Multi-channel automated Hall effect test system

Abstract

In the field of Hall effect testing technology, the present application provides a multi-channel automated Hall effect testing system, which includes a rack, a displacement mechanism, a sample testing mechanism and a liquid nitrogen storage unit; the displacement mechanism is installed on the rack; the sample testing mechanism includes a sample rod and a sample card, one end of the sample rod is connected to the displacement mechanism, and the displacement mechanism is used to drive the sample rod to move relative to the rack; the sample card is connected to the end of the sample rod away from the displacement mechanism, and the sample card is used to install the sample; the liquid nitrogen storage unit is installed on the rack, and the liquid nitrogen storage unit has a storage tank, and the storage tank is used to place liquid nitrogen; a first vacuum chamber is opened inside the side wall of the liquid nitrogen storage unit, and the first vacuum chamber is arranged around the circumference of the storage unit; a second vacuum chamber is opened inside the bottom wall of the liquid nitrogen storage unit. The present application has the effect of slowing down the volatilization rate of liquid nitrogen in the liquid nitrogen storage tank, thereby extending the time that the same amount of liquid nitrogen can maintain a low-temperature environment.

Description

Technical Field

[0001] The present application relates to the field of Hall effect testing technology, and in particular to a multi-channel automated Hall effect testing system. Background Art

[0002] The multi-channel automated Hall test system can perform rapid and automatic testing on various types of samples such as multi-electrode cylindrical ingots, D-type ingots and wafers in an electromagnetic field and liquid nitrogen low-temperature environment (77K) to obtain the Hall parameters of the samples, including the resistivity, Hall coefficient, Hall voltage, carrier concentration, Hall mobility and carrier type of the samples to be tested.

[0003] When performing a Hall test, you need to first add liquid nitrogen to the liquid nitrogen storage tank to create a low-temperature environment, and then insert the sample to be tested into the liquid nitrogen storage tank for testing.

[0004] The boiling point of liquid nitrogen is -196°C (some say -195.8°C), and it is very easy to volatilize at room temperature and pressure. During the Hall test, for a single sample to be tested, it is necessary to replace multiple channels for parameter testing; after completing the test of one sample, it is necessary to replace a new sample to continue the multi-channel test. During the above-mentioned process of replacing multiple channels and replacing samples, the liquid nitrogen in the liquid nitrogen storage tank will be in a state of continuous volatilization. Although the volatilization process will help to form a low-temperature environment due to heat absorption, it will also accelerate the loss of liquid nitrogen in the liquid nitrogen storage tank, which is not conducive to maintaining a low-temperature environment for a long time. Summary of the invention

[0005] In order to prolong the time that the low-temperature environment can be maintained with the same amount of liquid nitrogen by slowing down the volatilization rate of liquid nitrogen in the liquid nitrogen storage tank, the present application provides a multi-channel automated Hall effect testing system.

[0006] The multi-channel automated Hall effect test system provided by the present application adopts the following technical solution: A multi-channel automated Hall effect test system comprises a frame, a displacement mechanism, a sample testing mechanism and a liquid nitrogen storage element; the displacement mechanism is mounted on the frame; the sample testing mechanism comprises a sample rod and a sample card, one end of the sample rod is connected to the displacement mechanism, and the displacement mechanism is used to drive the sample rod to move relative to the frame; the sample card is connected to one end of the sample rod away from the displacement mechanism, and the sample card is used to install a sample; a liquid nitrogen storage element is mounted on the frame, the liquid nitrogen storage element has a storage slot, and the storage slot is used to place liquid nitrogen; a first vacuum cavity is opened inside the side wall of the liquid nitrogen storage element, and the first vacuum cavity is arranged around the circumference of the storage element; a second vacuum cavity is opened inside the bottom wall of the liquid nitrogen storage element.

