Vacuum standard leak

Abstract

The present application relates to the technical field of vacuum standard leak, in particular to a vacuum standard leak, which comprises an upper connecting piece, a lower connecting piece, a baffle, an upper indium ring, a lower indium ring and an indium block, helium or other leak detection gas flowing from an air inlet port successively passes through the inner wall of the upper indium ring, the inside of the upper indium ring, the bottom surface of the upper indium ring, the top end surface of the indium block, the bottom end surface of the indium block, the top surface of the lower indium ring, the inside of the lower indium ring and the inner wall of the lower indium ring and then flows out from an air outlet port. Overall, the upper indium ring, the indium block and the lower indium ring are used to build a micro-permeation channel for the leak detection gas, compared with the way that the leak detection gas directly penetrates along the vertical direction of the surface where the permeation membrane is located, the path for micro-permeation is greatly lengthened, and at the same time, part of the leak detection gas flowing into the permeation channel can be diffused into the atmosphere for loss.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of vacuum standard leak, in particular to a vacuum standard leak. BACKGROUND

[0002] Vacuum leak detection technology is one of the important branches of vacuum technology. For vacuum containers or other sealed containers, vacuum leak detection technology is mainly used to determine whether there is a leakage fault, to determine the specific location of the leakage and to measure the size of the leakage. Common leak detection methods of vacuum leak detection technology include pressure change leak detection method, bubble leak detection method and mass spectrometric leak detection method, etc. Among them, mass spectrometric leak detection method has become one of the most widely used leak detection methods due to its high sensitivity and other advantages.

[0003] Mass spectrometric leak detection method uses mass spectrometer to convert the flow rate of tracer gas leaked through the vacuum standard leak into the ion current of the mass spectrometer, and realizes the detection of the leak rate by measuring the size of the ion current signal. The vacuum standard leak is an essential measuring instrument in mass spectrometric leak detection method. The vacuum standard leak is used to calibrate the mass spectrometric leak detection system, realizing the conversion between the ion current signal and the tracer gas leak rate.

[0004] Vacuum standard leaks can be divided into two categories: permeation type vacuum standard leaks and channel type vacuum standard leaks. The leak element of the permeation type vacuum standard leak is made by using the principle that some materials have permeability to gas, such as quartz helium permeation standard leak. The leak element of the channel type vacuum standard leak is a physical throttling gas channel, such as capillary standard leak and metal crush standard leak.

[0005] Since the lower limit of the leak rate of the permeation type vacuum standard leak is significantly lower than that of the channel type vacuum standard leak, the mass spectrometric leak detection method usually adopts the permeation type vacuum standard leak. The quartz helium permeation standard leak is the most widely used permeation type vacuum standard leak. When the quartz helium permeation standard leak is used as a specific vacuum standard leak, the tracer gas passes through the quartz film along the vertical direction of the surface where the quartz helium permeation standard leak is located. According to the leak rate calculation formula of the quartz helium permeation standard leak, when the material permeation coefficient K and the upstream and downstream pressure difference p remain unchanged, the leak rate Q is proportional to the area A of the quartz film and inversely proportional to the thickness D of the quartz film. In order to reduce the lower limit of the permeation type vacuum standard leak, it is necessary to reduce the area A of the quartz film or increase the thickness D of the quartz film. At present, the lower limit of the leak rate of the quartz helium permeation standard leak has reached the limit, and with the continuous improvement of leak detection technology, it is necessary to further reduce the lower limit of the leak rate of the vacuum standard leak. If the leak rate is reduced by several orders of magnitude on the basis of the existing leak rate, the area A of the quartz film needs to be reduced by several orders of magnitude, or the thickness D of the quartz film needs to be increased by several orders of magnitude. However, it is not practical to make the permeation area of the quartz film very small or the thickness of the quartz film very large in actual production.

[0006] Therefore, how to further reduce the lower limit of the leakage rate of the vacuum standard leak to meet higher leak detection requirements has become a technical problem that needs to be solved urgently by those skilled in the art. Summary of the Invention

[0007] The present invention provides a vacuum standard leak hole, which is used to solve the problem of how to further reduce the lower limit of the leakage rate of the vacuum standard leak hole.

