Cooling circulation system for ultrahigh-field radio frequency coil

Abstract

The utility model discloses a cooling circulation system for an ultrahigh field radio frequency coil, which belongs to the technical field of superconducting magnets and comprises a cooling mechanism, the cooling mechanism is mounted on a support and comprises a vacuum cavity and a refrigerating machine, the refrigerating machine is arranged at the top of the vacuum cavity and comprises a first-stage cold head and a second-stage cold head, and the first-stage cold head is connected with the second-stage cold head. The first-stage cold head and the second-stage cold head are arranged in a cavity in the vacuum cavity; the side face of the cavity is connected with a helium supplementing opening, the helium supplementing opening is formed in the top of the vacuum cavity, and the bottom of the cavity communicates with a liquid helium conveying pipe. A nitrogen cavity is further formed in the vacuum cavity and connected with the first-stage cold head through flexible connection, and the bottom of the nitrogen cavity communicates with a liquid nitrogen conveying pipe. The cooling circulation system for the ultrahigh-field radio frequency coil can reduce loss of liquid nitrogen and liquid helium and can avoid influence of noise of equipment such as a refrigerating machine compressor on imaging.

Description

Technical Field

[0001] The utility model relates to the technical field of superconducting magnets, in particular to a cooling circulation system for an ultra-high field radio frequency coil. Background Art

[0002] Magnetic resonance imaging (MRI) is one of the most advanced and accurate diagnostic methods in the field of modern medical imaging. The RF receiving coil in the RF system is used to receive pulse signals and generate images after processing. Its performance is directly related to the image quality. Therefore, in order to improve the signal-to-noise ratio of the RF receiving coil, RF coils made of superconducting materials can improve the image quality of MRI by more than ten times.

[0003] The superconducting material used to make high-temperature superconducting radio frequency coils has a superconducting temperature of 40-90K and must remain stable at low temperatures to maintain its superconducting properties. Current cryogenic systems typically maintain these low temperatures by evaporating liquid nitrogen or helium. These cryogenic systems typically include a liquid nitrogen dewar in close contact with the coil, containing a specific volume of liquid nitrogen to maintain a stable low temperature for the coil's operating time. To ensure the coil's continuous operation for extended periods, the dewar's size must be increased, increasing its size and weight, making it difficult to operate. Alternatively, a cryogenic refrigerator can be used to liquefy the evaporated nitrogen and helium and then pressurize them back into the dewar, reducing losses and lowering costs.

[0004] For example, our company's previous patent CN 212542070 U discloses an improved condenser for liquid helium volatile superconducting magnets without liquid helium volatilization. Specifically, it includes a liquid helium volatile superconducting magnet and a condenser arranged on the liquid helium volatile superconducting magnet. The liquid helium in the liquid helium cavity is heated to become helium gas, which evaporates upward into the liquid helium condensing chamber of the condenser. The cooling capacity generated by the secondary cold head causes the helium gas to be converted back into liquid helium and return to the liquid helium cavity. The liquid nitrogen in the liquid nitrogen cavity is converted into nitrogen gas, which evaporates upward into the liquid nitrogen condensing chamber of the condenser. The cooling capacity generated by the primary cold head is transferred to the liquid nitrogen condensing chamber via a cold conduction belt. The nitrogen gas inside is converted into liquid nitrogen and flows back into the liquid nitrogen cavity through a liquid nitrogen reflux chamber pipe.

[0005] In the above design, since the condenser is located on the upper part of the superconducting magnet, when the radio frequency coil receives the signal, the noise generated by the vibration of the refrigerator and compressor will affect the image quality, so further improvement is needed. Utility Model Content

[0006] The technical problem to be solved by the utility model is to design a cooling circulation system for an ultra-high field radio frequency coil which can reduce the loss of liquid nitrogen and liquid helium and avoid the influence of noise of equipment such as refrigerator compressor on imaging.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions: A cooling circulation system for an ultra-high field radio frequency coil, comprising a cooling mechanism, the cooling mechanism being mounted on a bracket, the cooling mechanism comprising a vacuum chamber and a refrigerator, the refrigerator being disposed at the top of the vacuum chamber, the refrigerator comprising a primary cold head and a secondary cold head, the primary cold head and the secondary cold head being disposed in a cavity inside the vacuum chamber;

[0008] The side of the cavity is connected to a helium supply port, which is provided at the top of the vacuum chamber. The bottom of the cavity is connected to a liquid helium transmission tube, which passes through an outlet at the bottom of the vacuum chamber and exits the vacuum chamber. The end of the liquid helium transmission tube is connected to a connection end of a high-temperature superconducting radio frequency coil.

