Electrical tree in-situ growth observation device based on low-temperature objective lens

Abstract

The utility model relates to the technical field of insulating material electrical tree growth observation devices, and provides an electrical tree in-situ growth observation device based on a low-temperature objective lens, which comprises a low-temperature thermostat used for providing a low-temperature constant-temperature environment; the high-voltage discharge sample cavity is communicated with the low-temperature thermostat, a sample is arranged in the high-voltage discharge sample cavity, and the high-voltage discharge sample cavity is connected with a high-voltage electrode and a ground electrode; the low-temperature objective lens in-situ observation assembly is communicated with the high-voltage discharge sample cavity, and the low-temperature objective lens in-situ observation assembly is used for observing the electrical tree in-situ growth process of the sample. The electrical tree in-situ growth observation device based on the low-temperature objective lens provided by the utility model can provide an electrical tree growth platform with a wide temperature range of 40K-300K, so that fine in-situ observation of an electrical tree dendronization process is realized; the low-temperature thermostat adopts a helium exchange heat exchange scheme to realize thermal mechanical isolation, so that the use of low-temperature liquid is reduced, the service life of the device is prolonged, and the cost is reduced.

Description

Technical Field

[0001] This utility model relates to the technical field of electrical tree growth observation devices for insulating materials, and in particular to an in-situ electrical tree growth observation device based on a low-temperature objective lens. Background Technology

[0002] The commonly used insulating material for superconducting magnets is impregnated epoxy resin. During operation, the epoxy resin must withstand extreme conditions such as low temperatures (<120K), vacuum (<0.1Pa), and strong electromagnetic fields (>5T), severely testing its withstand voltage. The electrical tree growth characteristics of epoxy resin at low temperatures represent a long-term aging process. Detailed research into the growth patterns of electrical trees, including initiation voltage and tree shape, can provide valuable reference for engineering applications. The growth pattern of electrical trees is mainly reflected in the fractal characteristics of its growth process.

[0003] In the existing technology, most studies on electrical tree testing of insulating materials are concentrated at room temperature, while studies at low temperatures lack sophisticated in-situ observation devices. Sophisticated in-situ observation requires close proximity to the sample surface, but the existence of a vacuum chamber limits this requirement. Utility Model Content

[0004] This invention provides an in-situ observation device for electrical treeing based on a low-temperature objective lens, which solves the problem that existing technologies require close contact with the sample surface for precise in-situ observation, and enables precise in-situ observation of the electrical treeing process in insulating materials.

[0005] This invention provides an in-situ observation device for electrical tree growth based on a low-temperature objective lens, comprising:

[0006] Low-temperature thermostats are used to provide a low-temperature, constant-temperature environment.

[0007] A high-voltage discharge sample chamber is connected to the low-temperature thermostat. The high-voltage discharge sample chamber contains a sample and is connected to a high-voltage electrode and a ground electrode.

[0008] The low-temperature objective in-situ observation component is connected to the high-voltage discharge sample chamber, and the low-temperature objective in-situ observation component is used to observe the in-situ growth process of electrical treeing in the sample.

[0009] According to the present invention, an in-situ observation device for electrical tree growth based on a low-temperature objective lens is provided, wherein the low-temperature thermostat includes:

[0010] The GM refrigeration unit is mounted on a bracket.

[0011] A first vacuum chamber is provided for the GM refrigerator to pass through, and the first vacuum chamber provides a vacuum environment for the GM refrigerator.

[0012] A primary cooling screen is installed inside the first vacuum chamber, and the primary cooling screen transfers cooling energy through a primary cooling head;

[0013] A cold head heat exchanger is located at the end of the GM refrigerator;

[0014] A secondary helium heat exchange chamber is disposed inside the first vacuum chamber, and the interior of the secondary helium heat exchange chamber contains helium. The cooling capacity of the GM refrigerator is transferred to the helium through the cold head heat exchanger.

[0015] A cooling platform is located at the bottom of the secondary helium heat exchange chamber;

[0016] A cold finger penetrates the first vacuum chamber, with the other end of the cold finger extending into the high-voltage discharge sample chamber; and the sample is carried at one end of the cold finger located in the high-voltage discharge sample chamber.

