An ultra-low temperature environment test device with internal vacuum

Abstract

The present invention discloses an ultra-low temperature environment test device with internal vacuum, comprising a vacuum chamber, a refrigeration device, a sample rod chamber, a sample rod, a helium circulation device, a heater, a temperature sensor and a temperature controller. The ultra-low temperature environment test device provides an internal vacuum environment with a lower temperature and precise temperature control for sample testing. The present invention also discloses a sliding sealing device, which is provided with a sliding sealing chamber away from the side of the sample rod chamber and an air sealing chamber close to the side of the sample rod chamber, the sliding sealing chamber is provided with a sliding sealing chamber evacuation port, and the air sealing chamber is provided with an air sealing chamber evacuation port. The sliding sealing device can conveniently replace the sample rod and prevent air leakage.

Description

Technical Field

[0001] The invention belongs to the technical field of low-temperature refrigeration, and in particular relates to a test device for providing an ultra-low temperature environment. Background Art

[0002] The low temperature environment test device is a convenient and practical laboratory low temperature system, which can provide a temperature environment of 4K to 373K (-269℃ to +100℃), and can be used for research, testing and experiments in new materials, superconductivity, electronic devices, condensed matter physics, surface physics, etc. For example, Chinese patent application CN107246741A discloses a low temperature thermostat, which includes a vacuum cavity in which a cooled sample is placed and a low temperature refrigerator, the vacuum cavity and the low temperature refrigerator are fixed independently of each other, and the low temperature refrigerator and the vacuum cavity are connected by a rubber bellows, the low temperature refrigerator and the vacuum cavity form a sealed cavity filled with a heat-conducting medium with the rubber bellows, and the cooling head of the low temperature refrigerator is inserted into the sealed cavity. Most of the tested samples are installed inside the low temperature thermostat through a sample rod.

[0003] It should be noted that the ultra-low temperature environment test device in the prior art has certain shortcomings, mainly including:

[0004] 1. The operating temperature range of the test equipment is narrow and the temperature control accuracy is low;

[0005] 2. When replacing the sample rod, the system needs to be shut down to return to normal temperature, which is cumbersome and time-consuming. Even if some equipment does not need to return to normal temperature, there is still air leakage into the system, causing system blockage.

[0006] Due to the above-mentioned deficiencies, existing low-temperature environment testing equipment has application limitations in testing the magnetic transmission properties (such as magnetic strength), electrical transmission properties (such as AC sensitivity), and thermal transmission properties (such as specific heat, thermal conductivity, and contact thermal resistance) of materials. Summary of the invention

[0007] The present invention makes improvements on the existing technical problems, that is, the technical problem to be solved by the present invention is to provide an ultra-low temperature environment testing device with internal vacuum which has lower temperature and can be precisely controlled.

[0008] The technical solution provided by the present invention is:

[0009] An ultra-low temperature environment test device with internal vacuum, characterized in that it comprises: a vacuum cavity, used to form a vacuum area, on which a first helium injection port is provided; a refrigeration device, having a primary cold head and a secondary cold head extending into the vacuum area; a sample rod cavity, installed on the vacuum cavity, comprising an insertion portion inserted into the vacuum area, the insertion portion being provided with a second helium injection port, and the sample rod cavity is also provided with a helium outflow port; a sample rod, used for the installation and placement of a sample, inserted into the sample rod cavity during the test; a helium circulation device, comprising an interconnected helium storage tank and an oil-free dry pump, and also comprising an activated carbon filter element, a primary heat exchanger, a secondary heat exchanger, and a liquid accumulation cavity located in the vacuum area , a low temperature regulating valve, and a sample chamber heat exchanger, the first-level heat exchanger is thermally connected to the first-level cold head, the second-level heat exchanger is thermally connected to the second-level cold head, and the helium flowing out of the helium storage tank driven by the oil-free dry pump flows back to the helium storage tank after passing through the first helium injection port, the activated carbon filter element, the first-level heat exchanger, the second-level heat exchanger, the liquid accumulation chamber, the low temperature regulating valve, the sample chamber heat exchanger, the second helium injection port, and the helium flow outlet in sequence; a heater and a temperature sensor are installed near the second-level cold head, the sample chamber heat exchanger and the sample; and a temperature controller is communicatively connected with the heater and the temperature sensor.

