Device and method for measuring contact thermal resistance under vacuum condition by taking electron beam as heat source

Abstract

The invention discloses a method and a device for measuring contact thermal resistance under a vacuum condition by taking an electron beam as a heat source, and relates to the technical field of thermotechnical measurement. The device comprises a vacuum cavity, an upper pressing plate with a through hole, an electron beam heating unit, a tungsten ingot, a sample piece stacking body formed by coaxially stacking a sample piece A and a sample piece B, a water cooling module, a heat insulation unit, a pressure applying unit, a temperature measuring unit and a control unit. The method comprises the following steps: heating a tungsten ingot by electron beams in vacuum, and establishing a steady-state temperature field through water cooling; acquiring steady-state temperature data under two different heating powers; a group of data is used as a reference, the interface temperature difference and the heat flux density are accurately solved by adopting a reference method in combination with the heat conductivity of the sample, and finally the contact thermal resistance is calculated. According to the method, the problems of air heat conduction interference, insufficient heat source power and large lateral heat loss in a traditional method are solved, and high-precision direct measurement of the contact thermal resistance of the solid interface under the vacuum, high-temperature and high-heat-flow conditions is realized.

Description

Technical Field

[0001] This invention relates to the field of thermal measurement technology, and in particular to a device and method for accurately measuring the contact thermal resistance between the interfaces of two solid materials in a vacuum environment using a high-energy electron beam as a heat source. Background Technology

[0002] In engineering practice, any interface with mechanical contact generates contact thermal resistance. This microscopic "thermal barrier" can cause a sharp increase in localized temperature on a macroscopic scale, posing a serious threat to the reliability and lifespan of high-end equipment such as spacecraft, high-power chips, and lasers. Therefore, accurate measurement of contact thermal resistance has become a key prerequisite for precise thermal design, optimization of heat dissipation systems, selection of thermal interface materials, and evaluation of assembly processes. It is the cornerstone for improving product performance consistency and safety.

[0003] Currently, the most commonly used contact thermal resistance measurement methods in the engineering field are mainly based on steady-state methods using resistance heating. However, these methods are increasingly revealing their inherent limitations when dealing with the extreme operating conditions of modern precision engineering. First, these measurements are typically performed in atmospheric pressure air, creating an additional heat conduction channel in parallel with the solid contact point due to residual air at the interface. This "heat leakage" significantly lowers the measured contact thermal resistance value, resulting in severely distorted data that fails to accurately reflect the actual operating state of the device in a vacuum environment or after it has been filled with thermally conductive materials. Second, the power density of traditional resistance heat sources is limited, making it difficult to reproduce the extreme heat flux of hundreds of watts per square centimeter in high-power devices. This means that interfaces that pass low-load tests in the laboratory may fail rapidly under real-world conditions due to their inability to withstand high thermal stress, failing to provide effective risk warnings for product design. Furthermore, the structural design of traditional measuring devices cannot completely eliminate lateral heat loss and heat exchange with the external environment, and system errors such as lead wire thermal conductivity are often overlooked. All of these factors restrict measurement accuracy and fail to meet the urgent needs of current high-precision R&D and quality inspection.

[0004] It is worth noting that although existing technologies employ electron beams as heat sources for measurement, their purpose and measurement objects differ fundamentally from those of this invention. These methods primarily focus on measuring the thermal conductivity of the material at high temperatures, a thermophysical property. Their core devices typically include a "standard" for calibrating heat flow, inferring the material's thermal conductivity by measuring the heat flow and temperature difference between a single homogeneous sample and the standard. However, they do not characterize the interfacial contact state between two independent solid components, and their measurement principles and structural designs cannot be directly used to solve for the crucial engineering parameter of interfacial contact thermal resistance.

[0005] Therefore, developing a novel method and apparatus that can simulate high heat flux density in a vacuum environment and directly measure the contact thermal resistance of two solid interfaces with high precision has become a technical challenge that urgently needs to be solved in this field. Summary of the Invention

[0006] This invention aims to overcome the shortcomings of existing technologies and solve the problem of how to directly measure the contact thermal resistance between two solid materials at high precision and high temperature in a vacuum environment, especially how to avoid air thermal conduction interference, how to achieve high heat density input, and how to accurately solve the interface temperature difference and heat flow.

