A vacuum test device suitable for liquid helium dewar

Abstract

The vacuum test device applicable to a liquid helium dewar provided by the present invention comprises a buckle, a liquid helium dewar, a pendant, a vacuum test tank, a chuck, an exhaust pipe and a KF joint, wherein the buckle can fix the chuck at the opening of the liquid helium dewar, the pendant and the vacuum test tank are arranged in the liquid helium dewar, the two ends of the vacuum test tank are respectively connected to the exhaust pipe and the pendant, the other end of the exhaust pipe extends out of the liquid helium dewar through the opening, and the other end of the exhaust pipe is connected to the KF joint. The vacuum test device applicable to a liquid helium dewar provided by the present invention places an experimental structure into the vacuum test tank, and then places the vacuum test tank into the liquid helium dewar, thereby greatly reducing the consumption of liquid helium compared with a liquid helium thermostat.

Description

Technical Field

[0001] The invention relates to the technical field of low-temperature vacuum experiments, and in particular to a vacuum testing device suitable for a liquid helium dewar. Background Art

[0002] In order to measure the electrical properties of materials or structures such as resistance in the liquid helium temperature range, it is necessary to conduct experiments in a vacuum chamber in liquid helium. A liquid helium thermostat can provide the temperature conditions for the experiment. However, for small experimental structures, the amount of liquid helium required is very small. If a liquid helium thermostat is used, it is first necessary to output the liquid helium in the liquid helium dewar to cool the liquid helium thermostat and store a certain level of liquid helium. At the end of the experiment, the remaining liquid helium at the bottom of the liquid helium thermostat cannot be returned to the liquid helium dewar for recovery. In this process, a large amount of liquid helium is converted into helium gas for recovery or evacuation, and the experimental cost is high. Summary of the invention

[0003] In view of this, it is necessary to provide a vacuum test device suitable for liquid helium Dewar that can reduce liquid helium consumption and avoid helium leakage in view of the defects of the prior art.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] A vacuum test device suitable for a liquid helium dewar comprises a buckle, a liquid helium dewar, a pendant, a vacuum test tank, a chuck, an exhaust pipe and a KF joint, wherein the buckle can fix the chuck at the opening of the liquid helium dewar, the pendant and the vacuum test tank are arranged in the liquid helium dewar, the two ends of the vacuum test tank are respectively connected to the exhaust pipe and the pendant, the other end of the exhaust pipe extends out of the liquid helium dewar through the opening, and the other end of the exhaust pipe is connected to the KF joint.

[0006] In some preferred embodiments, the vacuum test tank includes a tank body, a tank bottom arranged at the bottom of the tank body, a tank mouth opened on the tank body, a tank cover arranged on the tank mouth, and a channel tube penetrating the tank cover and extending into the tank mouth, wherein the tank body is an elongated round tube, and the tank bottom is in the shape of a stepped truncated cone, wherein the diameter of the small cylinder of the tank bottom is smaller than the inner diameter of the tank body, and the small cylinder is partially inserted into the tank body; the diameter of the large cylinder of the tank bottom is larger than the inner diameter of the tank body, the tank mouth is a cylindrical annular structure with a through hole in the center, a step is provided at one end of the tank mouth close to the tank body, the tank mouth is connected to the tank body through the step, and flange threaded blind holes are distributed along the circumference on the other side of the tank mouth, an annular groove is provided between the through hole and the flange threaded blind hole, and the annular groove can be used to place a low-temperature sealing material, and the low-temperature sealing material is lead or indium or aluminum-magnesium alloy.

[0007] In some preferred embodiments, three through holes are opened at the center of the tank cover, the exhaust pipe passes through the larger through hole, the outer diameter of the channel tube is smaller than the apertures of the remaining two through holes of the tank cover, and the channel tube is connected to the remaining two through holes.

[0008] In some preferred embodiments, the exhaust pipe and the channel pipe are bonded to the through hole at contact corners by welding or low-temperature adhesive.

[0009] In some preferred embodiments, the exhaust pipe is divided into two parts, the lower part of the pipe is made of non-magnetic material, the upper part of the pipe is a stainless steel pipe of the same diameter, and the non-magnetic material is brass.