[0010] Furthermore, the above-mentioned inner vacuum ultra-low temperature environment testing device also includes a cold shield located in the vacuum area and thermally connected to the secondary cold head.

[0011] Furthermore, a superconducting magnet is installed around the sample rod cavity.

[0012] Furthermore, the refrigeration device is a GM refrigerator.

[0013] The technical problem to be further solved by the present invention is to provide an ultra-low temperature environment test device that can conveniently replace the sample rod and prevent air leakage. The technical solution is as follows:

[0014] The sample rod is installed on the sample rod cavity through a sealing connection device. The sealing connection device is provided with a sliding sealing cavity away from the sample rod cavity and an air sealing cavity close to the sample rod cavity. The sliding sealing cavity is provided with a sliding sealing cavity evacuation port, and the air sealing cavity is provided with an air sealing cavity evacuation port. A second channel is provided between the sliding sealing cavity and the air sealing cavity. The sliding sealing cavity is provided with a first channel connected to the external atmosphere, and the air sealing cavity is provided with a third channel connected to the sample rod cavity. During the test, the sample rod is inserted into the sample rod cavity through the first channel, the second channel and the third channel in sequence. A first sealing ring device matching the outer diameter of the sample rod is provided on the first channel, a second sealing ring device matching the outer diameter of the sample rod is provided on the second channel, and an isolation valve is provided on the third channel.

[0015] Furthermore, a sliding sealing chamber valve is provided on the sliding sealing chamber evacuation port, an air sealing chamber valve is provided on the air sealing chamber evacuation port, a connecting channel is provided between the sliding sealing chamber valve and the air sealing chamber valve, a vacuum unit evacuation port is provided on the connecting channel, and an air release valve is provided between the vacuum unit evacuation port and the air sealing chamber valve.

[0016] Compared with the prior art, the present invention has the following effects:

[0017] 1) A liquid accumulation chamber and a low-temperature regulating valve are set at the rear end of the first-stage heat exchanger and the second-stage heat exchanger. After the low-temperature helium is throttled and expanded by the temperature regulating valve, it can be cooled to about 1.5K and enter the sample insertion cavity, providing a lower low-temperature environment for the sample.

[0018] 2) A temperature control device is arranged near the secondary cold head, the sample cavity heat exchanger and the sample to facilitate more accurate temperature control.

[0019] 3) The sample rod is installed in the sample rod cavity through a sliding sealing device, which can effectively prevent the entry of external air when the sample rod is replaced. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The present invention provides a composition and connection block diagram of an ultra-low temperature environment test device with inner vacuum.

[0021] Figure 2 Schematic diagrams of four ways of placing the sample rod and the sample in the sample rod cavity.

[0022] Figure 3 It is a structural schematic diagram of the sliding sealing device provided by the present invention. DETAILED DESCRIPTION

[0023] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only examples, and those skilled in the art may think of other obvious variations.

[0024] like Figures 1 to 3 As shown, the inner vacuum ultra-low temperature environment testing device provided by the embodiment of the present invention includes a vacuum chamber 10, a refrigeration device, a helium circulation device, a sample insertion rod 40, a sliding sealing device 70 and a sample insertion rod cavity 30.

[0025] The vacuum chamber 10 is used to provide an internal high vacuum insulation environment. The surface of the vacuum chamber 10 is provided with a vacuum safety valve (not shown in the figure), a superconducting magnet current lead interface (not shown in the figure), a first helium injection port 13, and a vacuum extraction port (not shown in the figure). A vacuum area 19 is formed in the vacuum chamber 10, and the bottom of the vacuum chamber 10 is also provided with anti-slip support feet (not shown in the figure).

