Experimental device for ultra-low-temperature Paschen discharge and cooling method

Abstract

The invention provides an experimental device for very low temperature Paschen discharge and a cooling method, and relates to the technical field of very low temperature Paschen power generation experiments, the experimental device comprises a vacuum container and a low temperature Dewar for accommodating the vacuum container, and the low temperature Dewar can accommodate a cold source located outside the vacuum container. The vacuum container is respectively connected with a vacuum pump set and a helium supply device outside the low-temperature Dewar through pipelines, and valves are arranged on the pipelines; the vacuum pump set is adopted to pump out gas in the vacuum container and vacuumize the vacuum container, meanwhile, the helium supply device adjusts helium output pressure and controls pressure in the vacuum container through a valve, and helium serves as a medium in the vacuum container, so that the cooling rate of the vacuum container in the low-temperature Dewar is increased, and the vacuum container is cooled. Therefore, the temperature zone and the pressure intensity of the vacuum container can meet the low-temperature Paschen discharge experiment.

Description

Technical Field

[0001] The present invention relates to the technical field of ultra-low temperature Paschen power generation experiments, and in particular to an experimental device and a cooling method for ultra-low temperature Paschen discharge. Background Art

[0002] As an important new energy source in the future, the research and development of controlled nuclear fusion has always attracted the attention of the public and various industries. The insulating materials used in fusion superconducting magnet technology need to withstand low temperature, high pressure and hot and cold cycles. In addition, the high-voltage insulating materials in the fast-controlled magnet coils especially need good low-temperature performance. If insulation defects and vacuum leaks are produced during processing and manufacturing, it is very easy to cause Paschen power generation accidents in a high-current operation environment.

[0003] Paschen's law defines the breakdown voltage of different gases under different vacuum conditions. It mainly shows through the V-Pd curve that any gas has a Paschen discharge minimum point. Once the gas pressure and electrode distance that meet the minimum point are reached, the gas will break down at a very low voltage.

[0004] In fact, the insulating materials in superconducting magnet technology are in an extremely low temperature (4.2K) environment, and their insulation performance is poor due to the strong permeability of liquid helium and poor voltage resistance. Therefore, the insulating materials of superconducting magnets must have a certain compressive strength and anti-surface discharge capability. In addition, the mechanical properties should have sufficient mechanical strength and plasticity to withstand the huge electromagnetic force of the superconducting magnet, and after multiple hot and cold cycles, they still have the required dielectric and mechanical properties.

[0005] The existing technology is mainly aimed at Paschen discharge testing at room temperature, and there are very few Paschen discharge experimental studies on superconducting electrical applications. Since the environment of superconducting applications must be in liquid nitrogen (77K) and liquid helium (4.2K), Paschen discharge experimental studies on superconducting conductor insulating materials in extremely low temperature environments are carried out. There are a few Paschen discharge experiments on superconducting conductor insulating materials that can be carried out in low temperature environments. The experimental equipment is usually immersed in liquid nitrogen to achieve a low temperature environment. This method is simple and low in cost, but it is necessary to ensure the continuous supply of liquid nitrogen and safe operation. The temperature zone of the experimental equipment is difficult to control within the range required for the experiment. The present invention has made improvements in this regard.

[0006] The purpose of the present invention is to provide an experimental device and a cooling method for ultra-low temperature Paschen discharge. The device is used to carry out Paschen discharge experiments on insulating materials in superconducting magnet technology, provide test conditions for ultra-low temperature Paschen discharge experiments, and provide technical support for solving the insulation treatment process for ultra-low temperature superconducting applications. Summary of the invention

[0007] The present invention provides an experimental device for extremely low temperature Paschen discharge and a cooling method, aiming to solve the technical problem that the Paschen discharge experiment of superconducting conductor insulating materials in the current low temperature environment cannot achieve good temperature zone control.

[0008] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0009] An experimental device for extremely low temperature Paschen discharge comprises a vacuum container and a low temperature Dewar accommodating the vacuum container. The vacuum container is connected to a vacuum pump group and a helium supply device outside the low temperature Dewar through pipelines, and valves are arranged on the pipelines. The low temperature Dewar can accommodate a cold source located outside the vacuum container.