[0007] By adopting the above technical solution, during the test, first load liquid nitrogen into the storage tank of the liquid nitrogen storage component to create a low-temperature environment; at the same time, install the sample on the sample card, and then use the displacement mechanism to drive the sample card to move and send the sample into the storage tank of the liquid nitrogen storage component. After the test is completed, use the displacement mechanism to move the sample back to the original installation position of the sample, and replace it with a new sample to be tested. During the entire test process above, the first vacuum chamber and the second vacuum chamber are used to form a certain insulation for the heat conduction inside and outside the storage tank, reducing the influence of the external ambient temperature on the internal temperature of the storage tank, thereby slowing down the volatilization rate of the liquid nitrogen during the test process, extending the time that the same amount of liquid nitrogen can maintain a low-temperature environment, and reducing the consumption rate of liquid nitrogen in the storage tank.

[0008] Optionally, the liquid nitrogen storage component is provided with a cover body, which is used to cover the opening of the storage component; the cover body includes a first cover, a second cover and an elastic member, the first cover and the second cover are both connected to the storage component along the width direction of the storage component, and a gap for the sample card to pass through can be formed between the first cover and the second cover; the elastic member is used to force the first cover and the second cover to abut against each other; the sample card includes a card body and a guide bar, the upper end of the guide bar is connected to the upper end of the card body, the lower end of the guide bar is connected to the lower end of the card body, and the guide bar is arranged in an arch shape on the card body; the guide bars are provided in multiple groups, the number of the guide bars in each group is two, and the two guide bars are respectively connected to two surfaces of the sample card that are opposite to each other; the multiple groups of guide bars are arranged at intervals along the width direction of the sample card.

[0009] By adopting the above technical solution, a cover body is added to the upper end of the liquid nitrogen storage element, and the cover body is used at the opening of the storage tank to further isolate the heat conduction inside and outside the storage tank, thereby further improving the utilization rate of liquid nitrogen.

[0010] During the test, the sample card and the sample are driven by the displacement mechanism to move downward toward the liquid nitrogen storage element. When the sample card moves to the position of the cover body, the first cover and the second cover first move away from each other under the support of the arched guide strip. After the sample enters the storage slot, the first cover and the second cover move closer to each other again under the action of the elastic member and cover the notch of the storage slot.

[0011] Optionally, the first cover is provided with a third vacuum chamber, and the second cover is provided with a fourth vacuum chamber.

[0012] By adopting the above technical solution and arranging the third vacuum chamber and the fourth vacuum chamber on the cover body, the heat conduction inside and outside the storage tank is further isolated, thereby improving the utilization rate of liquid nitrogen.

[0013] Optionally, a first groove is formed on a side wall of the first cover close to the second cover, and a second groove is formed on a side wall of the second cover close to the first cover. The first groove and the second groove are combined to form a penetration cavity for the sample rod to penetrate.

[0014] By adopting the above technical solution, after the sample is inserted into the storage tank, the first cover and the second cover except the first groove and the second groove abut against each other, so that the cover body can cover the groove of the storage tank to the greatest extent, so as to further ensure the utilization rate of liquid nitrogen.

[0015] Optionally, the cover body further includes a connecting piece, and the connecting piece is slidably connected to the liquid nitrogen storage piece along a height direction of the liquid nitrogen storage piece; the first cover and the second cover are both connected to the connecting piece.

[0016] By adopting the above technical solution, under normal conditions, the connector and the cover body abut against the upper end surface of the liquid nitrogen storage element under the action of their own gravity, and after a large amount of liquid nitrogen in the storage tank evaporates to form nitrogen gas, the volume increases significantly, resulting in an increase in the gas pressure in the storage tank. In the case where a connector that can slide relative to the liquid nitrogen storage element is provided, when the gas pressure increases to a certain extent, an upward force is applied to the cover body, thereby increasing the storage space of the storage tank and avoiding safety accidents.

[0017] Optionally, the cover body is provided with a first ventilation tube, one end of which extends into the storage tank; the other end is connected to a recovery airbag, and the lumen of the first ventilation tube is communicated with the inner lumen of the recovery airbag.

[0018] By adopting the above technical solution, the nitrogen formed after the liquid nitrogen is gasified can enter the recovery airbag through the first ventilation pipe, so that the recovery airbag can be used to recover and store the nitrogen, thereby reducing the occurrence of safety accidents and recycling the nitrogen.

[0019] Optionally, the recovery airbag jacket is provided with a rigid safety can, and the outer wall of the recovery airbag and the inner wall of the safety can are connected by an elastic rope.