[0026] The refrigeration device provides a low-temperature cold source for the vacuum cavity 10, preferably a GM refrigerator or a pulse tube refrigerator. The refrigeration device 20 includes a compressor 21 and a cold head assembly connected to each other. The cold head assembly includes a cold head base 221, and a primary cold head 222 and a secondary cold head 223 extending from the cold head base 221. The cold head base 221 is installed on the vacuum cavity 10, and the primary cold head 222 and the secondary cold head 223 extend into the vacuum area 19 inside the vacuum cavity 10. The compressor 21 is located outside the vacuum cavity 10.

[0027] The sample rod cavity 30 is filled with flowing low-temperature helium for placing the sample rod 40. The sample rod cavity 30 is mounted on the vacuum chamber 10, and includes an insertion portion 31 inserted into the vacuum area 19 in the vacuum chamber 10. A second helium injection port 31a is provided at the bottom of the insertion portion 31. The sample rod cavity 30 is also provided with a helium flow outlet 30b. The insertion portion 31 is thermally connected to the secondary cold head 223 through a pure copper cold conduction belt 32 to absorb cold energy from the refrigeration device 20. A superconducting magnet 33 is installed around the sample rod cavity 30 to provide a magnetic field environment in the sample rod cavity 30.

[0028] The sample rod 40 is used to install and place the sample 50. During measurement, the sample rod 40 and the sample 50 are inserted into the sample rod cavity 30. According to the test requirements of different samples, the way in which the sample rod 40 and the sample 50 are placed in the sample rod cavity 30 is relatively flexible. Figure 2 As shown in a), b), c), and d): Method 1: the sample rod and the sample are both in the flowing helium in the sample rod cavity 30; Method 2: the sample rod is in the flowing helium, and the sample is in the vacuum area; Method 3: the sample rod and the sample are in static helium, and the whole is placed in the flowing helium; Method 4: the sample rod and the sample are in the vacuum area, and the whole is placed in the flowing helium.

[0029] The cryogenic helium circulation device 60 includes a helium storage tank 61, an oil-free dry pump 62 connected to the helium storage tank, an activated carbon filter element 63, a primary heat exchanger 64, a secondary heat exchanger 65, a liquid accumulation chamber 66, a low temperature regulating valve 67, and a sample chamber heat exchanger 68. The activated carbon filter element 63, the primary heat exchanger 64, the secondary heat exchanger 65, the liquid accumulation chamber 66, the low temperature regulating valve 67, and the sample chamber heat exchanger 68 are all installed inside the vacuum chamber 10. A cold shield 70 thermally connected to the primary cold head 222 is installed in the vacuum chamber 10. The cold shield 70 is used to protect the insertion portion 31 of the sample rod cavity 30 and the primary heat exchanger 64, the secondary heat exchanger 65, the low temperature regulating valve 66, and the sample chamber heat exchanger 67 of the cryogenic helium circulation device 60. The primary heat exchanger 64 is thermally connected to the cold shield 70, and the secondary heat exchanger 65 is thermally connected to the secondary cold head 223 through a pure copper belt or a pure copper plate.

[0030] The oil-free dry pump 62 is used to provide circulation power. After the gas helium flowing out of the helium storage tank 61 flows into the vacuum chamber 10 through the first helium injection port 13, it passes through the activated carbon filter element 63 in sequence to filter and absorb other impurity gases (nitrogen / oxygen / carbon dioxide, etc.) to avoid freezing and blocking the pipeline in the lower temperature area; the first-stage heat exchanger 64, and is cooled to about 40K; the second-stage heat exchanger 65 is further cooled to about 4.2K; the liquid accumulating chamber 66, which holds the helium that is cooled and condensed into liquid; the low-temperature regulating valve 66, which is cooled to about 1.5K after throttling expansion; the sample chamber heat exchanger 68, which performs sufficient heat exchange. Afterwards, it is injected into the sample rod cavity 30 through the second helium injection port 31a, and after sufficient heat exchange with the sample rod 40 in the sample rod cavity 30, it flows out from the helium outlet 31b and returns to the storage helium tank 61. From then on, one cycle is completed, and the subsequent cycle continues indefinitely according to this mode.