[0009] A nitrogen chamber is also provided in the vacuum chamber, and the nitrogen chamber is connected to the first-level cold head through a flexible connection. The bottom of the nitrogen chamber is connected to the liquid nitrogen transmission pipe, and the liquid nitrogen transmission pipe passes through the outlet and extends outward to the end of the liquid helium transmission pipe, and the liquid nitrogen transmission pipe and the liquid helium transmission pipe are wrapped together in a hose.

[0010] Furthermore, the upper portion of the nitrogen chamber is connected to a nitrogen supply port, and the nitrogen supply port is arranged at the top of the vacuum chamber.

[0011] Furthermore, a vacuum exhaust port is provided on the top of the vacuum chamber.

[0012] Furthermore, a heat exchanger is provided at the lower portion of the secondary cold head.

[0013] Furthermore, the heat exchanger includes a secondary cold head contact surface, heat exchange fins and screw mounting holes.

[0014] Furthermore, the flexible connection is arched, with bolt holes provided at both ends.

[0015] Preferably, the flexible connection is a copper sheet.

[0016] Preferably, the hose is a corrugated tube. Beneficial effects

[0017] The present application separates the refrigerator and compressor from the high-temperature superconducting radio frequency coil by providing a bracket, so that the vibration of the refrigerator and compressor will not affect the imaging of the high-temperature superconducting radio frequency coil.

[0018] After adding a certain amount of nitrogen and helium into this cooling cycle system, they are liquefied by the refrigerator and naturally convected to the high-temperature superconducting radio frequency coil. After about 12 hours of cyclic refrigeration, the temperature of the radio frequency coil can be lower than 10K, which is far lower than the temperature of the required superconducting state, and can ensure continuous and stable operation.

[0019] The cooling circulation system of the present application does not require the use of liquid nitrogen and liquid helium, simplifies the operating process, and avoids the risk of frostbite that may occur when using liquid nitrogen and liquid helium. Liquid nitrogen is very expensive, and the use of helium can effectively reduce costs and achieve zero consumption through the self-circulation of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the structure of the cooling circulation system of the utility model.

[0021] Figure 2 This is a schematic structural diagram of the heat exchanger of the present utility model.

[0022] Figure 3 This is a structural diagram of the soft connection of the utility model.

[0023] Among them, 1-high-temperature superconducting RF coil connection end, 2-bellows, 3-liquid helium transmission tube, 4-secondary cold head, 5-primary cold head, 6-cavity, 7-refrigeration machine, 8-nitrogen cavity, 9-vacuum exhaust port, 10-vacuum cavity, 11-flexible connection, 111-bolt hole, 12-liquid nitrogen transmission tube, 13-bracket, 14-heat exchanger, 141-secondary cold head contact surface, 142-heat exchange plate, 143-screw mounting hole, 15-export. DETAILED DESCRIPTION

[0024] In order to enhance the understanding of the present invention, the present invention will be described in detail below with reference to embodiments and drawings. The embodiments are only used to explain the present invention and do not limit the scope of protection of the present invention.

[0025] like Figure 1 The figure shows a cooling circulation system for an ultra-high field radio frequency coil. It includes a cooling mechanism mounted on a bracket 13. The bracket 13 can be adjusted to a desired height based on the actual orientation of the magnetic resonance magnet opening. The cooling mechanism comprises a vacuum chamber 10 and a refrigerator 7. A vacuum pump 9 is provided on the outer wall of the vacuum chamber 10, which can be located at the top or bottom of the chamber. This pump is connected to an external vacuum pump to maintain the desired negative pressure (<10-4 Pa) in the chamber.

[0026] The refrigerator 7 is installed on the top of the vacuum chamber 10 . The refrigerator 7 includes a primary cold head 5 and a secondary cold head 4 . The primary cold head 5 and the secondary cold head 4 are installed in a cavity 6 inside the vacuum chamber 10 .

[0027] The side of cavity 6 is connected to a helium refill port 61, which is located at the top of vacuum chamber 10 and connected to cavity 6 via a vacuum bellows. The bottom of cavity 6 is connected to a liquid helium transfer tube 3, which exits vacuum chamber 10 through an outlet 15 at the bottom of vacuum chamber 10 and is terminated at a high-temperature superconducting radio frequency coil connection terminal 1.

[0028] A nitrogen chamber 8 is also provided within the vacuum chamber 10. This chamber is connected to the primary cold head 5 via a flexible connector 11. The bottom of the chamber 8 is connected to a liquid nitrogen transmission tube 12. This liquid nitrogen transmission tube 12 extends through an outlet 15 and outward to the end of the liquid helium transmission tube 3. Both the liquid nitrogen transmission tube 12 and the liquid helium transmission tube 3 are enclosed within a flexible tube 2. The flexible tube 2 may be a corrugated tube, which facilitates bending and reduces vibration and noise.

[0029] The upper portion of the nitrogen chamber 8 is connected to a nitrogen supply port 81 , which is provided at the top of the vacuum chamber 10 .