[0008] The present invention provides a vacuum standard leak, comprising:

[0009] The upper connecting member is formed with an air inlet and an upper receiving groove is formed on the bottom surface;

[0010] The lower connecting member is formed with an air outlet; the air outlet is arranged opposite to the air inlet; a lower receiving groove is formed on the top surface of the lower connecting member; the lower connecting member is connected to the upper connecting member;

[0011] A baffle is installed between the upper connecting member and the lower connecting member to isolate the air inlet from the air outlet; a flow hole is formed on the baffle;

[0012] An upper indium ring is embedded in the upper receiving groove, and an upper indium ring is formed at the bottom end;

[0013] The lower indium ring is embedded in the lower accommodating groove and has a lower indium ring formed on the top;

[0014] an indium block embedded in the flow hole;

[0015] The helium gas flowing in from the air inlet passes through the inner wall of the upper indium ring, the interior of the upper indium ring, the bottom surface of the upper indium ring, the indium block, the top surface of the lower indium ring, the interior of the lower indium ring and the inner wall of the lower indium ring in sequence, and then flows out from the air outlet.

[0016] In some embodiments, a protrusion is formed at the bottom end of the upper connecting member; an upper receiving groove is formed at the bottom end of the protrusion;

[0017] The top end of the lower connecting piece is formed with a groove matched with the raised portion; the bottom end of the groove is formed with a lower accommodating groove; and a blocking piece is installed in the groove.

[0018] In some embodiments, the upper connecting member and the lower connecting member are flanges.

[0019] In some embodiments, the upper connecting member and the lower connecting member are detachably connected.

[0020] In some embodiments, there are four flow-through holes evenly distributed along the circumference of the baffle; correspondingly, there are four indium blocks, which are embedded in the flow-through holes in a one-to-one correspondence with the four flow-through holes.

[0021] In some embodiments, the baffle is circular, has a diameter of 20 mm, and a thickness of 0.5 mm;

[0022] The diameter of each flow-through hole is 1 mm, and the distance between the hole center and the center of the baffle is 4.5 mm;

[0023] The cross-section of each indium block has a diameter of 1 mm and an axial length of 0.5 mm;

[0024] The inner diameter of the upper indium ring is 4 mm and the outer diameter is 14 mm;

[0025] The inner diameter of the lower indium ring is 4 mm and the outer diameter is 14 mm.

[0026] In some embodiments, the upper connecting member, the lower connecting member and the blocking piece are made of stainless steel.