[0010] In some preferred embodiments, a side sealing male joint is provided along the exhaust pipe and located outside the liquid helium dewar, a side sealing female joint is sleeved on the side sealing male joint, and a side sealing rubber ring is provided between the side sealing male joint and the side sealing female joint.

[0011] In some preferred embodiments, the male joint of the side seal comprises a threaded section, a hexagonal section and a light tube section connected in sequence, the inner diameters of the threaded section, the hexagonal section and the light tube section are all larger than the outer diameter of the exhaust pipe, the outer circumference of the threaded section is threaded, the end face of the light tube section is fixedly connected to the chuck, and the light tube section is a corrugated tube;

[0012] The side sealing female joint is provided with a threaded section matching with the threaded section of the side sealing male joint and a light hole section matching with the exhaust pipe, the threaded section and the light hole section have the same outer diameter, and the aperture of the light hole section is larger than the outer diameter of the exhaust pipe;

[0013] The side sealing rubber ring is annular, the top of the side sealing rubber ring contacts the light hole section of the side sealing female joint, the bottom of the side sealing rubber ring contacts the threaded section of the side sealing male joint, and the inner edge of the side sealing rubber ring fits tightly against the exhaust pipe.

[0014] In some preferred embodiments, the pendant is a metal ball, and the metal ball is connected to the vacuum test tank via a metal chain.

[0015] In some preferred embodiments, a rubber ring is also provided on the chuck.

[0016] The advantages of the present invention using the above technical solution are:

[0017] The vacuum test device suitable for liquid helium dewar provided by the present invention places the experimental structure into the vacuum test tank, and then places the vacuum test tank into the liquid helium dewar, which greatly reduces the consumption of liquid helium compared with the liquid helium thermostat.

[0018] In addition, the vacuum test device suitable for liquid helium dewar provided by the present invention utilizes sealing structures such as side seals to avoid leakage of helium, so that most of the helium enters the helium recovery device. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 The invention provides a vacuum test device suitable for a liquid helium Dewar.

[0021] Figure 2 This is a schematic structural diagram of the vacuum test tank provided by the present invention.

[0022] Figure 3 A structural schematic diagram of a tank mouth is provided for the present invention.

[0023] Figure 4 A structural schematic diagram of a can cover is provided for the present invention.

[0024] Figure 5 A cross-sectional view of a vacuum test device suitable for a liquid helium Dewar provided by the present invention.

[0025] Figure 6 This is a schematic structural diagram of the side seal male joint provided by the present invention.

[0026] Figure 7 This is a schematic structural diagram of the side sealing female joint provided by the present invention. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] See also Figure 1The vacuum test device for a liquid helium dewar provided by the present invention comprises: a buckle 110, a liquid helium dewar 120, a pendant 130, a vacuum test tank 140, a chuck 150, an exhaust pipe 160 and a KF joint 170. The buckle 110 can fix the chuck 150 at an opening 121 of the liquid helium dewar 120. The pendant 130 and the vacuum test tank 140 are arranged in the liquid helium dewar 120. The two ends of the vacuum test tank 140 are respectively connected to the exhaust pipe 160 and the pendant 130. The other end of the exhaust pipe 160 extends out of the liquid helium dewar 120 through the opening 121. The other end of the exhaust pipe 160 is connected to the KF joint 170.

[0029] The vacuum test device suitable for liquid helium dewar provided by the present invention places the experimental structure into the vacuum test tank, and then places the vacuum test tank into the liquid helium dewar, which greatly reduces the consumption of liquid helium compared with the liquid helium thermostat.

[0030] See also Figure 2 , is a schematic structural diagram of the vacuum test tank 140 provided by the present invention, comprising a tank body 141, a tank bottom 142 disposed at the bottom of the tank body 141, a tank opening 143 opened on the tank body 141, a tank cover 144 covering the tank opening 143, and a channel tube 145 penetrating the tank cover 144 and extending into the tank opening 143. It can be understood that the tank bottom 142 and the tank body 141 can be made separately and then welded or bonded together with low-temperature glue, or they can be integrally formed.

[0031] It should be noted that when the vacuum test tank is required not to be magnetic, the vacuum test tank 140 can be made of brass.