[0030] According to a preferred embodiment of the present invention, a heat exchanger 14 is installed at the lower portion of the secondary cold head 4 to improve the heat exchange efficiency of the helium.

[0031] like Figure 2 As shown, the heat exchanger 14 includes a secondary cold head contact surface 141, a heat exchange plate 142 and a screw mounting hole 143, wherein the heat exchange plate 142 is a copper plate, and the screw mounting hole 143 is matched with the secondary cold head end surface mounting hole.

[0032] According to a preferred embodiment of the present invention, the flexible connection 11 is an arched copper sheet with bolt holes 111 provided at both ends. The bolt hole 111 at one end is connected to the heat conducting ring on the first-stage cold head, and the other end is connected to the nitrogen chamber 8.

[0033] When the cooling cycle system is used, the vacuum chamber 10 is first evacuated, and the refrigerator 7 is running for refrigeration. When the internal environment is stable, nitrogen is added through the nitrogen replenishment port 81. The nitrogen chamber 8 is connected to the first-stage cold head 5 of the refrigerator 7 through the cooling belt 11. The nitrogen is liquefied and naturally convects to the end through the liquid nitrogen transmission pipe 12, cooling the area around the liquid helium transmission pipe 3 to achieve thermal separation between 300K and 4K.

[0034] Helium is added through the helium supply port 61, and the secondary cold head 4 of the refrigerator cools the helium, liquefying the helium and flowing naturally through the liquid helium transmission tube 3 to the terminal high-temperature superconducting radio frequency coil connection end 1. The high-temperature superconducting radio frequency coil will continuously vaporize the liquid helium during the cooling process, and the vaporized helium will then be liquefied through the secondary cold head 4, and the cycle will be repeated until the temperature required for the superconducting state of the high-temperature superconducting material is reached.

[0035] The embodiments disclosed in the present invention are preferred embodiments, but are not limited thereto. Ordinary technicians in this field can easily understand the spirit of the present invention based on the above embodiments and make different extensions and changes. As long as they do not deviate from the spirit of the present invention, they are all within the scope of protection of the present invention.

Claims

1. A cooling circulation system for an ultra-high field radio frequency coil, comprising a cooling mechanism, characterized in that: The cooling mechanism is mounted on a bracket (13), and comprises a vacuum chamber (10) and a refrigerator (7), wherein the refrigerator (7) is arranged on the top of the vacuum chamber (10), and the refrigerator (7) comprises a primary cold head (5) and a secondary cold head (4), wherein the primary cold head (5) and the secondary cold head (4) are arranged in a cavity (6) inside the vacuum chamber (10); The side of the cavity (6) is connected to a helium supply port (61), and the helium supply port (61) is arranged at the top of the vacuum chamber (10). The bottom of the cavity (6) is connected to a liquid helium transmission tube (3), and the liquid helium transmission tube (3) passes through the vacuum chamber (10) through an outlet (15) at the bottom of the vacuum chamber (10), and the end of the liquid helium transmission tube (3) is connected to a high-temperature superconducting radio frequency coil connection end (1); A nitrogen chamber (8) is further provided in the vacuum chamber (10), and the nitrogen chamber (8) is connected to the first-stage cold head (5) via a soft connection (11). The bottom of the nitrogen chamber (8) is connected to a liquid nitrogen transmission pipe (12), and the liquid nitrogen transmission pipe (12) passes through an outlet (15) and extends outward to the end of the liquid helium transmission pipe (3), and the liquid nitrogen transmission pipe (12) and the liquid helium transmission pipe (3) are wrapped together in the hose (2).

2. The cooling circulation system for ultra-high field radio frequency coils according to claim 1, characterized in that: The upper portion of the nitrogen chamber (8) is connected to a nitrogen supply port (81), and the nitrogen supply port (81) is arranged at the top of the vacuum chamber (10).

3. The cooling circulation system for an ultra-high field radio frequency coil according to claim 1, characterized in that: A vacuum exhaust port (9) is provided at the top of the vacuum chamber (10).

4. The cooling circulation system for an ultra-high field radio frequency coil according to claim 1, characterized in that: A heat exchanger (14) is provided at the lower portion of the secondary cold head (4).

5. The cooling circulation system for ultra-high field radio frequency coils according to claim 4, characterized in that: The heat exchanger (14) comprises a secondary cold head contact surface (141), a heat exchange plate (142) and a screw mounting hole (143).

6. The cooling circulation system for an ultra-high field radio frequency coil according to claim 1, characterized in that: The flexible connection (11) is arched, with bolt holes (111) provided at both ends.

7. The cooling circulation system for an ultra-high field radio frequency coil according to claim 6, characterized in that: The flexible connection (11) is a copper sheet.

8. The cooling circulation system for an ultra-high field radio frequency coil according to claim 6, characterized in that: The hose (2) is a corrugated tube.

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