[0027] The beneficial effects of the present invention are as follows: The vacuum standard leak of the present invention is provided with an upper connecting member, a lower connecting member, a baffle, an upper indium ring, a lower indium ring, and an indium block. The upper indium ring is embedded in the upper accommodating groove, and the bottom end surface of the upper indium ring is formed with an upper indium ring. The lower indium ring is embedded in the lower accommodating groove, and the top end surface of the lower indium ring is formed with a lower indium ring. The indium block is embedded in the flow-through hole. Helium or other leak-traceable gas flowing in from the air inlet passes through the inner wall of the upper indium ring, the interior of the upper indium ring, the bottom surface of the upper indium ring, the top surface of the indium block, the bottom end surface of the indium block, the top surface of the lower indium ring, the interior of the lower indium ring, and the inner wall of the lower indium ring, and then flows out from the air outlet. Compared with traditional vacuum standard leaks, indium material is used as the permeation medium for the leak-traceable gas, and the tiny gas channels generated in the material after the indium material is significantly deformed serve as trace permeation channels for the leak-traceable gas. In the upper indium ring, the leak-traceable gas diffuses in trace amounts from the inside to the outside along the radial direction of the upper indium ring. Part of the leak-trace gas that penetrates the upper indium ring flows toward the indium block, while the remaining portion diffuses through the outer ring of the upper indium ring into the atmosphere. Furthermore, the ratio of gas flowing through the upper indium ring toward the indium block and toward the atmosphere can be quantitatively controlled. This ratio depends on the number and diameter of the indium blocks—that is, the number and diameter of the flow-through holes in the baffle. A greater number or a larger diameter results in a greater proportion of gas flowing toward the indium block. The outer ring of the upper indium ring also serves to isolate the gas from the atmosphere. In the lower indium ring, the leak-trace gas diffuses minutely along the radial direction of the lower indium ring, from the outside to the inside. Part of the leak-trace gas that penetrates the lower indium ring diffuses through the outer ring of the lower indium ring toward the gas outlet, while the remaining portion diffuses through the outer ring of the lower indium ring into the atmosphere. The ratio of gas flowing through the lower indium ring toward the gas outlet and toward the atmosphere can be quantitatively controlled. The outer ring of the lower indium ring also serves to isolate the gas from the atmosphere. Overall, by constructing a trace permeation channel for the leak-indicating gas with the help of the upper indium ring, the indium block, and the lower indium ring, the path for trace permeation is greatly extended compared to the method in which the leak-indicating gas directly permeates in the vertical direction of the surface where the permeable membrane is located. At the same time, part of the leak-indicating gas flowing into the permeation channel can be diffused into the atmosphere for loss. It should be pointed out that in the entire path of the leak-indicating gas flow, the resistance encountered when flowing along the radial direction of the upper indium ring and along the radial direction of the lower indium ring is relatively large, while the resistance encountered when flowing from top to bottom along the indium block is relatively small. Therefore, when the distance between the top surface of the upper connector and the bottom end of the lower connector remains unchanged, by compressing the thickness of the upper indium ring and the lower indium ring, or reducing the number and diameter of the flow-through holes, or increasing the distance between the center of the flow-through hole and the center of the baffle, the lower limit of the leak rate of the vacuum standard leak can be significantly reduced, and a vacuum standard leak with an extremely small leak rate can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Schematic diagram of the structure of some specific embodiments of a vacuum standard leak of the present invention;

[0029] Figure 2 yes Figure 1The schematic diagram of the vacuum standard leak before assembly is shown;

[0030] Figure 3 yes Figure 1 A partial enlarged view of area A in the middle;

[0031] Figure 4 yes Figure 1 Schematic diagrams of the structures of some specific embodiments of baffles in a vacuum standard leak are shown;

[0032] Figure 5 It is a structural schematic diagram of some specific embodiments of a test device of the present invention.

[0033] In the accompanying drawings, 100 is a vacuum standard leak; 110 is an upper connecting piece; 111 is an air inlet; 112 is an upper accommodating groove; 113 is a raised portion; 114 is a threaded hole; 120 is a lower connecting piece; 121 is an air outlet; 122 is a lower accommodating groove; 123 is a groove; 130 is a baffle; 131 is a flow-through hole; 140 is an upper indium ring; 141 is an upper indium ring; 150 is a lower indium ring; 151 is a lower indium ring; 160 is an indium block; 210 is a gas cylinder; 220 is a mass spectrometer chamber; 231 is an auxiliary fore-stage pump; 232 is a fore-stage pump; 240 is a quadrupole mass spectrometer; 250 is a liquid nitrogen cold trap; 260 is a molecular pump group; 270 is an ion pump; 280 is a getter pump; 291 is a dynamic method standard leak; 292 is an accumulation method standard leak. DETAILED DESCRIPTION

[0034] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0035] As described in the background art, the lower limit of the leak rate of a quartz helium-infiltrated standard leak has currently reached its limit. With the continuous improvement of leak detection technology, it is necessary to further reduce the lower limit of the leak rate of a vacuum standard leak. If the existing leak rate is to be reduced by several orders of magnitude, the area A of the quartz film needs to be reduced by several orders of magnitude, or the thickness D of the quartz film needs to be increased by several orders of magnitude. However, in actual production, it is unrealistic to make the permeable area of ​​the quartz film very small or to make the thickness of the quartz film very large. Therefore, how to further reduce the lower limit of the leak rate of the vacuum standard leak to meet higher leak detection requirements has become a technical problem that needs to be solved urgently by those skilled in the art.