[0020] By adopting the above technical solution, on the one hand, the recovery airbag is supported by the safety tank, which is convenient for the installation of the recovery airbag; on the other hand, the recovery airbag is also protected to a certain extent to avoid safety accidents or damage to the recovery airbag.

[0021] Optionally, the safety tank is provided with a second ventilation pipe, the lumen of the second ventilation pipe is connected to the inner cavity of the safety tank, and one end of the second ventilation pipe away from the safety tank is connected to a vacuum pump; the first ventilation pipe is provided with a valve.

[0022] By adopting the above technical solution, during the test, the gas in the safety tank is first extracted by a vacuum pump, so that the air pressure in the safety tank is reduced, and then the air pressure in the recovery airbag is reduced. Then the valve is opened to connect the inner cavity of the recovery airbag with the storage tank. The liquid nitrogen in the storage tank is vaporized to form nitrogen gas, which enters the recovery airbag through the first ventilation pipe under the action of the air pressure difference, so that the vaporized nitrogen gas is recovered.

[0023] Before the liquid nitrogen is completely vaporized, the valve is always kept in an open state, and the air pressure in the storage tank is always kept greater than the air pressure in the recovery air bag by adjusting the vacuum pump, so that the nitrogen can smoothly pass through the first ventilation pipe into the recovery air bag.

[0024] After the liquid nitrogen is completely gasified, close the valve. Before the next test, introduce gas into the safety tank through the vacuum pump to apply high pressure to the nitrogen in the recovery airbag, so that the nitrogen is re-liquefied to form liquid nitrogen. Open the valve before the test to allow the liquid nitrogen to flow into the storage tank through the first ventilation pipe, so that the liquid nitrogen can be recycled.

[0025] Optionally, a gas collecting piece is provided at the end of the first ventilation tube away from the recovery airbag, the gas collecting piece is made of silicone, the gas collecting piece has a gas collecting port, the gas collecting port is connected to the tube cavity of the first ventilation tube, and the diameter of the gas collecting port is larger than the inner diameter of the first ventilation tube.

[0026] By adopting the above technical solution, the gas collecting member provided with the gas collecting port is used to form a certain flow guiding effect on the nitrogen, so that more nitrogen can flow into the first ventilation pipe, thereby improving the recovery and utilization rate of the nitrogen.

[0027] Optionally, the connection point between the first ventilation tube and the recovery airbag is located on the bottom wall of the recovery airbag.

[0028] By adopting the above technical solution, liquid nitrogen can flow from the first ventilation pipe to the storage tank under the action of its own gravity without the need for a separate conveying structure.

[0029] In summary, the present application includes at least one of the following beneficial technical effects: 1. By setting a first vacuum cavity on the side wall of the liquid nitrogen storage unit and a second vacuum cavity on the bottom wall of the liquid nitrogen storage unit, the first vacuum cavity and the second vacuum cavity are used to form a certain degree of insulation for the heat conduction inside and outside the storage tank, thereby slowing down the volatilization rate of the liquid nitrogen in the liquid nitrogen storage tank, prolonging the time that the same amount of liquid nitrogen can maintain a low-temperature environment, and improving the utilization rate of liquid nitrogen; 2. By providing a cover body on the liquid nitrogen storage unit, and making the cover body include a first cover and a second cover, when the sample card and the sample enter the storage slot, under the support of the guide bar, the first cover and the second cover are separated from each other, which is convenient for the sample card and the sample to enter the storage slot. During the test, the first cover and the second cover cover the notch of the storage slot, and the first cover is provided with a third vacuum chamber, and the second cover is provided with a fourth vacuum chamber, so that the heat conduction inside and outside the storage slot is isolated at the notch of the storage slot to further improve the utilization rate of liquid nitrogen; 3. The recovery airbag is connected to the storage tank through a first ventilation pipe, which is provided with a valve, and a safety tank is provided outside the recovery airbag, and a vacuum pump is provided on the safety tank. During the test, the gas in the safety tank is extracted by the vacuum pump to create an air pressure difference between the recovery airbag and the storage tank, so that nitrogen can enter the recovery airbag. Before the test, the valve is closed, gas is introduced into the safety tank, and pressure is applied to the recovery airbag to liquefy the nitrogen under high pressure, so as to facilitate the recovery and utilization of nitrogen and improve the utilization rate of nitrogen. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the overall structure of Example 1 of the present application.

