Liquid nitrogen recondensation cooling system of high-purity germanium spectrometer

Abstract

The utility model provides a liquid nitrogen recondensation cooling system of a high-purity germanium spectrometer, which comprises a liquid nitrogen tank and a refrigerating machine, the liquid nitrogen tank is provided with a refrigerating machine mounting hole and a detector mounting hole, the periphery of the refrigerating machine mounting hole is provided with an annular groove, the annular groove is provided with an annular elastic sealing gasket, a sealing plate is fixed above the refrigerating machine mounting hole, and the sealing plate is fixed above the detector mounting hole. The sealing plate is tightly pressed on the annular elastic sealing gasket and is in tight contact with the annular elastic sealing gasket for sealing; an opening coaxial with the refrigerator mounting hole is formed in the sealing plate, an annular elastic sealing sleeve is connected to the inner wall, located at the opening, of the sealing plate, a cold finger of the refrigerator vertically penetrates through the annular elastic sealing sleeve and extends into the liquid nitrogen tank, and the cold finger of the refrigerator is in interference fit with the annular elastic sealing sleeve. According to the liquid nitrogen recondensation cooling system, the joints of the cold finger of the refrigerating machine and the cold finger of the detector and the liquid nitrogen tank are effectively sealed, and meanwhile vibration of the refrigerating machine and the cooling fan is effectively reduced through the damping piece.

Description

Technical Field

[0001] The utility model relates to the technical field of cooling a detector of a high-purity germanium spectrometer, in particular to a liquid nitrogen condensation cooling system of the high-purity germanium spectrometer. Background Art

[0002] The liquid nitrogen recondensation refrigeration system is a hybrid refrigerator that combines conventional liquid nitrogen with an electric refrigerator. It is used to continuously cool the detectors of high-purity germanium spectrometers. During operation, the liquid nitrogen stored in the liquid nitrogen tank continuously evaporates into nitrogen gas due to factors such as the insertion of the detector. The liquid nitrogen recondensation refrigeration system utilizes a Stirling refrigerator as its core component, keeping the refrigerator's cold end temperature lower than that of liquid nitrogen. This condenses the gaseous nitrogen in the tank into liquid nitrogen, enabling liquid nitrogen recycling. Compared to electric refrigerators, liquid nitrogen recondensation refrigeration uses liquid nitrogen as the medium, eliminating direct contact between the detector and the refrigerator, significantly reducing the impact of vibration on detector performance. It also overcomes the major drawback of electric refrigerators, which lose their cooling capacity during power failures, ensuring that the detector remains at a low temperature even in a power outage, allowing for rapid operation upon power restoration. Compared to liquid nitrogen refrigeration, liquid nitrogen recondensation refrigeration eliminates the need for frequent liquid nitrogen refills while maintaining reliable performance, ensuring long-term detector operation at a low temperature and saving on liquid nitrogen materials and labor costs.

[0003] However, the refrigerator, the core component of the liquid nitrogen condensation refrigeration system, generates vibrations during operation. This is determined by the refrigerator's operating principle: the greater the power, the greater the vibration. Furthermore, the cooling fan in the liquid nitrogen condensation refrigeration unit also generates vibrations. These vibrations cause the liquid nitrogen condensation refrigeration system to vibrate, which is then transmitted to the detector. The detector of the high-purity germanium spectrometer connected to the liquid nitrogen condensation refrigeration system is a precision device and needs to be minimized to avoid vibrations, as vibrations can reduce detector resolution and affect performance. Therefore, reducing vibrations in the liquid nitrogen condensation refrigeration system can effectively improve detector performance. Furthermore, the sealing quality of the liquid nitrogen condensation refrigeration unit directly determines the lifespan of a single refill of liquid nitrogen. Utility Model Content

[0004] In response to the deficiencies in the prior art, the utility model provides a liquid nitrogen condensation cooling system for a high-purity germanium spectrometer. The liquid nitrogen condensation cooling system effectively seals the connection between the cold fingers of the refrigerator and the detector and the liquid nitrogen tank, thereby extending the use time of a single liquid nitrogen refill. The sealing points of the cold fingers of the refrigerator and the detector can also reduce vibration. At the same time, the shock-absorbing parts effectively reduce the vibration of the refrigerator and the cooling fan, thereby preventing the performance of the detector from being affected by vibration.