[0010] Preferably, the pipeline includes a main pipeline and two branch pipelines connected to the main pipeline, the end of the main pipeline is connected to the vacuum container, the ends of the two branch pipelines are respectively connected to the helium supply device and the vacuum pump group, and are respectively provided with a vacuum valve four and a vacuum valve three.

[0011] Preferably, a second vacuum valve is provided on the main pipe.

[0012] Preferably, a pressure gauge and a pressure dividing valve are provided on the branch pipeline connected to the helium supply device.

[0013] Preferably, the vacuum container tube is connected to a temperature monitor and a vacuum gauge located outside the cryogenic Dewar.

[0014] Preferably, the cold source comprises liquid nitrogen or liquid helium.

[0015] Preferably, a pipeline connecting the vacuum gauge and the vacuum container is provided with a vacuum valve 1.

[0016] According to the above-mentioned cooling method for the experimental device for extremely low temperature Paschen discharge, the following steps are included:

[0017] S1: In the initial state, the valve is tightly closed; the valves on the vacuum pump group and its pipeline are opened, the pipeline connects the vacuum pump group and the vacuum container, and the gas in the vacuum container is pumped out from the vacuum pump group along the pipeline, so that the internal pressure of the vacuum container is reduced;

[0018] S2: Input a cold source into the low-temperature Dewar, open the valve of the helium supply device and the valve of the pipeline between the helium supply device and the vacuum container, the helium supply device and the vacuum container are connected through the pipeline, the helium in the helium supply device is input into the vacuum container along the pipeline, and the vacuum container is cooled down by using the helium as a heat transfer medium;

[0019] S3: After the liquid nitrogen in the cryogenic Dewar lowers the temperature of the vacuum container to 4.2K or the liquid helium in the cryogenic Dewar lowers the temperature of the vacuum container to 77K, and the helium in the vacuum container is pumped out from the vacuum pump group, the vacuum pump group and the helium supply device adjust the internal pressure of the vacuum container, then the Paschen discharge experiment can be carried out.

[0020] It can be seen from the above technical solutions that the present invention has the following beneficial effects:

[0021] The present invention adopts a valve to open or close a pipeline, adopts a vacuum pump group to pump out the gas of a vacuum container, evacuates the vacuum container, and at the same time, a helium supply device adjusts the pressure of the helium output through a valve to control the pressure in the vacuum container, and makes the helium act as a medium in the vacuum container, so as to increase the cooling rate of the vacuum container in a low-temperature Dewar, and when the temperature of the vacuum container reaches the experimental requirements, the vacuum pump group is adopted to adjust the pressure of the vacuum container, so as to ensure that the temperature zone and pressure of the vacuum container meet the low-temperature Paschen discharge experiment. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural schematic diagram of the present invention;

[0023] Figure 2 This is a curve diagram of the temperature reduction of the vacuum container of the present invention.

[0024] In the figure: 1. Temperature monitor; 2. Vacuum gauge; 3. Vacuum valve one; 4. Vacuum container; 5. Thermometer; 6. Low temperature Dewar; 7. Vacuum valve two; 8. Pressure gauge; 9. Pressure dividing valve; 10. Vacuum valve three; 11. Vacuum valve four; 12. Helium supply device; 13. Vacuum pump group. DETAILED DESCRIPTION

[0025] A preferred embodiment of the present invention is described in detail below with reference to the accompanying drawings.

[0026] like Figure 1 As shown, an experimental device for extremely low temperature Paschen discharge comprises a vacuum container 4 and a cryogenic dewar 6 for accommodating the vacuum container 4, wherein the cryogenic dewar 6 can accommodate a cold source located outside the vacuum container 4, and the vacuum container 4 is connected to a vacuum pump group 13 and a helium supply device 12 outside the cryogenic dewar 6 through pipelines, respectively, and valves are arranged on the pipelines, wherein a cold source is added into the cryogenic dewar 6, and the cold source is outside the vacuum container 4, and cools the vacuum container 4 to reach the temperature required for the experiment; the vacuum container 4 is connected to the helium supply device 12 and the vacuum pump group 13, and two pipelines can be used to communicate with the helium supply device 12 and the vacuum pump group 13 respectively, the helium supply device 12 provides helium to the vacuum container 4, and the vacuum pump group 13 is used to evacuate the vacuum container 4 to reach the pressure required for the experiment.