[0031] Figure 2 It is a schematic diagram for showing the structure of the liquid nitrogen storage component in Example 1.

[0032] Figure 3 It is a schematic diagram for showing the structure of the detachable connection between the sample card and the sample rod in Example 1.

[0033] Figure 4 It is a structural diagram of Example 2 of the present application.

[0034] Figure 5 It is a schematic diagram for showing the structure of the first groove and the second groove in Example 2.

[0035] Figure 6 It is a structural diagram of Example 3 of the present application.

[0036] Figure 7 It is a structural diagram of Example 4 of the present application.

[0037] Description of reference numerals: 1, frame; 2, displacement mechanism; 21, motor bracket; 22, Z-axis servo stepper motor; 23, X-axis servo stepper motor; 3, sample testing mechanism; 31, junction box bracket; 32, junction box; 33, sample rod; 331, plug-in slot; 34, sample card; 341, plug-in block; 342, card body; 343, guide bar; 4, liquid nitrogen storage element; 41, storage slot; 42, first vacuum chamber; 43, second vacuum chamber; 44, penetration hole; 45, sliding slot; 5, cover body; 51. First cover; 511. Third vacuum chamber; 512. First groove; 52. Second cover; 521. Fourth vacuum chamber; 522. Second groove; 53. Elastic member; 54. Moving rod; 55. Connecting member; 551. Air vent; 6. Safety can; 61. Mounting tube; 611. Ventilation part; 612. Compression part; 613. Ventilation chamber; 62. Recovery air bag; 63. Second ventilation pipe; 64. Vacuum pump; 65. First ventilation pipe; 651. Valve; 66. Gas collecting member; 661. Gas collecting port. DETAILED DESCRIPTION

[0038] The embodiment of the present application discloses a multi-channel automated Hall effect testing system.

[0039] Example 1 Reference Figure 1 The multi-channel automated Hall effect test system includes a rack 1, a matrix switch, an electromagnet assembly, a displacement mechanism 2, a sample testing mechanism 3 and a liquid nitrogen storage unit 4.

[0040] The matrix switch realizes the electrode switching and connection of the sample through the system software programmable PCI matrix switch. It adopts a 4-channel design, and each channel adopts a 1-cut 16-way design, that is, each channel can select any one of the 16 lines, so that the test system can test the four lines corresponding to the four channels, and after completing a set of tests, the system will automatically switch the four channels to different lines and carry out the next test.

[0041] The electromagnet assembly includes an electromagnet, an electromagnet bracket, an electromagnet power supply, a Gauss meter and a probe. The electromagnet is mounted on the electromagnet bracket, and the electromagnet bracket is mounted on the frame 1. The electromagnet provides a stable and uniform magnetic field for the sample. The Gauss meter and the probe are used to measure the magnitude of the magnetic field strength in the central area of ​​the electromagnet, that is, to measure the actual magnetic field magnitude in the central area of ​​the electromagnet.

[0042] The displacement mechanism 2 includes a motor bracket 21, a Z-axis servo stepper motor 22 and an X-axis servo stepper motor 23. The motor bracket 21 is installed on the frame 1, the Z-axis servo stepper motor 22 is installed on the motor bracket 21, and the X-axis servo stepper motor 23 is installed on the output end of the Z-axis servo stepper motor 22.

[0043] The sample testing mechanism 3 includes a junction box bracket 31, a junction box 32, a sample rod 33, a sample card 34 and a triaxial cable. The junction box 32 is connected to the output end of the X-axis servo stepper motor 23, the sample rod 33 is connected to the bottom of the junction box 32, the sample card 34 is connected to the end of the sample rod 33 away from the junction box 32, and the sample card 34 is used for sample installation. The triaxial cable is connected to the matrix switch through the junction box 32.

[0044] The sample card 34 is detachably connected to the sample rod 33, so that the sample card 34 that can be installed with different samples can be easily replaced according to the shape of the sample and the distribution of electrodes.