[0036] To solve the above problems, refer to Figure 1 、 Figure 2 、 Figure 3 and Figure 4In one aspect, the present invention provides a vacuum standard leak 100, comprising an upper connector 110, a lower connector 120, a baffle 130, an upper indium ring 140, a lower indium ring 150, and an indium block 160. The lower connector 120 is connected to the upper connector 110. An air inlet 111 is formed on the upper connector 110. An air outlet 121 is formed on the lower connector 120. The air outlet 121 is arranged vertically opposite the air inlet 111. An upper accommodating groove 112 with a closed annular structure is formed on the bottom surface of the upper connector 110. The upper accommodating groove 112 facilitates the positioning and installation of the upper indium ring 140. A lower accommodating groove 122 with a closed annular structure is formed on the top surface of the lower connector 120. The lower accommodating groove 122 facilitates the positioning and installation of the lower indium ring 150. The baffle 130 is installed between the upper connector 110 and the lower connector 120 to separate the air inlet 111 from the air outlet 121. A flow hole 131 is formed on the baffle 130. The flow hole 131 is offset from the air inlet 111 / air outlet 121 and is directly opposite the upper accommodating groove 112 and the lower accommodating groove 122. The upper indium ring 140 is embedded in the upper accommodating groove 112. The lower indium ring 150 is embedded in the lower accommodating groove 122. When the upper connecting member 110 and the lower connecting member 120 are connected and closed, the bottom end surface of the upper indium ring 140 is compressed and deformed to form the upper indium ring 141, and the top end surface of the lower indium ring 150 is compressed and deformed to form the lower indium ring 151. The indium block 160 is embedded in the flow hole 131. Figure 1 and Figure 3The middle arrow indicates the flow direction of the leak indicator gas. Helium or other leak indicator gas flowing in from the gas inlet 111 passes through the inner wall of the upper indium ring 141, the interior of the upper indium ring 141, the bottom surface of the upper indium ring 141, the top surface of the indium block 160, the bottom surface of the indium block 160, the top surface of the lower indium ring 151, the interior of the lower indium ring 151, and the inner wall of the lower indium ring 151, before exiting the gas outlet 121. Compared to the traditional vacuum standard leak 100, this uses indium material as the permeation medium for the leak indicator gas. The tiny gas channels created by the large deformation of the indium material serve as trace permeation channels for the leak indicator gas. Within the upper indium ring 141, the leak indicator gas diffuses radially from the inside to the outside of the upper indium ring 141. Part of the leak indicator gas that penetrates the upper indium ring 141 flows toward the indium block 160, while the rest diffuses through the outer ring of the upper indium ring 141 into the atmosphere. The outer ring of the upper indium ring 141 also serves to isolate the atmosphere. In the lower indium ring 151, the leakage indicator gas diffuses in trace amounts from the outside to the inside along the radial direction of the lower indium ring 151. Part of the leakage indicator gas that penetrates into the lower indium ring 151 passes through the outer ring of the lower indium ring 151 and diffuses to the gas outlet 121, while the other part passes through the outer ring of the lower indium ring 151 and diffuses into the atmosphere. The outer ring of the lower indium ring 151 also serves to isolate the atmosphere. Overall, the trace penetration channel for the leakage indicator gas is constructed with the help of the upper indium ring 141, the indium block 160 and the lower indium ring 151. Compared with the method in which the leakage indicator gas directly penetrates in the vertical direction of the surface where the permeable membrane is located, the path for trace penetration is greatly extended. At the same time, part of the leakage indicator gas that flows into the penetration channel can be diffused into the atmosphere for loss. It should be noted that, throughout the entire flow path of the leak-indicating gas, the resistance encountered is relatively large when flowing radially along the upper indium ring 141 and the lower indium ring 151, while the resistance encountered is relatively small when flowing from top to bottom along the indium block 160. Therefore, while maintaining the distance between the top surface of the upper connector 110 and the bottom end of the lower connector 120, by compressing the thickness of the upper indium ring 141 and the lower indium ring 151, or by reducing the number and diameter of the flow-through holes, or by increasing the distance between the center of the flow-through holes and the center of the baffle, the lower limit of the leak rate of the vacuum standard leak 100 can be significantly reduced, resulting in a vacuum standard leak 100 with an extremely low leak rate.