[0007] To solve the above problems, the present invention adopts the following technical solution:

[0008] On one hand, the present invention provides a contact thermal resistance measuring device under vacuum conditions using an electron beam as a heat source, comprising:

[0009] The vacuum chamber provides a vacuum environment for the entire measuring device;

[0010] An upper pressure plate is disposed within the vacuum cavity, and the upper pressure plate has a central through hole;

[0011] An electron beam heating unit is used to generate an electron beam, which is incident through the central through-hole;

[0012] A heat-conducting block is disposed below the upper pressure plate and is coaxial with the axis of the incident electron beam;

[0013] The sample stack consists of sample A and sample B, which are coaxially and in close contact from top to bottom. The sample stack is located below the heat-conducting block to form the contact interface to be tested.

[0014] A water-cooling module is located below the sample stack and includes a water-cooling cover plate and its internal cooling channels for cooling the bottom of sample B.

[0015] The thermal insulation unit, which circumferentially encloses the stacked sample body, is used to reduce radial heat loss;

[0016] A pressure application unit is used to apply axial pressure to the sample stack;

[0017] The temperature measuring unit includes a first thermocouple and a second thermocouple disposed at the upper and lower ends of sample A, and a third thermocouple and a fourth thermocouple disposed at the upper and lower ends of sample B.

[0018] The control and data acquisition unit is configured to: control the electron beam heating unit to heat to steady state at two different power levels, acquire the steady-state temperature of each thermocouple, and calculate the contact thermal resistance between the interface of sample A and sample B based on the reference method.

[0019] Preferably, the pressure application unit includes a bolt and a nut, with the two ends of the nut passing through the upper pressure plate and the water-cooled cover plate respectively and threadedly connected to the nut;

[0020] An adjustable pressure of 0 MPa to 20 MPa is applied to the sample stack by adjusting the spacing between the two nuts.

[0021] Multiple pressure application units are evenly distributed around the sample stack.

[0022] Preferably, the heat insulation unit includes an aluminum silicate fiber sleeve and aluminum foil applied to the inner and outer surfaces of the aluminum silicate fiber sleeve.

[0023] Preferably, a zirconium oxide heat insulation pad is provided between the upper pressure plate and the heat-conducting block.

[0024] Preferably, the diameter of the electron beam spot generated by the electron beam heating unit is 3 mm to 8 mm.

[0025] Preferably, the control and data acquisition unit is configured to calculate the axial heat flux density of sample A and sample B respectively, based on the relationship between thermal conductivity and temperature, when performing the reference method calculation. and and in At that time, it is assumed that the one-dimensional heat transfer assumption is satisfied, where The average heat flux density at the interface.

[0026] On the other hand, the present invention also provides a method for measuring contact thermal resistance under vacuum conditions using the above-described device, comprising the following steps:

[0027] S1. In a vacuum environment, the sample stack formed by coaxially stacking sample A and sample B is heated by irradiating the heat-conducting block with an electron beam, and then cooled by a water-cooling module to establish a first steady-state temperature field.

[0028] S2. Obtain the axial temperature data of sample A and sample B under the first steady state through the temperature measurement unit;

[0029] S3. Change the electron beam heating power to establish a second steady-state temperature field and obtain the corresponding second set of axial temperature data;

[0030] S4. Using the first set of steady-state data as a reference, and combining it with the two sets of steady-state temperature data, the reference method is used to solve for the temperature at the interface between sample A and sample B. and and interfacial heat flux density ;

[0031] S5. According to the formula Calculate the contact thermal resistance.

[0032] Preferably, in step S4, the interface temperature is calculated. and At that time, based on the thermal conductivity of sample A and sample B and The dependence on temperature is calculated by integrating the axial heat flux density.

[0033] Preferably, before step S4, a one-dimensional heat transfer assumption verification step is included: calculating the axial heat flux density of sample A. Axial heat flux density of sample B If the relative deviation exceeds the preset threshold, the measurement is deemed invalid.

[0034] The preset threshold is 2% to 10%.