[0045] Reference Figure 1 and Figure 2 The liquid nitrogen storage unit 4 is installed on the rack 1. The liquid nitrogen storage unit 4 has a storage tank 41 for storing liquid nitrogen. A first vacuum chamber 42 is provided inside the side wall of the storage unit. The first vacuum chamber 42 is also provided along the circumference of the storage unit. A second vacuum chamber 43 is provided inside the bottom wall of the storage unit. The first vacuum chamber 42 and the second vacuum chamber 43 are used to isolate the temperature in the storage tank 41 from the ambient temperature outside, reduce the heat conduction of the outside air to the liquid nitrogen in the storage tank 41, and reduce the influence of the ambient temperature outside on the internal temperature of the storage tank 41, thereby slowing down the volatilization speed of the liquid nitrogen in the storage tank 41, prolonging the time that the same amount of liquid nitrogen can maintain a low-temperature environment, and reducing the consumption rate of the liquid nitrogen in the storage tank 41.

[0046] Reference Figure 3 In this embodiment, the specific structure of the detachable connection is as follows: the sample card 34 has a plug-in block 341, the sample rod 33 has a plug-in slot 331 for the plug-in block 341 to be plugged in, and the sample card 34 and the sample rod 33 are connected by the matching damping of the plug-in block 341 and the plug-in slot 331. In other embodiments, the sample card 34 and the sample rod 33 can also be detachably connected by other quick-release structures, as long as a stable connection between the sample card 34 and the sample rod 33 is ensured.

[0047] The implementation principle of Example 1 is as follows: when testing, the sample is first installed: first, a sample card 34 corresponding to the sample is selected; then, the sample electrode is connected to the electrode of the sample card 34 by welding wire, and the sample is fixed to the sample card 34 with a low-temperature tape to prevent the sample from shaking on the sample card 34; then, the front of the sample card 34 is facing the S pole of the electromagnet, and the sample card 34 is connected to the sample rod 33.

[0048] Then, the sample card 34 and the sample are transferred to the storage slot 41 for testing by using the displacement mechanism 2. After the test of the sample card 34 is completed, the sample card 34 and the sample are driven back to the position where the sample is installed by using the displacement mechanism 2. Then, the sample that has been tested and the corresponding sample card 34 are removed, and the sample card 34 with a new sample to be tested is replaced. It should be noted that if the test is performed at a low temperature of 77K, it is necessary to wait for the sample card 34 and the sample to return to room temperature before removing the sample card 34 from the sample card 34 slot.

[0049] After all the tests are completed, just wait for the liquid nitrogen in the liquid nitrogen storage unit 4 to evaporate naturally.

[0050] Example 2 Reference Figure 4 The difference between this embodiment and embodiment 1 is that the liquid nitrogen storage element 4 is provided with a cover 5, and the cover 5 is used to cover the opening of the storage element, so that the cover 5 is used to isolate the temperature inside and outside the storage tank 41 at the opening of the liquid nitrogen storage element 4, thereby further reducing heat conduction.

[0051] Specifically, the cover body 5 includes a first cover 51, a second cover 52, an elastic member 53 and a connecting member 55. The first cover 51 and the second cover 52 are both slidably connected to the upper wall of the storage member along the width direction of the storage member. After the first cover 51 and the second cover 52 move away from each other, a gap for the sample card 34 to pass through can be formed between the first cover 51 and the second cover 52. The elastic member 53 is used to force the first cover 51 and the second cover 52 to abut against each other.

[0052] The specific structure of the first cover 51, the second cover 52 and the elastic member 53 is as follows: take the first cover 51 as an example, and the second cover 52 can be obtained in the same way. The cross-section of the first cover 51 is an inverted U-shape, and the first cover 51 is fixedly connected to the moving rod 54, and the two ends of the moving rod 54 are respectively connected to the two opposite side walls of the first cover 51. The side wall of the liquid nitrogen storage component 4 is penetrated by a hole 44 for the moving rod 54 to pass through. The elastic member 53 is a spring, and the elastic member 53 is sleeved outside the moving rod 54. One end of the elastic member 53 abuts against the side wall of the first cover 51 close to the second cover 52, and the other end abuts against the inner wall of the liquid nitrogen storage component 4. Under normal conditions, the elastic member 53 is in a compressed state.