[0017] According to the present invention, an in-situ observation device for electric tree growth based on a low-temperature objective lens is provided, wherein the GM refrigerator and the first vacuum hood are connected by a welded corrugated pipe.

[0018] According to the present invention, an in-situ observation device for electric tree growth based on a low-temperature objective lens is provided, which further includes an installation platform, on which the support, the first vacuum hood and the high-voltage discharge sample chamber are provided; and an air-floating shock absorber is provided between the support and the installation platform.

[0019] According to the present invention, an in-situ observation device for electric tree growth based on a low-temperature objective lens is provided, wherein the high-voltage discharge sample chamber includes:

[0020] A ceramic high-voltage sleeve is connected to the high-voltage electrode and the ground electrode via a KF25 interface; the ceramic high-voltage sleeve is used to isolate vacuum.

[0021] The second vacuum chamber has the cold finger extending into it; and the second vacuum chamber is connected to the first vacuum chamber via a KF40 interface, thus conducting the vacuum between them.

[0022] The objective lens cavity is connected to the top of the second vacuum chamber;

[0023] A transition cavity is disposed at the top of the objective cavity, and the transition cavity is used to connect the in-situ observation assembly of the cryogenic objective.

[0024] According to the in-situ observation device for electric tree growth based on a low-temperature objective lens provided by this utility model, the high-voltage discharge sample chamber further includes:

[0025] A visualization quartz window is tilted and positioned on the side of the objective lens cavity.

[0026] According to the present invention, an in-situ observation device for electrical tree growth based on a cryogenic objective lens is provided, wherein the cryogenic objective lens in-situ observation component includes:

[0027] Three-dimensional displacement slide with built-in reduction screw;

[0028] A camera, used for taking pictures;

[0029] An objective lens barrel is disposed at the bottom of the camera, and the top of the objective lens barrel is sealed with quartz glass; and the objective lens barrel is disposed on the three-dimensional displacement slide.

[0030] A connecting tube, one end of which is connected to the objective lens tube;

[0031] An objective lens is connected to the end of the connecting tube opposite to the objective lens tube; and the connecting tube extends into the transition cavity.

[0032] According to the present invention, an in-situ observation device for electric tree growth based on a low-temperature objective lens is provided, wherein the connecting tube is a flexible corrugated tube.

[0033] According to the present invention, an in-situ observation device for electric tree growth based on a low-temperature objective lens is provided. The in-situ observation component of the low-temperature objective lens further includes a beam splitter, which is disposed on the objective lens tube and is used to provide visible light intensity.

[0034] According to the present invention, an in-situ observation device for electric tree growth based on a low-temperature objective lens is provided, wherein the first vacuum hood is made of 304 stainless steel and the interlayer is made of high-vacuum multilayer heat insulation material.

[0035] This invention provides an in-situ observation device for electric tree growth based on a cryogenic objective. A cryogenic thermostat provides a cryogenic constant temperature environment. A high-voltage discharge sample chamber is connected to the cryogenic thermostat and contains a sample. The cryogenic objective in-situ observation component is connected to the high-voltage discharge sample chamber. The cryogenic objective can observe the in-situ electric tree growth process of the sample, providing an electric tree growth platform with a wide temperature range of 40K-300K, and realizing fine in-situ observation of the electric treeing process.

[0036] The cryogenic thermostat uses a helium exchange heat exchange scheme to achieve thermomechanical isolation, reducing the use of cryogenic liquids, thereby increasing the service life of the device and reducing costs.

[0037] In addition, the temperature is strictly controlled by a low-temperature thermostat, and the high-voltage discharge sample chamber is strictly controlled by high voltage, which can prevent the occurrence of Pascal discharge between high and low voltage. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0039] Figure 1 This is a schematic diagram of the structure of the in-situ growth observation device for electric tree branches based on a low-temperature objective lens provided by this utility model.

[0040] Figure 2 This is a top view of the in-situ growth observation device for electric tree branches based on a low-temperature objective lens provided by this utility model.

[0041] Figure 3 yes Figure 2 Sectional view of AA.