[0005] The technical solutions adopted to achieve the above-mentioned purpose of the utility model are:

[0006] A liquid nitrogen condensation cooling system for a high-purity germanium spectrometer comprises a liquid nitrogen tank and a refrigerator. The liquid nitrogen tank is provided with a refrigerator mounting hole and a detector mounting hole. The cold finger of the refrigerator extends from the refrigerator mounting hole into the liquid nitrogen tank for cooling. The cold finger of the detector of the high-purity germanium spectrometer extends from the detector mounting hole into the liquid nitrogen tank for cooling. The refrigerator mounting hole is provided with an annular groove around it, and an annular elastic sealing gasket is installed on the annular groove. A sealing plate is fixed above the refrigerator mounting hole, and the sealing plate is pressed against the annular elastic sealing gasket and is in close contact and sealing with the annular elastic sealing gasket; the sealing plate is provided with an opening coaxial with the refrigerator mounting hole, and an annular elastic sealing sleeve is connected to the inner wall of the sealing plate located at the opening. The cold finger of the refrigerator vertically passes through the annular elastic sealing sleeve and extends into the liquid nitrogen tank, and the cold finger of the refrigerator is interference fit with the annular elastic sealing sleeve.

[0007] The cross section of the annular elastic sealing sleeve is U-shaped, and the U-shaped opening is arranged upward.

[0008] The sealing plate is made of metal material, and the sealing plate and the annular elastic sealing sleeve are integrally injection-molded.

[0009] The inner diameter of the annular elastic sealing sleeve is 0.5 mm smaller than the diameter of the cold finger of the refrigerator in contact with the annular elastic sealing sleeve.

[0010] The annular elastic sealing gasket is higher than the upper surface of the annular groove.

[0011] A connecting flange is tightly fitted on the detector mounting hole, and the connecting flange has a T-shaped tubular structure as a whole; a plurality of elastic sealing rings are fitted on the cold finger of the detector, and the cold finger of the detector extends vertically into the connecting flange and enters the liquid nitrogen tank, and the elastic sealing rings are in close contact with the inner wall of the connecting flange.

[0012] A gland is sleeved on the cold finger of the detector, and the gland is located on the upper part of all elastic sealing rings. The gland is connected to the upper part of the connecting flange through threads, and the gland is pressed tightly on the uppermost elastic sealing ring.

[0013] An annular limiting platform is connected to the inner wall of the bottom end of the connecting flange, and the annular limiting platform is located below all elastic sealing rings. The inner diameter of the annular limiting platform is larger than the outer diameter of the cold finger of the detector, and the inner diameter of the annular limiting platform is smaller than the outer diameter of the elastic sealing ring.

[0014] Shock absorbers are connected to the four corners of the bottom of the refrigerator, and the shock absorbers are fixedly installed on the liquid nitrogen tank; the shock absorbers include a central cylindrical buffer body and studs connected to the upper and lower ends of the cylindrical buffer body.

[0015] A heat sink is installed at the bottom of the refrigerator, and a cooling fan is installed on one side of the refrigerator. Except for the bottom and the side surface on which the cooling fan is installed, a wrapping shell is installed on the other sides and the top surface of the refrigerator, and an air duct is left between the wrapping shell and the heat sink, and the cooling fan is located at the outlet of the air duct.

[0016] Compared with the prior art, the technical solution provided by the present invention has the following advantages: (1) The liquid nitrogen condensation cooling system of the high-purity germanium spectrometer provided in the present invention seals the refrigerator and the liquid nitrogen tank by installing an annular elastic sealing gasket, a sealing plate and an annular elastic sealing sleeve between the cold finger of the refrigerator and the liquid nitrogen tank, thereby achieving a good sealing effect, preventing the liquid nitrogen from escaping from the gap between the refrigerator and the liquid nitrogen tank after volatilization into nitrogen gas, and improving the use time after one filling of liquid nitrogen.

[0017] (2) In the present invention, an elastic sealing ring and a pressure cover are installed between the cold finger of the detector and the liquid nitrogen tank to ensure the sealing effect of the detector and the liquid nitrogen tank, thereby further improving the use time after one filling of liquid nitrogen.