[0053] The sample card 34 includes a card body 342 and a guide bar 343 . The upper end of the guide bar 343 is connected to the upper end of the card body 342 , and the lower end of the guide bar 343 is connected to the lower end of the card body 342 . The guide bar 343 is arranged in an arch shape on the card body 342 .

[0054] In this embodiment, two groups of guide bars 343 are provided. Each group of guide bars 343 has two guide bars 343, and the two guide bars 343 are respectively connected to two surfaces of the sample card 34 that are away from each other. The two groups of guide bars 343 are arranged at intervals along the width direction of the sample card 34.

[0055] In the process of inserting the sample card 34 into the storage slot 41, the first cover 51 and the second cover 52 are supported by the guide bar 343 of the arched guide bar 343 to open the cover body 5, so that the first cover 51 and the second cover 52 are first separated from each other and then gradually approach each other, thereby forming a certain isolation between the storage slot 41 and the outside, further isolating the heat conduction inside and outside the storage slot 41, and improving the utilization rate of liquid nitrogen.

[0056] In other embodiments, more groups of guide bars 343 may be provided.

[0057] Furthermore, the first cover 51 defines a third vacuum chamber 511 , and the second cover 52 defines a fourth vacuum chamber 521 , so as to further isolate the heat conduction between the inside and the outside of the storage tank 41 .

[0058] Reference Figure 5 In order to adapt to the sample rod 33, a first groove 512 is opened on the side wall of the first cover 51 close to the second cover 52, and a second groove 522 is opened on the side wall of the second cover 52 close to the first cover 51. The first groove 512 and the second groove 522 are combined to form a penetration cavity for the sample rod 33 to penetrate.

[0059] Example 3 Reference Figure 6 The difference between this embodiment and embodiment 2 is that, in this embodiment, the cover body 5 further includes a connecting member 55, which is a cylindrical structure, and the central axis of the connecting member 55 is colinear with the central axis of the liquid nitrogen storage member 4. The upper end surface of the liquid nitrogen storage member 4 is provided with a sliding groove 45 for inserting the connecting member 55, so that the connecting member 55 is slidably connected to the liquid nitrogen storage member 4 along the height direction of the liquid nitrogen storage member 4.

[0060] In this embodiment, the through hole 44 is formed through the side wall of the connecting member 55 , so that both the first cover 51 and the second cover 52 are connected to the connecting member 55 .

[0061] The connecting member 55 has a plurality of air outlet holes 551 formed therethrough. The plurality of air outlet holes 551 are evenly distributed on the connecting member 55 .

[0062] Under normal conditions, the connector 55 and the cover 5 abut against the upper end surface of the liquid nitrogen storage element 4 under the action of their own gravity, and after a large amount of liquid nitrogen in the storage tank 41 evaporates to form nitrogen gas, the volume increases greatly, resulting in an increase in the gas pressure in the storage tank 41. In the case where a connector 55 that can slide relative to the liquid nitrogen storage element 4 is provided, when the gas pressure increases to a certain extent, an upward force is applied to the cover 5, thereby increasing the storage space of the storage tank 41 and avoiding safety accidents.

[0063] Furthermore, a plurality of vent holes are formed through the side wall of the connector 55 so that when the volume of nitrogen is too large, it can be discharged from the vent holes, thereby further ensuring safety.

[0064] Example 4 Reference Figure 7 The difference between this embodiment and the embodiment 1 is that the frame 1 is provided with a safety tank 6 made of a rigid material. The safety tank 6 is provided with a mounting tube 61, one end of which is fixedly connected to the top wall of the safety tank 6. The mounting tube 61 is provided with a recovery air bag 62, and a part of the surface of the recovery air bag 62 is bonded and fixed to the bottom wall of the mounting tube 61.

[0065] The mounting tube 61 includes a vent portion 611 and a compression portion 612. One end of the vent portion 611 is used to connect with the safety can 6, and the compression portion 612 is connected to the other end of the vent portion 611. The vent portion 611 is penetrated by a plurality of vent cavities 613, which extend along the length direction of the vent portion 611 and are arranged at intervals around the central axis of the vent portion 611.