[0042] Figure label:

[0043] 1. Cryostat; 2. High-voltage discharge sample chamber; 3. Cryostat objective lens in-situ observation assembly; 4. Mounting platform; 5. Air flotation shock absorber; 11. GM refrigerator; 12. Support; 13. Cold finger; 14. First vacuum chamber; 15. First-stage cold shield; 16. First-stage cold head; 17. Cold head heat exchanger; 18. Second-stage helium heat exchange chamber; 19. Cold-conducting stage; 21. Second vacuum chamber; 22. Objective lens chamber; 23. Transition chamber; 24. Visualization quartz window; 31. Three-dimensional displacement stage; 32. Camera; 33. Objective lens tube; 34. Connecting tube; 35. Objective lens; 36. Beam splitter. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of this utility model clearer, the technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0045] In the description of the embodiments of this utility model, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this utility model. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0046] The following is combined Figures 1-3 This invention describes an in-situ observation device for electric tree growth based on a low-temperature objective lens.

[0047] like Figure 1 As shown in the figure, the in-situ growth observation device for electric tree based on a low-temperature objective lens provided in this embodiment of the present invention includes a low-temperature thermostat 1, a high-voltage discharge sample chamber 2, and a low-temperature objective lens in-situ observation component 3.

[0048] The cryostat 1 provides a constant-temperature environment, precisely controlling the required low-temperature conditions for the experiment. The high-voltage discharge sample chamber 2 is connected to the cryostat 1, housing the sample and connecting the high-voltage electrode to the ground electrode. The high-voltage discharge sample chamber 2 provides a high-voltage environment for the sample, simulating high-voltage discharge conditions in a real electric field. The cryogenic objective in-situ observation assembly 3 is connected to the high-voltage discharge sample chamber 2 and is used to observe the in-situ growth process of electrical trees on the sample. The cryogenic objective in-situ observation assembly 3 allows direct observation of the electrical tree growth process without damaging the sample.

[0049] The in-situ observation device for electric tree growth of the low-temperature objective lens provided by this utility model provides a low-temperature constant temperature environment through a low-temperature thermostat, and a high-voltage discharge sample chamber simulates a high-voltage environment for the sample. The low-temperature objective lens can observe the in-situ growth process of electric tree in the sample, so as to provide an electric tree growth platform with a wide temperature range of 40K-300K, and realize fine in-situ observation of the electric treeing process.

[0050] like Figure 2 and Figure 3 As shown, in a feasible embodiment of this utility model, the low-temperature thermostat 1 includes a GM refrigerator 11, a first vacuum hood 14, a first-stage cold shield 15, a first-stage cold head 16, a cold head heat exchanger 17, a second-stage helium heat exchange chamber 18, a cold-conducting stage 19, and a cold finger 13.

[0051] The GM cryostat 11 is mounted on the support 12. The GM cryostat completely overcomes the problem of cryogenic liquid consumption, allowing the device to operate continuously at the set temperature for tens of hours. However, the use of the GM cryostat 11 also introduces vibration issues. The vibration of the GM cryostat 11 is approximately 25 μm. To overcome this problem, helium gas exchange is used to isolate the cold head from the test components.

[0052] Specifically, the first vacuum chamber 14 is penetrated by the GM refrigerator 11, providing a vacuum environment for the GM refrigerator 11, reducing the potential influence of external air molecules on the experimental process, and improving the accuracy and reliability of the experiment. A primary cold shield 15 is located inside the first vacuum chamber 14, and the primary cold shield transfers cooling energy through a primary cold head 16. A cold head heat exchanger 17 is located at the end of the GM refrigerator 11; a secondary helium heat exchange chamber 18 is located inside the first vacuum chamber 14, and the interior of the secondary helium heat exchange chamber 18 contains helium, with the cooling energy of the GM refrigerator 11 transferred to the helium through the cold head heat exchanger 17. A cooling stage 19 is located at the bottom of the secondary helium heat exchange chamber 18; a cold finger 13 penetrates the first vacuum chamber 14, with the other end of the cold finger 13 extending to the high-voltage discharge sample chamber 2; and the cold finger 13 at one end of the high-voltage discharge sample chamber 2 carries the sample.

[0053] The first vacuum chamber 14 is made of 304 stainless steel, and the interlayer is made of high-vacuum multilayer heat insulation material.