[0018] (3) In the present invention, the cooling fan and the refrigerator are integrated into one design, and a shock-absorbing member is installed between the refrigerator and the liquid nitrogen tank, which can eliminate the vibration when the refrigerator and the cooling fan are working, thereby avoiding affecting the performance of the detector. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic diagram of the structure of the liquid nitrogen condensation cooling system of the high-purity germanium spectrometer provided by the present invention;

[0020] Figure 2 This is a schematic diagram of the connection between the cold finger of the refrigerator and the liquid nitrogen tank in the present invention;

[0021] Figure 3 This is a schematic diagram of the connection between the cold finger of the detector and the liquid nitrogen tank in the present invention;

[0022] Figure 4 This is a schematic diagram of the connection between the refrigerator and the heat sink in the present invention;

[0023] Figure 5 This is a schematic diagram of the connection between the refrigerator and the cooling fan in the present invention;

[0024] Figure 6 This is a schematic structural diagram of the shock-absorbing component in the utility model;

[0025] In the figure: 1-liquid nitrogen tank, 2-refrigeration machine, 3-detector, 4-annular groove, 5-annular elastic sealing gasket, 6-sealing plate, 7-annular elastic sealing sleeve, 8-connecting flange, 9-elastic sealing ring, 10-pressure cover, 11-annular limiting platform, 12-heat sink, 13-cooling fan, 14-wrapping shell, 15-shock absorber, 151-cylindrical buffer body, 152-stud. DETAILED DESCRIPTION

[0026] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] The liquid nitrogen condensation cooling system of the high purity germanium spectrometer provided in this embodiment is as follows: Figure 1 As shown, the liquid nitrogen condensation cooling system includes a liquid nitrogen tank 1 and a refrigerator 2. The liquid nitrogen tank is provided with a refrigerator mounting hole and a detector mounting hole. The cold finger of the refrigerator extends from the refrigerator mounting hole into the liquid nitrogen tank for cooling. The cold finger of the detector 3 of the high-purity germanium spectrometer extends from the detector mounting hole into the liquid nitrogen tank for cooling. During the cooling process, the liquid nitrogen continuously evaporates into nitrogen gas. When the gas pressure in the liquid nitrogen tank increases to a certain value, the refrigerator works. The temperature of the cold finger of the refrigerator is lower than the condensation temperature of the liquid nitrogen, and the nitrogen gas is continuously condensed to achieve condensation cooling of the liquid nitrogen.

[0028] In this embodiment, an annular groove 4 is provided around the refrigerator mounting hole on the liquid nitrogen tank, and an annular elastic sealing gasket 5 is installed on the annular groove. Figure 2 As shown. Specifically, the annular elastic sealing gasket is made of elastic materials such as rubber, silicone, polyurethane, etc. A sealing plate 6 is fixed above the refrigerator mounting hole, and the sealing plate is pressed on the annular elastic sealing gasket and is in close contact and sealing with the annular elastic sealing gasket. The annular elastic sealing gasket is higher than the upper surface of the annular groove to ensure that the sealing plate and the annular elastic sealing gasket are pressed tightly. Specifically, the four corners of the sealing plate are fixedly connected to the liquid nitrogen tank by bolts. An opening coaxial with the refrigerator mounting hole is provided on the sealing plate, and an annular elastic sealing sleeve 7 is connected to the inner wall of the sealing plate located at the opening. The cold finger of the refrigerator passes vertically through the annular elastic sealing sleeve and extends into the liquid nitrogen tank, and the cold finger of the refrigerator is interference fit with the annular elastic sealing sleeve. Specifically, the cold finger of the refrigerator is a cylindrical structure, the opening on the sealing plate is circular, and the inner diameter of the annular elastic sealing sleeve is about 0.5 mm smaller than the diameter of the cold finger of the refrigerator in contact with it, achieving an interference fit effect, so that the cold finger of the refrigerator and the annular elastic sealing sleeve are in close contact and sealing on the vertical plane, while the sealing plate and the annular elastic sealing gasket are in close contact and sealing on the horizontal plane, thereby ensuring a good sealing effect between the refrigerator and the liquid nitrogen tank.

[0029] In this embodiment, an annular stop step is provided on the bottom inner wall of the sealing plate opening. The annular elastic sealing sleeve is mounted on the annular stop step and tightly fits against the inner wall of the sealing plate opening. Preferably, the annular elastic sealing sleeve has a U-shaped cross-section, with the U-shaped portion facing upward. This prevents the annular elastic sealing sleeve from curling under the pressure of the refrigerator's cold fingers and allows it to automatically rebound to its proper shape. Furthermore, the sealing plate is made of metal, and the annular elastic sealing sleeve is made of an elastic material such as rubber, silicone, or polyurethane. The sealing plate and annular elastic sealing sleeve are integrally injection molded, ensuring strong bonding and a secure seal. Because the refrigerator's cold fingers experience slight oscillation, the interference fit of this design effectively seals the cold fingers. The U-shaped structure also provides suitable horizontal strength, preventing the contact area from sagging and leaking, while maximizing the shock absorption effect.