[0066] A piston is provided in the installation cylinder 61, and the side wall of the piston abuts against the cylinder wall of the installation cylinder 61. The recovery air bag 62 is located between the piston and the bottom wall of the installation cylinder 61. A pressure rod is connected to the surface of the piston away from the recovery air bag 62, and the pressure rod extends outside the safety tank 6. The frame 1 is provided with a hydraulic cylinder, and the output end of the hydraulic cylinder is connected to the pressure rod, and the hydraulic cylinder is used to drive the pressure rod to move along the length direction of the installation cylinder 61.

[0067] The safety tank 6 is connected to a second ventilation pipe 63 , the lumen of the second ventilation pipe 63 is in communication with the inner lumen of the safety tank 6 , and one end of the second ventilation pipe 63 away from the safety tank 6 is connected to a vacuum pump 64 .

[0068] The recovery air bag 62 is provided with a first vent pipe 65, and one end of the first vent pipe 65 away from the recovery air bag 62 is connected to the cover body 5 and extends into the storage tank 41. The first vent pipe 65 is provided with a valve 651.

[0069] During the test, the vacuum pump 64 is first used to extract the gas in the safety tank 6, so that the air pressure in the safety tank 6 is reduced, and then the air pressure in the recovery airbag 62 is reduced. Then the valve 651 is opened to connect the inner cavity of the recovery airbag 62 with the storage tank 41. The liquid nitrogen in the storage tank 41 is vaporized to form nitrogen gas, and the nitrogen gas enters the recovery airbag 62 through the first ventilation pipe 65 under the action of the air pressure difference, so that the vaporized nitrogen gas is recovered.

[0070] Before the liquid nitrogen is completely vaporized, the valve 651 is always kept in an open state, and the air pressure in the storage tank 41 is always kept greater than the air pressure in the recovery air bag 62 by adjusting the vacuum pump 64, so that the nitrogen can smoothly pass through the first ventilation pipe 65 into the recovery air bag 62.

[0071] After the liquid nitrogen is completely gasified, close the valve 651. Before the next test, gas is introduced into the safety tank 6 through the vacuum pump 64 to apply high pressure to the nitrogen in the recovery airbag 62. After the recovery airbag 62 is completely pressed into the compression part 612, while continuing to ventilate the safety tank 6, start the hydraulic cylinder, drive the piston and apply pressure to the recovery airbag 62, so that the nitrogen is re-liquefied to form liquid nitrogen. Open the valve 651 before the test to allow the liquid nitrogen to flow into the storage tank 41 through the first ventilation pipe 65, so that the liquid nitrogen is recycled.

[0072] In this embodiment, the safety tank 6 is arranged at a position higher than the position of the liquid nitrogen storage tank 41, and the connection point between the first ventilation pipe 65 and the recovery airbag 62 is located at the bottom wall of the recovery airbag 62, so that the liquid nitrogen can flow from the first ventilation pipe 65 into the storage tank 41 under the action of its own gravity.

[0073] Furthermore, a gas collecting piece 66 is provided at the end of the first ventilation tube 65 away from the recovery airbag 62. The gas collecting piece 66 is made of silicone and has a gas collecting port 661 connected to the tube cavity of the first ventilation tube 65. The diameter of the gas collecting port 661 is larger than the inner diameter of the first ventilation tube 65. The gas collecting piece 66 with the gas collecting port 661 can form a certain diversion effect on the nitrogen, so that more nitrogen can flow into the first ventilation tube 65, thereby improving the recovery and utilization rate of the nitrogen.