[0027] As an implementation method in this embodiment, specifically, since the vacuum container 4 is in a vacuum state, in order to reduce the temperature in the vacuum container 4 to the target temperature required by the experiment, the valve of the pipeline between the helium supply device 12 and the vacuum container 4 is opened, so that the helium in the helium supply device 12 is injected into the vacuum container 4, so that the helium in the vacuum container 4 acts as a medium to improve the effect of heat conduction and accelerate the cooling rate of the vacuum container 4; when the temperature in the vacuum container 4 reaches the required target temperature, the valve between the helium supply device 12 and the vacuum container 4 is closed, the valve between the vacuum pump group 13 and the vacuum container 4 is opened, and the vacuum pump group 13 is started, and the vacuum pump group 13 evacuates the vacuum container 4 to reduce the pressure of the vacuum container 4, so as to achieve the Paschen discharge experiment with a lower pressure in the extremely low temperature environment required by the experiment, and the helium supply device 12 can use a compressed gas bottle or a Dewar flask.

[0028] As an implementation method in this embodiment, the vacuum container 4 is connected to a temperature monitor 1 and a vacuum gauge 2 located outside the low-temperature Dewar 6, and the pipeline connecting the vacuum gauge 2 and the vacuum container 4 is provided with a vacuum valve 3, wherein the temperature monitor 1 is used to observe the temperature inside the vacuum container 4, and after the vacuum valve 3 is opened, the pressure inside the vacuum container 4 can be observed in real time through the vacuum gauge 2.

[0029] like Figure 1 As shown, as an implementation method in this embodiment, in order to improve the experimental effect, different from the above, the pipeline includes a main pipeline and two branch pipelines connected to the main pipeline, the end of the main pipeline is connected to the vacuum container 4, the ends of the two branch pipelines are respectively connected to the helium supply device 12 and the vacuum pump group 13, and are respectively provided with a vacuum valve four 11 and a vacuum valve three 10, a vacuum valve two 7 is arranged on the main pipeline, and a pressure gauge 8 and a pressure dividing valve 9 are arranged on the branch pipeline connected to the helium supply device 12, wherein the vacuum valve two 7 is used to connect or disconnect the main pipeline and the branch pipeline, the vacuum valve three 10 is used to connect or disconnect the vacuum pump group 13 in the branch pipeline, the vacuum valve four 11 is used to connect or disconnect the helium supply device 12 in the branch pipeline, the pressure gauge 8 is used to observe the pressure value output by the helium supply device 12, and the pressure dividing valve 9 can fine-tune the helium gas output by the helium supply device 12 toward the vacuum container 4.

[0030] like Figure 1 As shown, a cooling method for an experimental device for extremely low temperature Paschen discharge comprises the following steps:

[0031] S1: In the initial state, the valve is tightly closed; the vacuum pump group 13 and the valve on its pipeline are opened, the pipeline connects the vacuum pump group 13 and the vacuum container 4, and the gas in the vacuum container 4 is pumped out from the vacuum pump group 13 along the pipeline, so that the internal pressure of the vacuum container 4 is reduced;

[0032] S2: Wait until the pressure in the vacuum container 4 is less than 10 -3pa, liquid nitrogen is input into the low-temperature Dewar 6, the helium supply device 12 and the valve of the pipeline between the helium supply device 12 and the vacuum container 4 are opened, the helium supply device 12 is connected with the vacuum container 4 through the pipeline, the helium in the helium supply device 12 is input into the vacuum container 4 along the pipeline, and the vacuum container 4 is cooled down by using the helium as the heat transfer medium. During the cooling process, the vacuum valve 3 10 does not need to be closed;

[0033] S3: After the liquid nitrogen in the low-temperature Dewar 6 reduces the temperature of the vacuum container 4 to 4.2K and the helium in the vacuum container 4 is pumped out from the vacuum pump group 13, the internal pressure of the vacuum container 4 is adjusted by the vacuum pump group 13 and the helium supply device 12, and the Paschen discharge experiment can be carried out.

