Device for testing tightness of units of vacuum cryostat housings of matrix photodetector devices

Abstract

FIELD: testing.SUBSTANCE: invention relates to devices for testing the tightness of products and can be used to test the tightness of units of vacuum cryostatic housings (VCH) of matrix photodetector devices, in particular sleeve holders. The device for testing the tightness of the VKK units of photodetectors includes a helium mass-spectrometric leak detector 12 with a vacuum device, a sleeve 3, a clamping clamp 6, tightened with screws, a housing 2 with a filling valve, a second clamping clamp 14, tightened with screws, and high-pressure helium. The sleeve 3 is installed on the bell 11 of the leak detector 12 and is hermetically connected on one side with the bell of the leak detector through a flange with an external conical surface and a sealing ring using a clamp 6, and on the other side with the body through a similar flange with an external conical surface and a sealing ring using a second clamp 14. The tested item 1 is placed between the flange and the housing so that one end of the tested item contacts the housing 2 through the sealing ring 4, and the second end of the tested item contacts the sleeve 3 through the sealing ring 5. The housing 2 includes a filling valve, and the common internal cavity of the housing and the tested item is filled with helium under increased pressure.EFFECT: increase in the sensitivity and reliability of leak testing by bringing the testing conditions closer to the conditions and specifics of the operation of the VCH assemblies when using a compact control device.3 cl, 1 dwg

Description

[0001] The invention relates to devices for testing the tightness of products and can be used to test the tightness of units of vacuum cryostatic housings (VCH) of matrix photodetector devices, in particular, sleeve holders.

[0002] The peculiarity of the holder sleeve is that, on the one hand, it is a functional element of a gas microcryogenic machine operating with high-pressure helium filling (up to 50 kgf / cm 2 and, on the other hand, part of the vacuum housing (cryostat) of the photodetector. Thus, the holder sleeve separates two working environments—high-pressure helium and vacuum. Considering that the parts of the holder sleeve are typically connected by soldering or welding, checking the tightness of this assembly is extremely important to ensure its proper functioning.

[0003] In the book by E.P. Sheshin “Vacuum Technologies”, Dolgoprudny, Intellect Publishing House, 2009, pp. 261-264, several devices for testing the tightness of products are described.

[0004] A device is known for testing the tightness of products using a helium mass-spectrometric leak detector by the blowing method (see the mentioned source - pp. 261-262), including a helium mass-spectrometric leak detector with a pumping (vacuuming) device, hermetically connected to the product being tested, and a helium cylinder to which a blower is connected.

[0005] The disadvantages of this device are the long response time and low reliability due to the inconsistency of the test conditions with the specific operation of the VKK units, which operate under vacuum conditions with one surface, while the other is exposed to high-pressure helium.

[0006] A device is known for testing the tightness of products using a helium mass-spectrometric leak detector using a probe method (ibid. - p. 263), including a helium mass-spectrometric leak detector with a pumping (vacuum) device, a probe hermetically connected to the leak detector, and a helium cylinder hermetically connected to the product being tested.

[0007] The disadvantages of such a device are limited sensitivity (no better than 10 -7 atm.cm 2 / c) and low reliability due to the discrepancy between the testing conditions and the specific operation of the VKK units, which operate under vacuum conditions with one surface, while the other is exposed to high-pressure helium.

[0008] A device is known for testing the tightness of products using a helium mass-spectrometric leak detector using the reverse current method (ibid. - pp. 263-265), including a helium cylinder and a chamber hermetically connected to the helium cylinder, in which the product being tested can be placed, a helium mass-spectrometric leak detector with a pumping (vacuuming) device, hermetically connected to the vacuum chamber, in which the product being tested can be placed.

[0009] The disadvantages of such a device are its limited application (it can only be used for products that can be completely sealed (pressurized)) and low reliability due to the inconsistency of the testing conditions with the specific operation of the VKK units, which operate under vacuum conditions with one surface, while the other is exposed to high-pressure helium.

[0010] The closest analogue of the proposed device is a device for checking the tightness of products using a helium mass-spectrometric leak detector using the pressure chamber method (ibid. - p. 262), which includes a helium mass-spectrometric leak detector with a pumping (vacuuming) device, hermetically connected to a vacuum chamber in which the product being tested is placed, and a helium cylinder to which the product being tested is hermetically connected.

[0011] The main disadvantages of the device are its limited application (it can only be used for products that can be completely sealed to allow placement in a vacuum chamber) and the inconvenience of operation due to the large dimensions of the device and the need to include a helium cylinder in its composition.

[0012] The objective of the proposed invention is to create a compact, highly sensitive device that makes it possible to test the tightness of the units of vacuum cryostat housings of matrix photodetector devices, in particular, sleeve holders, under conditions close to the operating conditions of the VKK units, which operate with one surface under vacuum conditions, while the other is under the influence of high-pressure helium.

[0013] The technical result of the proposed invention consists in increasing the sensitivity and reliability of leak testing by bringing the testing conditions closer to the conditions and specifics of the operation of the VKK units when using a compact control device.