[0037] It should be noted that if the leak-indicating gas is allowed to penetrate in trace amounts along the radial direction of the quartz film, it is difficult to implement. Even if the leak-indicating gas is allowed to penetrate in trace amounts along the radial direction of the quartz film, the test results show that the radial leakage rate of the quartz film is still an order of magnitude higher than that of the indium film. Therefore, an indium film is used. In theory, the indium film can also penetrate longitudinally, but according to the test results, the internal gas permeation principle of the indium material is due to large-scale deformation, which causes a large number of microscopic crystal defects to be generated inside the indium material. The reason why radial penetration is successful is that the bottom end of the upper indium ring 140 is squeezed and extended into the upper indium ring 141, and the top end of the lower indium ring 150 is squeezed and extended into the lower indium ring 151, and the indium sheet itself is difficult to undergo large deformation in the thickness direction. It is not feasible to directly use the leak-indicating gas to penetrate in the vertical direction of the surface of the indium sheet.

[0038] The assembly process of the vacuum standard leak 100 is as follows:

[0039] First, a length of indium wire is bent into an upper indium ring 140 and installed in the upper receiving groove 112. A length of indium wire is then bent into a lower indium ring 150 and installed in the lower receiving groove 122. An indium block 160 is then inserted into the flow hole 131 of the baffle 130. The baffle 130 is then placed between the upper connector 110 and the lower connector 120. The upper connector 110 and the lower connector 120 are then connected. Because the cross-sectional diameter of the upper indium ring 140 is larger than the cross-sectional area of ​​the upper receiving groove 112, during the connection process, the bottom end of the upper indium ring 140 abuts against the top surface of the baffle 130. When squeezed, the ring's ductility and fluidity cause it to "overflow" out of the upper receiving groove 112, forming an upper indium ring 141 that fills the space between the upper connector 110 and the baffle 130. Because the cross-sectional diameter of lower indium ring 150 is larger than the cross-sectional area of ​​lower accommodating groove 122, during the connection process between upper connector 110 and lower connector 120, the top end of lower indium ring 150 abuts against the bottom end of baffle 130. When squeezed, due to its ductility and fluidity, it "overflows" out of lower accommodating groove 122, forming lower indium ring 151 that fills the space between lower connector 120 and baffle 130. Simultaneously, under the action of the squeezing force, upper indium ring 141, indium block 160, and lower indium ring 151 are squeezed into a single structure, which not only avoids the influence of the upstream high-purity leak-triggering gas environment and atmospheric environment on the downstream leak rate, but also forms a double diversion of helium during the permeation process, further reducing the lower limit of the leak rate.

[0040] Preferably, the air inlet 111 is formed in the middle of the upper connecting member 110 , and the air outlet 121 is formed in the middle of the lower connecting member 120 .

[0041] Specifically, in this example, a protrusion 113 is formed at the bottom end of the upper connector 110, and a corresponding groove 123 is formed at the top end of the lower connector 120 to match the protrusion 113. The cooperation between the protrusion 113 and the groove 123 improves the stability of the connection and prevents misalignment between the upper and lower connectors 110, 120. An upper receiving groove 112 is formed on the bottom end surface of the protrusion 113, and a lower receiving groove 122 is formed on the bottom end surface of the groove 123. A stopper 130 is mounted in the groove 123 to limit radial movement of the stopper 130.

[0042] Preferably, the upper connector 110 and the lower connector 120 are flanges, which increase the contact area between the upper and lower connectors 110, 120, thereby enhancing the stability of the connection. The upper and lower connectors 110, 120, and the baffle 130 are made of stainless steel, which has high strength and rigidity. Furthermore, stainless steel is not easily permeated or adsorbed by leak-traceable gas.