[0034] The temperature required for the experiment is achieved through a cold source, namely a low-temperature environment of liquid nitrogen (77K) or liquid helium (4.2K).

[0035] According to the above steps and experimental device, the specific operation method is as follows:

[0036] Initially, all valves are tightly closed. Start the vacuum pump group 13, wait for it to run stably, then open the vacuum valve three 10, wait for it to run stably, then open the vacuum valve two 7, connect the vacuum pump group 13 and the vacuum container 4 through the pipeline, so that the pressure inside the vacuum container 4 is reduced, open the vacuum valve one 3, observe the pressure inside the vacuum container 4 through the vacuum gauge 2, and observe the temperature of the thermometer 5 inside the vacuum container 4 through the temperature monitor 1.

[0037] It is necessary to observe that the vacuum gauge 2 gradually stabilizes, that is, the pressure in the vacuum container 4 is less than 10 -3 pa, at this time, liquid nitrogen is input to the outside of the vacuum container 4, that is, the inside of the low-temperature Dewar 6, and the vacuum valve 14 11 and the pressure-dividing valve 9 are opened at the same time. The pressure gauge 8 is observed, the pressure-dividing valve 9 is adjusted, the helium pressure input size is controlled, and the temperature monitor 1 is observed to monitor the cooling situation inside the vacuum container 4. When the temperature drops to the target temperature, that is, the low-temperature environment of liquid nitrogen (77K), the pressure-dividing valve 9 is controlled, the vacuum gauge 2 is observed, and the helium in the vacuum container 4 is pumped out from the vacuum pump group 13, and the vacuum pump group 13 and the helium supply device 12 are adjusted again to make the pressure inside the vacuum container 4 reach the required condition, that is, the pressure inside the vacuum container 4 is at 10 -3 ~10 3 pa, Paschen discharge experiment can be carried out.

[0038] As an implementation method in this embodiment, if it is necessary to remove the liquid nitrogen inside the cryogenic Dewar 6 and input liquid helium, that is, in order to provide a lower experimental environment temperature, the pressure dividing valve 9 is adjusted synchronously, the pressure gauge 8 and the temperature monitor 1 are observed, and the cooling rate inside the vacuum container 4 is controlled. When the temperature is reduced to the target temperature, that is, the low temperature environment of liquid helium (4.2K), the pressure dividing valve 9 is controlled, the vacuum gauge 2 is observed, and the helium in the vacuum container 4 is pumped out from the vacuum pump group 13, and the pressure inside the vacuum container 4 is adjusted to the required condition, that is, the pressure inside the vacuum container 4 is at 10 -3 ~10 3 pa, the Paschen discharge experiment can be carried out.

[0039] A stage is installed in the vacuum container 4. The stage is not in contact with the inner wall of the vacuum container 4. The test sample can also be placed on the stage. Two thermometers 5 are installed on the stage. The measured temperatures are recorded as T1 and T2. The purpose of placing the two thermometers 5 is to consider detection errors or damage, and on the other hand, to consider the uniformity of temperature. The specific temperature curves of T1 and T2 are as follows: Figure 2 shown.

[0040] For the sudden drop in temperature in the curve, the increase in the slope of this point means that liquid nitrogen is replenished again, that is, the liquid nitrogen outside the vacuum container 4 evaporates and the liquid level is low. We need to continue to input liquid nitrogen to provide a cold source environment. According to the curve, the existing vacuum container 4 is cooled and directly placed in liquid nitrogen until it meets the Paschen discharge experiment. Its temperature is not easy to control and is very easy to deviate from the temperature required by the experiment.