[0030] In this embodiment, a connecting flange 8 is tightly attached to the detector mounting hole, and the connecting flange is a T-shaped tubular structure as a whole. Figure 3As shown. Specifically, the upper part of the connecting flange is flatly fixed to the liquid nitrogen tank, the lower part of the connecting flange extends into the detector mounting hole, and the lower outer wall of the connecting flange is tightly against the detector mounting hole. A plurality of elastic sealing rings 9 are sleeved on the cold finger of the detector, and the cold finger of the detector extends vertically into the connecting flange and enters the liquid nitrogen tank, and the elastic sealing ring is in close contact with the inner wall of the connecting flange. Specifically, the cross-sectional diameter of the elastic sealing ring is 5mm, and the elastic sealing ring has an interference fit with the cold finger of the detector, with an interference fit of 2mm; the elastic sealing ring has an interference fit with the connecting flange, and the interference size is 0.5mm. Preferably, five elastic sealing rings are sleeved on the cold finger of the detector, and the elastic sealing rings are made of elastic materials such as rubber, silicone, and polyurethane to ensure the formation of a multi-layer sealing effect, form a surface seal, and enhance the reliability of the seal; it can also maintain the stability of the detector, so that the detector is not easy to shake. The cold finger of the detector is covered with a gland 10, and the gland is located at the top of all elastic sealing rings. The gland is connected to the upper part of the connecting flange by threads, and the gland is pressed against the elastic sealing ring on the top layer to further ensure the sealing effect. Specifically, an external thread is provided on the upper outer wall of the connecting flange, and an internal thread matching the external thread is provided on the gland, so that the gland is fixedly connected to the connecting flange by threads. Furthermore, the diameter of the hole on the gland is larger than the outer diameter of the cold finger of the detector, but smaller than the outer diameter of the elastic sealing ring. An annular limiting platform 11 is connected to the inner wall of the bottom end of the connecting flange, and the annular limiting platform is located at the bottom of all elastic sealing rings. The inner diameter of the annular limiting platform is larger than the outer diameter of the cold finger of the detector, ensuring that the cold finger of the detector can be inserted into the liquid nitrogen tank. The inner diameter of the annular limiting platform is smaller than the outer diameter of the elastic sealing ring, preventing the annular silicone ring from being squeezed downward and falling when the cold finger of the detector is inserted, thereby playing a limiting role. The cold finger of the detector is installed vertically, and the elastic sealing ring realizes the insertion of the cold finger of the detector by rolling and squeezing, while ensuring the sealing of the cold finger of the detector. The pressure cover presses on the elastic sealing ring to prevent the elastic sealing ring from popping out due to the high internal air pressure, thereby enhancing the sealing performance.

[0031] In this embodiment, a heat sink 12 is installed at the bottom of the refrigerator. Figure 4 A cooling fan 13 is installed on one side of the refrigerator. Figure 5 As shown, except for the bottom and one side surface where the cooling fan is installed, the other side surfaces and the top surface of the refrigerator are all installed with a wrapping shell 14, and an air duct is left between the wrapping shell and the heat sink, and the cooling fan is located at the outlet of the air duct. Specifically, the cooling fan is fixed to the wrapping shell by screws, and the blowing direction of the cooling fan is outward, so that the air flows from the heat sink into the air duct and flows out of the air duct from the air duct outlet. In this embodiment, shock absorbers 15 are connected to the four corners of the bottom of the refrigerator, and the shock absorbers are fixedly installed on the liquid nitrogen tank; the shock absorbers include a cylindrical buffer body 151 in the middle and studs 152 connected to the upper and lower ends of the cylindrical buffer body, as shown in FIG. Figure 6Specifically, studs at the upper and lower ends are fixedly connected to the refrigerator and liquid nitrogen tank, respectively. The cylindrical buffer body is made of materials such as silicone, silica gel, or rubber. Furthermore, stainless steel discs are fixedly connected to the upper and lower ends of the cylindrical buffer body, each of which is connected to a stud. This transmits vibrations to the cylindrical buffer body, reducing vibrations from the cooling fan and refrigerator itself during operation, thereby preventing any impact on detector performance.

