditional liquid helium production mechanism includes a compressor, a water-cooled cooler, one or more pre-cooling mechanisms (consisting of liquid nitrogen and liquid hydrogen) in series, one or more heat exchangers in series (each additional heat exchanger requires an additional expander), a throttle valve, and a gas-liquid separator. The present application replaces the water-cooled cooler and the pre-cooling mechanism in the traditional liquid helium production mechanism with the cold end heat exchanger (i.e. the cooler 1-4) in the secondary refrigeration mechanism 3, while only retaining one heat exchanger, achieving miniaturization of the liquid helium production mechanism. There is an important reason for doing so, which is that the water-cooled cooler cannot appear in the compensation process of liquid helium. If the water-cooled cooler is still retained, the helium gas compressed and pushed by the compressor will not be cooled but will be heated when passing through the water-cooled cooler.

[0110] 2. The gas reservoir 1-2 is provided.

[0111] The gas reservoir is provided to collect the helium gas volatilized from the liquid helium terminal 1-10, and to serve as a source of helium gas for compensating the liquid helium. When the liquid helium production and compensation mechanism is working in the liquid helium compensation phase, there is no longer a need for external helium gas supply.

[0112] 3. By monitoring the pressure change in the gas reservoir 1-2, the start and termination of the liquid helium compensation process are determined, achieving automation of the liquid helium compensation. The gas pressure at the start can be higher than atmospheric pressure, which is beneficial to improving the liquefaction efficiency.

[0113] 4. To reduce the burden of the liquid helium production and compensation mechanism during the liquid helium production process (such as the production amount of liquid helium being very large), when the superconducting particle radiotherapy center is started, liquid helium can be purchased and injected into the liquid helium terminal container 1-10 at one time, and then the liquid helium production and compensation mechanism can directly enter the working state of liquid helium compensation.

Claims

1. A liquid helium supply mechanism for providing a cold source for cryogenic superconducting materials in a superconducting particle radiotherapy device, comprising a liquid helium preparation mechanism (1) for preparing liquid helium by cooling helium gas, wherein liquid helium from the liquid helium preparation mechanism (1) flows into a liquid helium terminal (1-10) for cooling the cryogenic superconducting material; characterized in that: It also includes a liquid helium compensation mechanism; the liquid helium compensation mechanism collects the helium gas vaporized by the cooling of the low-temperature superconducting material at each liquid helium terminal (1-10) and transfers the helium gas to the liquid helium preparation mechanism (1); the liquid helium preparation mechanism (1) includes a gas storage tank (1-2), a gas pump (1-1), a cooler (1-4), and a refrigerator; the gas pump (1-1) pumps the helium gas in the gas storage tank (1-2) into the cooler (1-4), the cooler (1-4) is the cold end heat exchanger of the refrigerator; the refrigerator is a two-stage Stirling refrigeration mechanism (4) including a primary refrigeration mechanism (2) and a secondary refrigeration mechanism (3); The primary refrigeration mechanism (2) includes a compressor B (2-1), a hot-end heat exchanger B (2-2), a regenerator A (2-4), a cold-end heat exchanger B (2-6), and an expander B (2-7) connected in sequence. The secondary refrigeration mechanism (3) includes a compressor C (3-1), a hot-end heat exchanger C, a regenerator B (3-2), a cold-end heat exchanger C, and an expander C (3-3) connected in sequence. The hot-end heat exchanger C is the cold-end heat exchanger B (2-6), and the cold-end heat exchanger C is the cooler (1-4); The liquid helium preparation mechanism (1) is located inside the vacuum chamber (6).

2. The liquid helium supply mechanism according to claim 1, characterized in that: The air pump (1-1) includes a cylindrical cavity A (1-1-1) with an open end and a flange. A piston (1-1-2) with a push-pull rod is inserted into the cavity A (1-1-1) from the flanged open end. The flanged open end of the cavity A (1-1-1) is connected to a pen-type linear motor (1-1-4). The push-pull rod of the piston (1-1-2) passes through the linear motor (1-1-4).

3. The liquid helium supply mechanism according to claim 2, characterized in that: The bottom of cavity A (1-1-1) is connected to a T-shaped helium pipe AA (5-1-1). One end of the horizontal pipe of the T-shaped helium pipe AA (5-1-1) is connected to the bottom of cavity A (1-1-1), and the other end is connected to the cooler (1-4) via helium channel AB (5-1-2). The extension of the vertical pipe of the T-shaped helium pipe AA (5-1-1) is connected to the gas reservoir (1-2). A valve A (1-3-1) is installed on the horizontal pipe of the T-shaped helium pipe AA (5-1-1) near the bottom of cavity A (1-1-1), and a valve B (1-3-2) is installed on the vertical pipe of the T-shaped helium pipe AA (5-1-1).

4. The liquid helium supply mechanism according to claim 3, characterized in that: The helium channel AB (5-1-2) is a plate-type helium channel, comprising a triangular upper plate (5-1-2-1) and a triangular lower plate (5-1-2-2); the triangular upper plate (5-1-2-1) and the triangular lower plate (5-1-2-2) are stacked vertically, with corresponding sides sealed to each other, and a helium inlet (5-1-2-3) is formed at their included angle to connect with the horizontal pipe of the T-shaped helium pipe AA (5-1-1). One side is connected to the cooler (1-4), and a gap (5-1-2-4) is formed between the upper triangular plate (5-1-2-1) and the lower triangular plate (5-1-2-2) to realize the connection between the helium inlet (5-1-2-3) and the cooler (1-4). Helium enters the gap (5-1-2-4) through the helium inlet (5-1-2-3), diffuses, and is discharged to the cooler (1-4) in a strip-shaped surface.

5. The liquid helium supply mechanism according to claim 1, characterized in that: The hot-end heat exchanger B (2-2), cold-end heat exchanger B (2-6), or cooler (1-4) all perform heat exchange and have the same heat exchanger structure.

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