[0054] The working process is as follows: The cooling capacity of the GM refrigerator 11 is transferred to helium by the cold head heat exchanger 17, and the helium then transfers its cooling capacity to the cooling platform 19. After being heated on the cooling platform 19, the helium's temperature rises and its density decreases. It then floats up, absorbs heat from the cold head heat exchanger 17, its temperature decreases, its density increases, and it sinks again. This repeated process achieves helium heat exchange while simultaneously achieving complete vibration isolation between the primary cold head 16 of the refrigerator and the cooling platform 19. Sample cooling relies on the cooling platform 19 and the cold finger 13, with the sample stage mounted on the cold finger 13. The cold finger 13 is an oxygen-free copper rod with a diameter of 10mm and a length of 250mm, possessing highly efficient heat transfer capabilities. The primary cold shield 15 transfers cooling capacity from the primary cold head 16 of the refrigerator via the upper flange, achieving radiative heat leakage control of the entire secondary helium heat exchange chamber 18.

[0055] To further reduce vibration, in one feasible embodiment of this invention, the GM refrigerator 11 and the first vacuum chamber 14 are connected by a welded bellows, which can control the vibration at the nanometer level.

[0056] In one feasible embodiment of this utility model, it further includes an installation platform 4, on which a support 12, a first vacuum chamber 14, and a high-voltage discharge sample chamber 2 are mounted; the installation platform 4 serves as the stable foundation of the entire system. Furthermore, an air-float vibration damper 5 is installed between the support 12 and the installation platform 4. Utilizing the vibration damping and isolation characteristics of air-float technology, it effectively reduces mechanical vibration interference that may occur during the experiment, further improving the accuracy and stability of the experiment, and providing strong support for long-term, continuous experimental observation.

[0057] The above embodiments, by introducing installation platform 4, not only optimize the layout and structure of the entire observation system, but also significantly improve the accuracy and stability of the experiment.

[0058] In one feasible embodiment of this invention, the high-voltage discharge sample chamber 2 includes a ceramic high-voltage sleeve, a second vacuum chamber 21, an objective lens chamber 22, and a transition chamber 23. The ceramic high-voltage sleeve is connected to the high-voltage electrode and the ground electrode via a KF25 interface. The ceramic high-voltage sleeve ensures the stable distribution of the high-voltage electric field within the sample chamber. In addition, the ceramic material has excellent insulation properties and resistance to high temperature and high pressure, which can effectively isolate the vacuum environment, prevent electric field leakage, and ensure the safety and accuracy of the experiment.

[0059] The cold finger 13 extends into the second vacuum chamber 21, facilitating more precise temperature control of the sample. The second vacuum chamber 21 is connected to the first vacuum chamber 14 via a KF40 interface, establishing a vacuum between them. The objective cavity 22 connects to the top of the second vacuum chamber 21, providing a convenient channel for optical observation. Researchers can observe the sample in situ through the objective lens, acquiring images and data in real time during the experiment. The transition cavity 23 is located at the top of the objective cavity 22 and is used to connect the cryogenic objective in-situ observation assembly 3. The transition cavity 23 serves as a connection and transition, allowing the cryogenic objective lens to be smoothly installed and observed from the sample within the sample chamber.

[0060] In the above embodiments, the structural design of the high-voltage discharge sample chamber 2 brings multiple beneficial effects, such as high-voltage isolation and stability, vacuum environment maintenance, convenient optical observation, structural compactness, and connection and transition functions, which improves the accuracy and reliability of the experiment and provides strong support for research in fields such as in-situ production and observation of electric tree trees.

[0061] In one feasible embodiment of this utility model, the high-voltage discharge sample chamber 2 further includes a visualization quartz window 24, which is tilted on the side of the objective lens chamber 22 to facilitate experimental observation and adjustment of the low-temperature objective lens.