[0041] When used in this application, the pressure dividing valve 9 is adjusted to a larger value, the rate of helium flowing into the vacuum container 4 is increased, and the rate of helium flowing into the vacuum container 4 is greater than the suction force of the vacuum pump group 13 on the vacuum container 4. As time goes by, the pressure in the vacuum container 4 becomes greater, and the heat conduction of the low-temperature environment inside and outside the vacuum container 4 increases, and the cooling rate will increase appropriately; if the vacuum container 4 reaches the temperature required for the experiment, that is, 4.2K, the pressure dividing valve 9 is adjusted to a smaller value, so that the suction force of the vacuum container 4 is greater than the helium flowing into the pressure dividing valve 9, and the pressure in the vacuum container 4 is reduced, thereby reducing the heat conduction effect, and the temperature of the vacuum container 4 can be effectively controlled. The table below shows the data recorded for T1 and T2 over time.

[0042]

[0043]

[0044] The above-described embodiments are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. An experimental device for extremely low temperature Paschen discharge, comprising a vacuum container (4), characterized in that: It also includes a low-temperature dewar (6) for accommodating the vacuum container (4); the vacuum container (4) is connected to a vacuum pump group (13) and a helium supply device (12) outside the low-temperature dewar (6) through pipelines, respectively; and valves are arranged on the pipelines; the low-temperature dewar (6) is capable of accommodating a cold source located outside the vacuum container (4).

2. The experimental device for extremely low temperature Paschen discharge according to claim 1, characterized in that: The pipeline comprises a main pipeline and two branch pipelines connected to the main pipeline, the end of the main pipeline is in communication with the vacuum container (4), the ends of the two branch pipelines are respectively in communication with the helium supply device (12) and the vacuum pump group (13), and are respectively provided with a vacuum valve four (11) and a vacuum valve three (10).

3. The experimental device for extremely low temperature Paschen discharge according to claim 2, characterized in that: The main pipe is provided with a second vacuum valve (7).

4. The experimental device for extremely low temperature Paschen discharge according to claim 1, characterized in that: A pressure gauge (8) and a pressure dividing valve (9) are provided on the branch pipeline connected to the helium supply device (12).

5. The experimental device for extremely low temperature Paschen discharge according to claim 1, characterized in that: The vacuum container (4) is connected to a temperature monitor (1) and a vacuum gauge (2) located outside the low-temperature Dewar (6).

6. The experimental device for extremely low temperature Paschen discharge according to claim 1, characterized in that: The cold source includes liquid nitrogen or liquid helium.

7. The experimental device for extremely low temperature Paschen discharge according to claim 5, characterized in that: A vacuum valve (3) is provided on the pipeline connecting the vacuum gauge (2) and the vacuum container (4).

8. The cooling method for the experimental device for extremely low temperature Paschen discharge according to any one of claims 1 to 7, characterized in that: The steps include: S1: In the initial state, the valve is tightly closed; the vacuum pump group (13) and the valve on the pipeline are opened, the pipeline connects the vacuum pump group (13) and the vacuum container (4), and the gas in the vacuum container (4) is pumped out from the vacuum pump group (13) along the pipeline, so that the internal pressure of the vacuum container (4) is reduced; S2: Wait until the pressure in the vacuum container 4 is less than 10 -3 pa, liquid nitrogen or liquid helium is introduced into the low-temperature Dewar (6), the valve of the helium supply device (12) and the pipeline between the helium supply device (12) and the vacuum container (4) is opened, the helium supply device (12) and the vacuum container (4) are connected through the pipeline, the helium in the helium supply device (12) is introduced into the vacuum container (4) along the pipeline, and the vacuum container (4) is cooled by using the helium as a heat transfer medium; S3: After the liquid nitrogen in the cryogenic Dewar (6) lowers the temperature of the vacuum container (4) to 4.2K or the liquid helium in the cryogenic Dewar (6) lowers the temperature of the vacuum container (4) to 77K, and the helium in the vacuum container (4) is pumped out from the vacuum pump group (13), the vacuum pump group (13) and the helium supply device (12) adjust the internal pressure of the vacuum container (4), then the Paschen discharge experiment can be carried out.

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