[0014] The essence of the invention lies in the fact that the device, including a helium mass spectrometric leak detector with an evacuation device, unlike the known one, also includes a sleeve, a clamping collar tightened with screws, a housing with a filling valve, a second clamping collar tightened with screws, and high-pressure helium, wherein the sleeve is installed on the working socket of the leak detector and is hermetically connected on one side to the working socket of the leak detector through a flange with an external conical surface and a sealing ring using a clamping collar, and on the other side to the housing through a similar flange with an external conical surface using a second clamping collar, wherein between the flange and the housing the controlled product is placed so that one end of the controlled product contacts the housing through a sealing ring, and the second end of the controlled product contacts the sleeve through a sealing ring, wherein the housing includes a filling valve,consisting of a locking screw and a sealing gasket, and the common internal cavity of the housing and the controlled product is filled with helium under increased pressure. The invention is illustrated in Fig. 1.

[0015] Fig. 1 - diagram of the device for leak testing. Fig. 1 shows: Tested item 1, body 2, sleeve 3, sealing ring 4, sealing ring 5, clamping clamp 6, screw 7, filling hole 8, filling valve screw 9, sealing gasket 10, socket 11, helium mass spectrometric leak detector 12, sealing gasket 13, second clamping clamp 14, screw 15, fastening screw 16.

[0016] The tested article 1, in particular the holder sleeve of the vacuum cryostat housing of the matrix photodetector, is placed between the housing 2 and the sleeve 3 through the sealing rings 4 and 5, which ensure the sealing of the connection together with the clamping collar 6 and the screws 7. Thus, a clamping force is created in the axial direction, due to which the tightness of the connection "housing 2 - tested article 1", as well as the tightness of the connection "sleeve 3 - tested article 1" is ensured. Filling hole 8 serves to fill the internal cavity formed by the housing 2 and the tested article 1 with high-pressure helium, hole 8 is hermetically sealed by a filling valve, in particular consisting of screw 9 and sealing gasket 10.The sleeve 3 is connected to the bell 11 of the helium mass-spectrometric leak detector 12 through the sealing gasket 13, ensuring the tightness of the connection together with the second clamping clamp 14 and screws 15. To ensure the ease of assembly of the device and the reliability of the sealing of the connections, the controlled product can be attached to the body 2 with screws 16.

[0017] The operation of the specific embodiment of the proposed one can be carried out as follows (see Fig. 1). The tested article 1, in a particular case, the holder sleeve of the vacuum cryostat housing of the matrix photodetector device, is placed between the housing 2 and the sleeve 3 through the sealing rings 4 and 5, ensuring the sealing of the connection by tightening the clamping collar 6 with screws 7. In this way, a clamping force is created in the axial direction, due to which the tightness of the connection "housing 2 - tested article 1", as well as the tightness of the connection "sleeve 3 - tested article 1" is ensured. Then, through the filling hole 8, the internal cavity formed by the housing 2 and the tested article 1, is filled with high-pressure helium (up to 50 bar or more), after which the hole 8 is hermetically closed with a filling valve, in a particular case consisting of a screw 9 and a sealing gasket 10.After this, the sleeve 3 is connected to the socket 11 of the helium mass-spectrometric leak detector 12 through the sealing gasket 13, ensuring the tightness of the connection by tightening the second clamping clamp 14 with screws 15. Next, the internal cavity formed by the sleeve 2 and the controlled product 1 is evacuated by the leak detector's pumping device, and, upon completion of the evacuation, the degree of tightness of the controlled product is determined based on the readings of the leak detector.

[0018] In a particular case, the filling valve may consist of a screw 9 and a sealing gasket 10.

[0019] To ensure ease of assembly of the device and reliable sealing of the connections, the controlled product can be additionally secured to the body with 2 16 mm screws.

[0020] The proposed device has been applied in practice to test the tightness of the holder sleeves of vacuum cryostat housings of matrix photodetectors. High measurement sensitivity is achieved. During the tightness test, it was confirmed that the helium leakage rate from the working cavity of the holder sleeve is at a level of 1 ⋅ 10-12 … 1 ⋅ 10-15 Pa⋅m. 3 / sec. The presence of high-pressure helium within the device's internal cavity eliminates the need for an external helium supply, ensuring a compact and safe leak test workstation. Furthermore, leak test reliability is ensured by aligning the test conditions with the operating conditions and specific features of vacuum cryostatted enclosures, with one surface operating in a vacuum and the other exposed to high-pressure helium.

Claims

1. A device for testing the tightness of units of vacuum cryostat housings of photodetector devices, including a helium mass spectrometric leak detector with a vacuuming device, characterized in that it also includes a sleeve, a clamping collar tightened using screws, a housing with a filling valve, a second clamping collar tightened using screws, and high-pressure helium, wherein the sleeve is installed on the working bell of the leak detector and is hermetically connected on one side to the working bell of the leak detector through a flange with an external conical surface and a sealing ring using a clamping collar, and on the other side to the housing through a similar flange with an external conical surface and a sealing ring using a second clamping collar, wherein the product to be tested is placed between the flange and the housing so that one end of the product to be tested contacts the housing through a sealing ring,and the second end of the controlled product contacts the sleeve through a sealing ring, while the housing includes a filling valve, and the common internal cavity of the housing and the controlled product is filled with helium under increased pressure.

2. The device according to paragraph 1, characterized in that the filling valve consists of a screw and a sealing gasket.

3. The device according to paragraphs 1, 2, characterized in that the controlled product is additionally attached to the body using screws.

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