[0031] Furthermore, in order to achieve precise temperature control of the helium circulating in the vacuum chamber 10, a heater and a temperature sensor (not shown in the figure) are installed near the secondary cold head 223, the sample chamber heat exchanger 67, and the measured sample 50. The heater and the temperature sensor are connected to an external controller (not shown in the figure) to achieve precise temperature control. The use of a heater, a temperature sensor, and a controller for local temperature control is a prior art and will not be described in detail here.

[0032] The present invention further provides a technical solution for flexibly and sealingly disassembling the sample insertion rod.

[0033] like Figure 3As shown, the sample rod 40 is installed on the sample rod cavity 30 through the sealing connection device 70, and the sample end of the sample 50 installed at the end of the sample rod 40 is extended into the sample rod cavity 30. The sealing connection device 70 is provided with a sliding sealing cavity 71 and an air sealing cavity 72 adjacent to each other. The sliding sealing cavity is close to the sample rod cavity, and the air sealing cavity is away from the sample rod cavity. The sliding sealing cavity 71 is provided with a first channel 701 on the side away from the isolation valve 73 for the sample rod 40 to pass through and can be connected to the external atmospheric environment. The adjacent parts of the sliding sealing cavity 71 and the air sealing cavity 72 are provided with a second channel 712 for the sample rod 40 to pass through. The side of the air sealing cavity 72 close to the isolation valve 73 is provided with a third channel 723 for the sample rod 40 to pass through and connected to the sample rod cavity 30. The third channel connects the air sealing cavity 72 and the sample rod cavity 30, and the isolation valve 73 is provided on the channel. During testing, the sample insertion rod 40 is inserted from the external environment into the sample insertion rod cavity 30 through the first channel 701 , the second channel 712 , and the third channel 723 in sequence.

[0034] In order to ensure effective isolation between the external environment and the sealing connection device 70 (specifically, the sliding sealing cavity 71), a first sealing ring device 701a matching the outer diameter of the sample insert rod 40 is provided on the first channel 701. Since it is impossible to achieve absolute sealing, a small amount of external air entering from the gap between the first sealing ring device and the sample insert rod 40 enters the sliding sealing cavity 71. Similarly, in order to ensure effective isolation between the sliding sealing cavity 71 and the air sealing cavity 72, a second sealing ring device 712a matching the outer diameter of the sample insert rod 40 is provided on the second channel 712. In addition, a sliding sealing cavity evacuation port 71a is further provided on the sliding sealing cavity 71, and an air sealing cavity evacuation port 72a is further provided on the air sealing cavity 72. The sliding sealing cavity evacuation port 71a is connected to the vacuum unit evacuation port 73 through the sliding sealing cavity valve 71b, and the air sealing cavity evacuation port 72a is connected to the vacuum unit evacuation port 74 through the air sealing cavity valve 72b. An air release valve 75 is further provided between the air sealing cavity evacuation port 72a and the air sealing cavity valve 72b.

[0035] Based on the sliding sealing device 70 of the above structure, the sample insert 40 is installed in the following steps:

[0036] 1) Connect the external vacuum pump to the vacuum pump port 74, open the sliding seal chamber valve 71a and the air isolation chamber valve 72a, and confirm that the air release valve 75 is in the closed state;

[0037] 2) Turn on the vacuum unit and continue to vacuum for at least 5 minutes;

[0038] 3) Close the air isolation chamber valve 72a, keep the sliding sealing chamber valve in the open state, and slowly move the sample insertion rod 4 downward;

[0039] 4) Open the isolation valve 73 and continue to slowly move the sample rod 40 downward to the working position in the sample rod cavity 30;

[0040] 5) Close the sliding sealing chamber valve 71a, and then close the vacuum unit. At this time, the vacuum unit can be separated from the vacuum unit extraction port.