Claims

1. A liquid nitrogen condensation cooling system for a high-purity germanium spectrometer, comprising a liquid nitrogen tank and a refrigerator, wherein the liquid nitrogen tank is provided with a refrigerator mounting hole and a detector mounting hole, wherein the cold finger of the refrigerator extends from the refrigerator mounting hole into the liquid nitrogen tank for cooling, and the cold finger of the detector of the high-purity germanium spectrometer extends from the detector mounting hole into the liquid nitrogen tank for cooling, characterized in that: An annular groove is provided around the refrigerator mounting hole, an annular elastic sealing gasket is installed on the annular groove, a sealing plate is fixed above the refrigerator mounting hole, and the sealing plate is pressed on the annular elastic sealing gasket and is in close contact and sealing with the annular elastic sealing gasket; an opening coaxial with the refrigerator mounting hole is provided on the sealing plate, an annular elastic sealing sleeve is connected to the inner wall of the sealing plate at the opening, the cold finger of the refrigerator vertically passes through the annular elastic sealing sleeve and extends into the liquid nitrogen tank, and the cold finger of the refrigerator is interference fit with the annular elastic sealing sleeve.

2. The liquid nitrogen condensation cooling system for a high-purity germanium spectrometer according to claim 1, characterized in that: The cross section of the annular elastic sealing sleeve is U-shaped, and the U-shaped opening is arranged upward.

3. The liquid nitrogen condensation cooling system for a high-purity germanium spectrometer according to claim 1, characterized in that: The sealing plate is made of metal material, and the sealing plate and the annular elastic sealing sleeve are integrally injection-molded.

4. The liquid nitrogen condensation cooling system for a high-purity germanium spectrometer according to claim 1, characterized in that: The inner diameter of the annular elastic sealing sleeve is 0.5 mm smaller than the diameter of the cold finger of the refrigerator in contact with the annular elastic sealing sleeve.

5. The liquid nitrogen condensation cooling system for a high-purity germanium spectrometer according to claim 1, characterized in that: The annular elastic sealing gasket is higher than the upper surface of the annular groove.

6. The liquid nitrogen condensation cooling system for a high-purity germanium spectrometer according to claim 1, characterized in that: A connecting flange is tightly fitted on the detector mounting hole, and the connecting flange has a T-shaped tubular structure as a whole; a plurality of elastic sealing rings are fitted on the cold finger of the detector, and the cold finger of the detector extends vertically into the connecting flange and enters the liquid nitrogen tank, and the elastic sealing rings are in close contact with the inner wall of the connecting flange.

7. The liquid nitrogen condensation cooling system for the high-purity germanium spectrometer according to claim 6, characterized in that: A gland is sleeved on the cold finger of the detector, and the gland is located on the upper part of all elastic sealing rings. The gland is connected to the upper part of the connecting flange through threads, and the gland is pressed tightly on the uppermost elastic sealing ring.

8. The liquid nitrogen condensation cooling system for a high-purity germanium spectrometer according to claim 6, characterized in that: An annular limiting platform is connected to the inner wall of the bottom end of the connecting flange, and the annular limiting platform is located below all elastic sealing rings. The inner diameter of the annular limiting platform is larger than the outer diameter of the cold finger of the detector, and the inner diameter of the annular limiting platform is smaller than the outer diameter of the elastic sealing ring.

9. The liquid nitrogen condensation cooling system for a high-purity germanium spectrometer according to claim 1, characterized in that: Shock absorbers are connected to the four corners of the bottom of the refrigerator, and the shock absorbers are fixedly installed on the liquid nitrogen tank; the shock absorbers include a central cylindrical buffer body and studs connected to the upper and lower ends of the cylindrical buffer body.

10. The liquid nitrogen condensation cooling system for a high-purity germanium spectrometer according to claim 1, characterized in that: A heat sink is installed at the bottom of the refrigerator, and a cooling fan is installed on one side of the refrigerator. Except for the bottom and the side surface on which the cooling fan is installed, a wrapping shell is installed on the other sides and the top surface of the refrigerator, and an air duct is left between the wrapping shell and the heat sink, and the cooling fan is located at the outlet of the air duct.

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