[0032] Specifically, the tank body 141 is a long round tube, and the tank bottom 142 is in the shape of a stepped truncated cone, wherein the diameter of the small cylinder of the tank bottom 142 is smaller than the inner diameter of the tank body 141, and the small cylinder is partially inserted into the tank body 141; the diameter of the large cylinder of the tank bottom 142 is larger than the inner diameter of the tank body 141. It can be understood that the diameter of the vacuum test tank 140 is not larger than the aperture of the opening 121 of the liquid helium dewar 120.

[0033] See also Figure 3, a structural schematic diagram of a tank mouth is provided for the present invention, wherein the tank mouth 143 is a cylindrical ring structure with a through hole 1431 in the center, a step 1432 is provided at one end of the tank mouth 143 close to the tank body 141, the tank mouth 143 is connected to the tank body 141 through the step 1432, and flange threaded blind holes 1433 are distributed along the circumference on the other side of the tank mouth 143, an annular groove 1434 is provided between the through hole 1431 and the flange threaded blind hole 1433, and a low-temperature sealing material can be placed in the annular groove 1434, and the low-temperature sealing material is lead or indium or aluminum-magnesium alloy.

[0034] See also Figure 4 , a schematic diagram of the structure of the tank cover is provided for the present invention, wherein the tank cover 144 has the same outer diameter as the tank mouth 143, and a matching flange hole arrangement and size. Three through holes are opened at the center of the tank cover 144, and the exhaust pipe 160 is inserted into the larger through hole 1441, and is welded or bonded with low-temperature glue at the contact corners.

[0035] The channel tube 145 is a thin-walled tube, and the outer diameter of the channel tube 145 is smaller than the aperture of the remaining two through holes 1442 of the tank cover 144. The channel tube 145 is connected to the remaining two through holes 1442, and is welded or bonded with low-temperature glue at the contact corners. There are two holes on the chuck 150, corresponding to the two through holes 1442 connected to the channel tube 145. It can be understood that the channel tube 145 structure is actually a signal line transmission structure, which can be replaced by a low-temperature connector.

[0036] Furthermore, the exhaust pipe 160 is divided into two parts, the lower part of the pipe is made of non-magnetic material, and the upper part of the pipe is a stainless steel pipe with the same diameter, and the non-magnetic material is brass.

[0037] It can be understood that since the exhaust pipe 160 is divided into two parts, the lower part is made of non-magnetic materials such as brass, and the upper part is made of a stainless steel pipe with the same diameter. The stainless steel pipe has a small outer diameter change, is smooth, and has no pits, which can reduce heat conduction. The two parts are welded together and polished after welding. The diameter is the same as the unwelded part, and there is no leakage in the welded joint.

[0038] See also Figure 5 , which is a cross-sectional view of a vacuum testing device suitable for a liquid helium dewar provided by the present invention, a side sealing male joint 170 is provided along the exhaust pipe 160 and located outside the liquid helium dewar 120, a side sealing female joint 180 sleeved on the side sealing male joint 170, and a side sealing rubber ring 190 provided between the side sealing male joint 170 and the side sealing female joint 180, and a rubber ring 200 is also provided on the chuck 150.

[0039] See also Figure 6The side seal male connector 170 includes a threaded section 171, a hexagonal section 172 and a light tube section 173 which are connected in sequence. The inner diameters of the threaded section 171, the hexagonal section 172 and the light tube section 173 are all larger than the outer diameter of the exhaust pipe 160. The outer periphery of the threaded section 171 is threaded and its inner diameter is larger than the outer diameter of the exhaust pipe 160. The hexagonal section 172 is in the shape of a column stretched from a hexagon. The light tube section 173 is fixedly connected to the chuck 150 and is a corrugated tube.

[0040] It can be understood that the inner diameters of the threaded section 171, the hexagonal section 172 and the smooth tube section 173 are all larger than the outer diameter of the exhaust pipe 160, that is, the exhaust pipe 160 can slide freely in the inner hole of the side sealing male joint 170; the smooth tube section 173 and the chuck 150 are firmly and tightly fixed (welded or bonded) together, and helium cannot pass through the gap between the two.