[0041] When the above-mentioned variable temperature rod device is pulled out of the sample rod cavity and the sample rod and sample are replaced, the following steps are followed:

[0042] 1) Connect the external vacuum pump to the vacuum pump port 74, start the vacuum pump, and then open the sliding seal chamber valve 71a. At this time, confirm that the air isolation chamber valve 72a is in the closed state;

[0043] 2) slowly lift the sample rod 40 so that its bottom leaves the sample rod cavity 30 and close the isolation valve 73;

[0044] 3) Fill a small amount of dry high-purity helium into the air isolation chamber 72a and wait for the sample insert 40 to return to room temperature;

[0045] 4) Close the sliding sealing chamber valve 71a and open the exhaust valve 75 to place the air isolation chamber 72a in an atmospheric state. This completes the entire process of removing the sample rod from the sample chamber.

[0046] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions only describe the principles of the present invention. The present invention may be subject to various changes and improvements without departing from the spirit and scope of the present invention. These changes and improvements fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. An ultra-low temperature environment test device with internal vacuum, characterized in that: include: A vacuum cavity, used to form a vacuum region, and provided with a first helium injection port; A refrigeration device having a primary cold head and a secondary cold head extending into the vacuum region; A sample rod insertion chamber is installed on the vacuum chamber body, comprising an insertion portion inserted into the vacuum region, the insertion portion is provided with a second helium injection port, and the sample rod insertion chamber is also provided with a helium outflow port; A sample rod is used for installing and placing the sample and is inserted into the sample rod cavity during the test; A helium circulation device, comprising a helium storage tank and an oil-free dry pump connected to each other, and also comprising an activated carbon filter element, a primary heat exchanger, a secondary heat exchanger, a liquid accumulation chamber, a low temperature regulating valve, and a sample chamber heat exchanger located in the vacuum region, wherein the primary heat exchanger is thermally connected to the primary cold head, and the secondary heat exchanger is thermally connected to the secondary cold head. Driven by the oil-free dry pump, the helium flowing out of the helium storage tank sequentially flows through the first helium injection port, the activated carbon filter element, the primary heat exchanger, the secondary heat exchanger, the liquid accumulation chamber, the low temperature regulating valve, the sample chamber heat exchanger, the second helium injection port, and the helium outflow port, and then flows back to the helium storage tank; A heater and a temperature sensor are installed near the secondary cold head, the sample chamber heat exchanger and the sample; as well as A temperature controller is communicatively connected with the heater and the temperature sensor.

2. The ultra-low temperature environment test device with inner vacuum according to claim 1, characterized in that: It also includes a cold shield located in the vacuum area and thermally connected to the first-level cold head.

3. The ultra-low temperature environment test device with inner vacuum according to claim 2, characterized in that: A superconducting magnet is installed around the sample rod cavity.

4. The ultra-low temperature environment test device with inner vacuum according to claim 3, characterized in that: The refrigeration device is a GM refrigerator.

5. The ultra-low temperature environment test device with inner vacuum according to any one of claims 1 to 4, characterized in that: The sample insertion rod is installed on the sample insertion rod cavity through a sealing connection device, and the sealing connection device is provided with a sliding sealing cavity away from the sample insertion rod cavity and an air sealing cavity close to the sample insertion rod cavity. The sliding sealing cavity is provided with a sliding sealing cavity evacuation port, and the air sealing cavity is provided with an air sealing cavity evacuation port. A second channel is provided between the sliding sealing cavity and the air sealing cavity, the sliding sealing cavity is provided with a first channel connected to the external atmosphere, and the air sealing cavity is provided with a third channel connected to the sample insertion rod cavity. During the test, the sample insertion rod is inserted into the sample insertion rod cavity through the first channel, the second channel and the third channel in sequence. The first channel is provided with a first sealing ring device matching the outer diameter of the sample insertion rod, the second channel is provided with a second sealing ring device matching the outer diameter of the sample insertion rod, and the third channel is provided with an isolation valve.

6. The ultra-low temperature environment test device with inner vacuum according to claim 5, characterized in that: A sliding sealing chamber valve is provided on the sliding sealing chamber evacuation port, an air sealing chamber valve is provided on the air sealing chamber evacuation port, a connecting channel is provided between the sliding sealing chamber valve and the air sealing chamber valve, a vacuum unit extraction port is provided on the connecting channel, and an air release valve is provided between the vacuum unit extraction port and the air sealing chamber valve.

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