[0062] In one feasible embodiment of this invention, the cryogenic objective in-situ observation assembly 3 includes a three-dimensional displacement slide 31, a camera 32, an objective tube 33, a connecting tube 34, and an objective lens 35. The three-dimensional displacement slide 31 has a built-in reduction screw, which allows the displacement to be controlled at the nanometer level. The camera 32 is used for taking pictures and has high-resolution imaging capabilities, enabling it to capture subtle changes in the growth of electrical trees. The top of the objective tube 33 is sealed with quartz glass; and the objective tube 33 is mounted on the three-dimensional displacement slide 31; one end of the connecting tube 34 is connected to the objective tube 33; the objective lens 35 is connected to the end of the connecting tube 34 facing away from the objective tube 33; and the connecting tube 34 extends into the transition cavity 23.

[0063] Specifically, the camera is a CCD camera. In the above embodiment, the focusing method is as follows: First, coarse adjustment. The three-dimensional displacement slide 31 connected by the bellows achieves coarse adjustment for observation by the objective lens 35. By manually adjusting the knob of the three-dimensional displacement slide 31, the coarse adjustment is completed after the CCD camera displays the outline of the object; second, fine adjustment. After the outline of the object appears, the three-dimensional displacement slide 31 is slowly adjusted by the program until the object is clear, and the fine adjustment is completed. The entire focusing of the objective lens 35 is achieved through the flexible connection of the bellows. The low-temperature objective lens is cooled by a copper cooling belt connected to a secondary cold screen, thereby achieving in-situ observation at low temperatures and overcoming the problem of optical path radiation noise at room temperature. The objective lens barrel 33, made of 304 stainless steel, is responsible for connecting the objective lens 35, and its upper part is sealed with quartz glass. The bottom of the objective lens barrel 33 and the transition cavity 23 are connected by a flexible bellows, which allows the objective lens 35 to move with the three-dimensional displacement slide 31. The top features a CCD camera and beam splitter 36, responsible for capturing images of electrical tree aging and providing visible light intensity.

[0064] Beam splitter 36 is mounted on objective lens tube 33 and is used to provide visible light intensity.

[0065] The working process of the in-situ observation device for electric tree growth using a low-temperature objective lens provided by this utility model is as follows: When conducting an electric tree aging observation experiment, the system is first evacuated, the circuit is fully connected, and then an appropriate amount of helium is introduced into the secondary helium heat exchange chamber 18. After that, the GM refrigerator 11 is turned on to cool down and the temperature controller is turned on until the target temperature stabilizes. Finally, the light source of the beam splitter 36 and the CCD camera are turned on to capture the electric tree growth image at low temperature in real time. The growth of electric trees in insulating materials can be observed in the low-temperature range of 77K or lower. The in-situ observation component 3 of the low-temperature objective lens can provide in-situ observation of electric tree growth at low temperature. The low vibration of the low-temperature thermostat 1 can reduce the observation error of the objective lens 35. The cold head-sample isolation is achieved by exchanging helium for heat exchange, which can control the vibration at the nanometer level.

[0066] In summary, the low-temperature objective lens provided by this invention is used for in-situ observation of electric tree growth. The GM refrigerator enables continuous dry cooling without liquid helium, and the experimental device is installed in a low-temperature thermostat that is damped by a bellows and an air-float damper. A temperature controller is used to achieve low-temperature conditions with high precision temperature control over a wide temperature range. A helium exchange heat exchange scheme is adopted to achieve thermomechanical isolation. The key point is to overcome the technical difficulties of close-fitting observation by assembling and using the low-temperature objective lens, thus forming a complete in-situ observation system for the growth process of electric trees on insulating materials that integrates high voltage, low temperature, and vacuum.

[0067] In the description of the embodiments of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this utility model according to the specific circumstances.

[0068] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "method," "specific method," or "some methods," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or method is included in at least one embodiment or method of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or method. Furthermore, the specific features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments or methods. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or methods described in this specification, as well as the features of different embodiments or methods.

[0069] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model.

Claims

1. A device for in-situ observation of electrical tree growth based on a low-temperature objective lens, characterized in that, include: Low-temperature thermostat (1) is used to provide a low-temperature constant temperature environment; The high-voltage discharge sample chamber (2) is connected to the low-temperature thermostat (1). The high-voltage discharge sample chamber (2) contains a sample and is connected to the high-voltage electrode and the ground electrode. The low-temperature objective lens in-situ observation component (3) is connected to the high-voltage discharge sample chamber (2), and the low-temperature objective lens in-situ observation component (3) is used to observe the in-situ growth process of electrical treeing in the sample.