[0043] In some embodiments, the upper connecting member 110 and the lower connecting member 120 are detachably connected to facilitate assembly, use, and disassembly and replacement of the vacuum standard leak 100. Specifically, the connection can be made by screwing, riveting, or clamping.

[0044] In other embodiments, the upper connecting member 110 and the lower connecting member 120 are connected in a non-detachable manner to improve the stability of the connection between the upper connecting member 110 and the lower connecting member 120. Specifically, welding can be used for connection.

[0045] In the example, if Figure 1 and Figure 2 As shown, the edge of the upper connecting member 110 is evenly provided with three, four, five or six threaded holes 114 along the circumference, and correspondingly, the edge of the lower connecting member 120 is also evenly provided with three, four, five or six threaded holes 114 along the circumference. The upper connecting member 110 and the lower connecting member 120 are connected by bolts and nuts through the threaded holes 114. It should be noted that when the flange surfaces of the upper connecting member 110 and the lower connecting member 120 are fitted, a gap of 1 mm is left in the middle. Since indium has strong ductility and will plastically deform, changes in preload force will loosen the structure, so the bolts and nuts need to be tightened. The thickness of the upper indium ring 140 and the lower indium ring 150 is compressed and adjusted by increasing the thickness of the baffle 130. Under the action of the preload force of the bolts and nuts, the upper indium ring 141, the indium block 160 and the lower indium ring 151 are squeezed into an integrated structure. It not only avoids the influence of the upstream high-purity leak-indicating gas environment and atmospheric environment on the downstream leak rate, but also forms two diversions of helium during the permeation process, further reducing the lower limit of the leak rate.

[0046] Specifically, in the example, Figure 1 andFigure 4 As shown, there are one, two, three, four, or five flow-through holes 131, evenly distributed along the circumference of the baffle 130. Correspondingly, there are three, four, or five indium blocks 160, which are embedded in the flow-through holes 131 in a one-to-one correspondence with the flow-through holes 131. The baffle 130 is circular, with a diameter of 20 mm and a thickness of 0.5 mm. The diameter of each flow-through hole 131 is 1 mm, and the distance between the hole center and the center of the baffle 130 is 4.5 mm. The cross-sectional diameter of each indium block 160 is 1 mm, and the axial length is 0.5 mm. The cross-sectional diameter of the upper indium ring 140 and the lower indium ring 150 is 2 mm. The inner diameter of the upper indium ring is 4 mm, and the outer diameter is 14 mm. The inner diameter of the lower indium ring is 4 mm, and the outer diameter is 14 mm. In addition to controlling the thickness of the upper indium ring 141 and the lower indium ring 151, the leakage rate of the vacuum standard leak hole 100 can be further reduced by increasing the distance from the center of the flow-through hole 131 to the center of the baffle 130, reducing the aperture of the flow-through hole 131, or reducing the number of flow-through holes 131, so that the lower limit of the leakage rate is more controllable.