[0041] See also Figure 7 The side sealing female joint 180 includes a threaded section 181 that cooperates with the threaded section 171 of the side sealing male joint 170 and a light hole section 182 that cooperates with the exhaust pipe 160. The outer diameters of the threaded section 181 and the light hole section 182 are the same, and the aperture of the light hole section 182 is larger than the outer diameter of the exhaust pipe 160.

[0042] The side sealing rubber ring 190 is annular in shape, and the upper part of the side sealing rubber ring 190 contacts the light hole section 182 of the side sealing female joint 180, and the lower part of the side sealing rubber ring 190 contacts the threaded section 171 of the side sealing male joint 170. The inner edge of the side sealing rubber ring 190 fits tightly against the exhaust pipe 160 to ensure that helium cannot pass through the gap between the two.

[0043] It can be understood that when the side sealing female joint 180 and the side sealing male joint 170 are not tightened, the exhaust pipe 160 can slide freely in the side sealing rubber ring 190; when the side sealing female joint 180 and the side sealing male joint 170 are tightened, the exhaust pipe 160 is held tightly by the side sealing rubber ring 190, and the friction force generated is several times the sum of the gravity of the pendant, the vacuum test tank, the exhaust pipe and other parts.

[0044] Please refer to Figure 1 The KF connector 170 is connected to an external valve (not shown), the valve is connected to a vacuum pump (not shown), the pendant 130 is a metal ball, and the metal ball is connected to the vacuum test tank 140 through a metal chain.

[0045] The installation method of the vacuum test device suitable for liquid helium dewar provided by the present invention is as follows:

[0046] 1. Glue or weld the tank bottom 142, tank body 141 and tank mouth 143 together; glue or weld the chuck 150 and the side sealing male joint 170 together; glue or weld the channel pipe 145, the exhaust pipe 160 and the tank cover 144 together; and use helium to check the vacuum tightness of the adhesion or welding at each place.

[0047] 2. Pass the wire through the through holes on the channel tube 145 and the chuck 150, install the experimental circuit into the cavity composed of the tank bottom 142, the tank body 141 and the tank mouth 143, and connect the circuit connector.

[0048] 3. Use low-temperature glue to fill the gap between the wire and the channel tube 145 and the gap between the wire and the through hole on the chuck 150, put sealing materials (such as lead, indium, etc.) into the sealing groove of the tank mouth 143, and then connect the tank cover 144 and the flange of the tank mouth 143 together. And use helium to check the vacuum sealing of each adhesion or welding.

[0049] 4. Install the chuck 150, the side sealing male joint 170, the side sealing rubber ring 190, and the side sealing female joint 180 on the exhaust pipe 160 in sequence, and bond or weld the KF joint 170 to the exhaust pipe 160. Connect the KF joint 170 to the valve (not shown), and then to the vacuum pump (not shown). Use the vacuum pump to evacuate air. After reaching the required vacuum degree, close the valve and the vacuum pump. Use helium to check the vacuum tightness of the adhesion or welding at each place.

[0050] 5. Wipe the pendant 130 with alcohol, then dry it, tighten the side sealing female connector 180, remove the liquid helium Dewar 120 access piece of the Dewar, and quickly throw the pendant 130 into the Dewar tank to cause the liquid helium to volatilize.

[0051] It can be understood that the rubber ring 200 , the chuck 150 , and the buckle 110 are installed before the volatilized liquid helium caused by the pendant 130 completely leaves the liquid helium tank.

[0052] 6. Loosen the side sealing female joint 180 so that the exhaust pipe 160 can slide relative to the chuck 150 and the side sealing rubber ring 190, adjust the position of the vacuum test tank 140, and tighten the side sealing female joint 180 so that the exhaust pipe 160 is locked relative to the chuck 150 and the side sealing rubber ring 190.

[0053] It can be understood that during this installation process, sealing structures such as side seals are used to prevent helium leakage, so that most of it enters the helium recovery device.

[0054] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0055] Of course, the positive electrode material of the vacuum test device for liquid helium dewar of the present invention can also have various changes and modifications, and is not limited to the specific structure of the above-mentioned embodiment. In short, the protection scope of the present invention should include those changes or substitutions and modifications that are obvious to ordinary technicians in the field.