2. The in-situ observation device for electrical tree growth based on a low-temperature objective lens according to claim 1, characterized in that, The cryostat (1) includes: The GM refrigeration unit (11) is mounted on the bracket (12); A first vacuum hood (14) is provided for the GM refrigerator (11) to pass through, and the first vacuum hood (14) provides a vacuum environment for the GM refrigerator (11); A primary cold shield (15) is disposed inside the first vacuum chamber (14), and the primary cold shield transfers cooling energy through a primary cold head (16); A cold head heat exchanger (17) is disposed at the end of the GM refrigerator (11); A secondary helium heat exchange chamber (18) is disposed inside the first vacuum shroud (14), and the interior of the secondary helium heat exchange chamber (18) contains helium. The cooling capacity of the GM refrigerator (11) is transferred to the helium through the cold head heat exchanger (17). A cooling platform (19) is located at the bottom of the secondary helium heat exchange chamber (18); A cold finger (13) penetrates the first vacuum shroud (14), and the other end of the cold finger (13) extends to the high-voltage discharge sample chamber (2); and the cold finger (13) carries the sample at one end of the high-voltage discharge sample chamber (2).

3. The in-situ observation device for electric tree growth based on a low-temperature objective lens according to claim 2, characterized in that, The GM refrigerator (11) and the first vacuum hood (14) are connected by a welded bellows.

4. The in-situ growth observation device for electric tree branches based on a low-temperature objective lens according to claim 2, characterized in that, It also includes an installation platform (4), on which the bracket (12), the first vacuum hood (14) and the high-voltage discharge sample chamber (2) are provided; and an air flotation shock absorber (5) is provided between the bracket (12) and the installation platform (4).

5. The in-situ growth observation device for electrical treeing based on a low-temperature objective lens according to claim 2, characterized in that, The high-voltage discharge sample chamber (2) includes: A ceramic high-voltage sleeve is connected to the high-voltage electrode and the ground electrode via a KF24 interface; the ceramic high-voltage sleeve is used to isolate vacuum. The second vacuum chamber (21) has the cold finger (13) extending into it; and the second vacuum chamber (21) and the first vacuum chamber (14) are connected via a KF40 interface to conduct the vacuum between them; The objective lens cavity (22) is connected to the top of the second vacuum chamber (21); The transition cavity (23) is located at the top of the objective cavity (22) and is used to connect the cryogenic objective in-situ observation assembly (3).

6. The in-situ observation device for electric tree growth based on a low-temperature objective lens according to claim 5, characterized in that, The high-voltage discharge sample chamber (2) further includes: A visualization quartz window (24) is tilted and positioned on the side of the objective lens cavity (22).

7. The in-situ observation device for electric tree growth based on a low-temperature objective lens according to claim 5, characterized in that, The in-situ observation assembly (3) for the cryogenic objective lens includes: Three-dimensional displacement slide (31), with built-in reduction screw; Camera (32), used for taking pictures; An objective lens tube (33) is disposed at the bottom of the camera (32), and the top of the objective lens tube (33) is sealed with quartz glass; and the objective lens tube (33) is disposed on the three-dimensional displacement slide (31); A connecting tube (34) is connected at one end to the objective lens tube (33); The objective lens (35) is connected to the end of the connecting tube (34) facing away from the objective lens tube (33); and the connecting tube (34) extends into the transition cavity (23).

8. The in-situ observation device for electric tree growth based on a low-temperature objective lens according to claim 7, characterized in that, The connecting pipe (34) is a flexible corrugated pipe.

9. The in-situ observation device for electric tree growth based on a low-temperature objective lens according to claim 7, characterized in that, The cryogenic objective in-situ observation assembly (3) also includes a beam splitter (36), which is disposed on the objective tube (33) and is used to provide visible light intensity.

10. The in-situ observation device for electrical tree growth based on a low-temperature objective lens according to claim 2, characterized in that, The first vacuum shroud (14) is made of 304 stainless steel, and the interlayer is a high-vacuum multilayer heat insulation material.

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