[0047] Reference Figure 5On the other hand, the present invention also provides a test device, including a gas cylinder 210, a mass spectrometer chamber 220, an auxiliary backing pump 231, a quadrupole mass spectrometer 240, a liquid nitrogen cold trap 250, a molecular pump group 260, an ion pump 270, a getter pump 280, a dynamic method standard leak 291, an accumulation method standard leak 292, a backing pump 232, and a vacuum standard leak 100 provided in any embodiment. The vacuum standard leak 100 is connected to the gas cylinder 210 and the mass spectrometer chamber 220 respectively. The auxiliary backing pump 231 is connected to the upstream pipeline of the test piece. The quadrupole mass spectrometer 240 is connected to the mass spectrometer chamber 220. The liquid nitrogen cold trap 250 is arranged on the periphery of the mass spectrometer chamber 220. The molecular pump group 260 is connected to the mass spectrometer chamber 220. The ion pump 270 is connected to the mass spectrometer chamber 220 and is used to maintain a high vacuum environment in the mass spectrometer chamber 220 when the system is shut down. Getter pump 280 is connected to mass spectrometry chamber 220. Dynamic standard leak 291 is connected to mass spectrometry chamber 220. Accumulative standard leak 292 is connected to mass spectrometry chamber 220. Fore pump 232 is connected to molecular pump assembly 260. It should be noted that the leak rates of dynamic standard leak 291 and accumulative standard leak 292 are calibrated and known, while vacuum standard leak 100 is the leak to be measured. The leak rate of vacuum standard leak 100 of the present invention can be measured using test equipment. Gas cylinder 210 is used to inflate and deflate vacuum standard leak 100. The auxiliary foreline pump 231 is used to evacuate the vacuum standard leak 100. When the vacuum accumulation method is used to detect leaks in the vacuum standard leak 100, the liquid nitrogen cooling hydrant is filled with liquid nitrogen so that the liquid nitrogen envelops the mass spectrometer chamber 220, and the mass spectrometer chamber 220 is pre-cooled. After the liquid nitrogen in the liquid nitrogen cooling hydrant has evaporated and the temperature in the mass spectrometer chamber 220 has dropped, the liquid nitrogen cooling hydrant is filled with liquid nitrogen again. The test equipment can perform positive pressure leak detection, negative pressure leak detection, and back pressure leak detection on the vacuum standard leak 100. When the leak rate is greater than 1×10 -12 Pa·m 3 When testing a vacuum standard leak of 100 / s, the vacuum dynamic leak detection method is used; when the leak rate is less than 1×10 -12 Pa·m 3 When testing a vacuum standard leak of 100 / s, the vacuum accumulation leak detection method is used.

[0048] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0049] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0050] In the present invention, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0051] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples without contradiction.

[0052] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A vacuum standard leak, characterized in that: include: The upper connecting member is formed with an air inlet and an upper receiving groove is formed on the bottom surface; The lower connecting piece is formed with an air outlet; the air outlet is arranged opposite to the air inlet; A lower accommodating groove is formed on the top surface of the lower connecting member; the lower connecting member is connected to the upper connecting member; a baffle installed between the upper connecting member and the lower connecting member to isolate the air inlet from the air outlet; a flow-through hole is formed on the baffle; An upper indium ring is embedded in the upper accommodating groove, and an upper indium ring is formed at the bottom end; A lower indium ring is embedded in the lower accommodating groove and has a lower indium ring formed on the top; an indium block embedded in the flow hole; The helium gas flowing in from the air inlet passes through the inner wall of the upper indium ring, the interior of the upper indium ring, the bottom surface of the upper indium ring, the indium block, the top surface of the lower indium ring, the interior of the lower indium ring and the inner wall of the lower indium ring in sequence, and then flows out from the air outlet.

2. The vacuum standard leak according to claim 1, characterized in that: A protrusion is formed at the bottom end of the upper connecting member; and the upper accommodating groove is formed at the bottom end of the protrusion; A groove adapted to the protruding portion is formed at the top end of the lower connecting member; a lower accommodating groove is formed at the bottom end of the groove; and the blocking piece is installed in the groove.

3. The vacuum standard leak according to claim 1, characterized in that: The upper connecting piece and the lower connecting piece are flanges.

4. The vacuum standard leak according to claim 1, characterized in that: The upper connecting piece and the lower connecting piece are detachably connected.

5. The vacuum standard leak according to claim 1, characterized in that: There are four flow-through holes, which are evenly distributed along the circumference of the baffle; correspondingly, there are four indium blocks, which are embedded in the flow-through holes in a one-to-one correspondence with the four flow-through holes.

6. The vacuum standard leak according to claim 5, characterized in that: The baffle is circular, with a diameter of 20 mm and a thickness of 0.5 mm; The diameter of each of the flow-through holes is 1 mm, and the distance between the hole center and the center of the baffle is 4.5 mm; The cross-section of each indium block has a diameter of 1 mm and an axial length of 0.5 mm; The inner diameter of the upper indium ring is 4 mm and the outer diameter is 14 mm; The inner diameter of the lower indium ring is 4 mm and the outer diameter is 14 mm.

7. The vacuum standard leak according to claim 1, characterized in that: The upper connecting piece, the lower connecting piece and the blocking piece are made of stainless steel.

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