Claims

1. A vacuum test device suitable for a liquid helium dewar, characterized in that: The utility model comprises a buckle, a liquid helium dewar, a pendant, a vacuum test tank, a chuck, an exhaust pipe and a KF joint. The buckle can fix the chuck at the opening of the liquid helium dewar. The pendant and the vacuum test tank are arranged in the liquid helium dewar. The two ends of the vacuum test tank are respectively connected with the exhaust pipe and the pendant. The other end of the exhaust pipe extends out of the liquid helium dewar through the opening. The other end of the exhaust pipe is connected with the KF joint. A side sealing male joint, a side sealing female joint sleeved on the side sealing male joint and a side sealing rubber ring arranged between the side sealing male joint and the side sealing female joint are arranged along the exhaust pipe and the part outside the liquid helium dewar. The pendant causes the liquid helium to volatilize in the liquid helium dewar. Before the liquid helium caused by the pendant completely leaves the liquid helium dewar, the rubber ring, the chuck and the buckle are installed.

2. The vacuum test device suitable for liquid helium dewar according to claim 1, characterized in that: The vacuum test tank comprises a tank body, a tank bottom arranged at the bottom of the tank body, a tank mouth opened on the tank body, a tank cover arranged on the tank mouth, and a channel tube penetrating the tank cover and extending into the tank mouth. The tank body is an elongated round tube, and the tank bottom is in the shape of a stepped truncated cone, wherein the diameter of the small cylinder of the tank bottom is smaller than the inner diameter of the tank body, and the small cylinder is partially inserted into the tank body; the diameter of the large cylinder of the tank bottom is larger than the inner diameter of the tank body, and the tank mouth is a cylindrical annular structure with a through hole in the center, and a step is provided at one end of the tank mouth close to the tank body, and the tank mouth is connected to the tank body through the step, and flange threaded blind holes are distributed along the circumference on the other side of the step of the tank mouth, and an annular groove is provided between the through hole and the flange threaded blind hole, and the annular groove can be used to place a low-temperature sealing material, and the low-temperature sealing material is lead or indium or aluminum-magnesium alloy.

3. The vacuum test device suitable for liquid helium dewar according to claim 2, characterized in that: Three through holes are opened at the center of the tank cover, and the exhaust pipe passes through the larger through hole. The outer diameter of the channel pipe is smaller than the apertures of the remaining two through holes of the tank cover, and the channel pipe is connected to the remaining two through holes.

4. The vacuum test device suitable for liquid helium dewar according to claim 3, characterized in that: The exhaust pipe and the channel pipe are bonded to the through hole at contact corners by welding or low-temperature adhesive.

5. The vacuum test device suitable for liquid helium dewar according to claim 1, characterized in that: The exhaust pipe is divided into two parts, the lower part is made of non-magnetic material, and the upper part is a stainless steel pipe with the same diameter, and the non-magnetic material is brass.

6. The vacuum test device suitable for liquid helium dewar according to claim 5, characterized in that: The side sealing male joint comprises a threaded section, a hexagonal section and a smooth tube section which are connected in sequence, the inner diameters of the threaded section, the hexagonal section and the smooth tube section are all larger than the outer diameter of the exhaust pipe, the outer circumference of the threaded section is threaded, the end of the smooth tube section is fixedly connected to the chuck, and the smooth tube section is a corrugated tube; The side sealing female joint is provided with a threaded section matching with the threaded section of the side sealing male joint and a light hole section matching with the exhaust pipe, the threaded section and the light hole section have the same outer diameter, and the aperture of the light hole section is larger than the outer diameter of the exhaust pipe; The side sealing rubber ring is annular, the top of the side sealing rubber ring contacts the light hole section of the side sealing female joint, the bottom of the side sealing rubber ring contacts the threaded section of the side sealing male joint, and the inner edge of the side sealing rubber ring fits tightly against the exhaust pipe.

7. The vacuum test device suitable for liquid helium dewar according to claim 1, characterized in that: The pendant is a metal ball, and the metal ball is connected to the vacuum test tank through a metal chain.

8. The vacuum test device suitable for liquid helium dewar according to claim 1, characterized in that: The chuck is also provided with a rubber ring.

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