[0074] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A multi-channel automated Hall effect test system, characterized in that: The invention comprises a frame (1), a displacement mechanism (2), a sample testing mechanism (3) and a liquid nitrogen storage element (4); the displacement mechanism (2) is mounted on the frame (1); the sample testing mechanism (3) comprises a sample rod (33) and a sample card (34); one end of the sample rod (33) is connected to the displacement mechanism (2), and the displacement mechanism (2) is used to drive the sample rod (33) to move relative to the frame (1); the sample card (34) is connected to an end of the sample rod (33) away from the displacement mechanism (2), and the sample card (34) is used to mount a sample; the liquid nitrogen storage element (4) is mounted on the frame (1), the liquid nitrogen storage element (4) has a storage groove (41), and the storage groove (41) is used to place liquid nitrogen; a first vacuum cavity (42) is provided inside a side wall of the storage element, and the first vacuum cavity (42) is arranged around the circumference of the storage element; a second vacuum cavity (43) is provided inside a bottom wall of the storage element.

2. A multi-channel automated Hall effect test system according to claim 1, characterized in that: The liquid nitrogen storage element (4) is provided with a cover body (5), and the cover body (5) is used to cover the opening of the storage element; the cover body (5) comprises a first cover (51), a second cover (52) and an elastic member (53); the first cover (51) and the second cover (52) are both slidably connected to the storage element along the width direction of the storage element, and a gap for the sample card (34) to pass through can be formed between the first cover (51) and the second cover (52); the elastic member (53) is used to force the first cover (51) and the second cover (52) to abut against each other; the sample card (34) comprises a card The card body (342) comprises a card body (342) and a guide bar (343), wherein the upper end of the guide bar (343) is connected to the upper end of the card body (342), and the lower end of the guide bar (343) is connected to the lower end of the card body (342), and the guide bar (343) is arranged in an arch shape on the card body (342); a plurality of groups of the guide bars (343) are arranged, and each group of the guide bars (343) comprises two guide bars, and the two guide bars (343) are respectively connected to two surfaces of the sample card (34) that are away from each other; and the plurality of groups of the guide bars (343) are arranged at intervals along the width direction of the sample card (34).

3. A multi-channel automated Hall effect test system according to claim 2, characterized in that: The first cover (51) is provided with a third vacuum chamber (511), and the second cover (52) is provided with a fourth vacuum chamber (521).

4. A multi-channel automated Hall effect test system according to claim 2, characterized in that: A first groove (512) is formed on a side wall of the first cover (51) close to the second cover (52), and a second groove (522) is formed on a side wall of the second cover (52) close to the first cover (51). The first groove (512) and the second groove (522) are combined to form a penetration cavity for the sample rod (33) to penetrate.

5. A multi-channel automated Hall effect test system according to claim 2, characterized in that: The cover body (5) further comprises a connecting piece (55), wherein the connecting piece (55) is slidably connected to the liquid nitrogen storage piece (4) along a height direction of the liquid nitrogen storage piece (4); the first cover (51) and the second cover (52) are both connected to the connecting piece (55).

6. A multi-channel automated Hall effect test system according to claim 2, characterized in that: The cover body (5) is provided with a first ventilation tube (65), one end of the first ventilation tube (65) extends into the storage tank (41), the other end of the first ventilation tube (65) is connected to the recovery airbag (62), and the lumen of the first ventilation tube (65) is in communication with the inner lumen of the recovery airbag (62).

7. A multi-channel automated Hall effect test system according to claim 6, characterized in that: The outer shell of the recovery airbag (62) is provided with a safety can (6) made of a rigid material.

8. A multi-channel automated Hall effect test system according to claim 7, characterized in that: The safety tank (6) is provided with a second ventilation pipe (63), the lumen of the second ventilation pipe (63) is in communication with the inner lumen of the safety tank (6), and one end of the second ventilation pipe (63) away from the safety tank (6) is connected to a vacuum pump (64); the first ventilation pipe (65) is provided with a valve (651).

9. A multi-channel automated Hall effect test system according to claim 6, characterized in that: An air collecting piece (66) is provided at the end of the first ventilation tube (65) away from the recovery air bag (62); the air collecting piece (66) is made of silicone; the air collecting piece (66) is provided with an air collecting port (661); the air collecting port (661) is connected to the tube cavity of the first ventilation tube (65); the diameter of the air collecting port (661) is larger than the inner diameter of the first ventilation tube (65).

10. A multi-channel automated Hall effect test system according to claim 8, characterized in that: The connection point between the first ventilation tube (65) and the recovery airbag (62) is located on the bottom wall of the recovery airbag (62).

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