[0035] Compared to existing technologies, this invention constructs a "sample A-sample B" stacked structure specifically for directly measuring interfacial contact thermal resistance. This is fundamentally different from existing technologies aimed at measuring the bulk thermal conductivity of materials, filling the gap in the accurate measurement of this specific parameter under high operating conditions. Furthermore, this method completely eliminates the parallel interference of air heat conduction through a vacuum environment, allowing the measurement results to truly reflect the actual working state under vacuum or with thermally conductive adhesive, thus significantly improving the authenticity and reliability of the data. Moreover, thanks to the high-energy-density electron beam heat source, the device can achieve extreme high-temperature measurements close to the material's melting point and can reproduce high heat flux density conditions of hundreds of watts per square centimeter, effectively solving the problem that traditional methods cannot predict actual thermal failure risks due to insufficient power. Simultaneously, the introduction of thermal insulation design and a reference method provides a dual guarantee for improved accuracy: the circumferential thermal insulation sleeve and low-emissivity aluminum foil minimize radial heat loss, while comparing steady-state data under two different power levels effectively eliminates inherent system errors, thereby achieving accurate solutions for interfacial temperature difference and heat flux density. Ultimately, the combined effect of these technical means enables the device of this invention to not only achieve breakthroughs in measurement limits and accuracy, but also ensure the high reliability of the entire measurement process and results through its self-checking functions such as one-dimensional verification, providing solid data support for the thermal design of high-end equipment. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0037] Figure 1 This is a schematic diagram of the measuring device structure described in Embodiment 1;

[0038] Figure 2 The temperature history of the AISI304 and AISI304 interface contact thermal resistance measurement experiment in the test example;

[0039] Figure 3 The results of the interface thermal resistance measurement of AISI304 and AISI304 in the test example;

[0040] Figure 4 The temperature history of the interfacial thermal resistance measurement experiment between pure copper and AISI304 in the test example;

[0041] Figure 5 The results of the interfacial thermal resistance measurement between pure copper and AISI304 in the experimental example;

[0042] In the diagram: 1. Upper pressure plate; 2. Insulating gasket; 3. Bolt; 4. Nut; 5. Water-cooled cover plate; 6. Heat-conducting block; 7. Sample A; 8. Sample B; 9. Fiber sleeve; 10. First thermocouple; 11. Second thermocouple; 12. Third thermocouple; 13. Fourth thermocouple. Detailed Implementation

[0043] The present invention will be described in detail through the following embodiments, which are intended to help those skilled in the art to more fully understand the technical solutions of the present invention, but should not be construed as limiting the scope of protection of the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0044] Example 1:

[0045] like Figure 1 As shown, the core components of the contact thermal resistance measuring device under vacuum conditions, which uses an electron beam as a heat source, are all placed inside a vacuum chamber to ensure a high vacuum measurement environment. Inside the vacuum chamber, an upper pressure plate 1 is provided, with a central through hole machined in its center. An electron beam heating unit is configured to generate a high-energy electron beam, the incident axis of which coincides with the central axis of the central through hole, allowing the electron beam to be incident perpendicularly through the hole. Directly below the central through hole, a heat-conducting block 6 is provided, its axis coaxial with the incident axis of the electron beam. Below the heat-conducting block 6, the samples to be measured, A7 and B8, are stacked coaxially and tightly below each other, forming a sample stack, the contact interface of which is the target to be measured by this device.

[0046] At the bottom of the sample stack, a water-cooling module is installed. This module includes a water-cooled cover plate 5 that directly contacts the bottom surface of sample B8 and a cooling channel integrated within it. The cooling medium flows through the cooling channel to achieve continuous cooling of the bottom of the sample stack. To minimize heat loss from the sample stack and heat-conducting block 6 during measurement, a heat insulation unit is installed circumferentially around the sides of the sample stack and heat-conducting block 6 at certain intervals. The heat insulation unit is specifically composed of an aluminum silicate fiber sleeve 9 as the main body, with high-reflectivity aluminum foil applied to its inner and outer surfaces.

[0047] In order to apply controllable axial pressure to the sample stack, the device is also equipped with a pressure application unit, which includes a bolt 3 and a nut 4. The two ends of the bolt 3 pass through the corresponding through holes on the upper pressure plate 1 and the water-cooled cover plate 5, respectively, and apply axial pressure to the stack by tightening the nut 4.

[0048] The temperature measuring unit consists of multiple temperature sensors, specifically including a first thermocouple 10 and a second thermocouple 11 installed at the upper and lower ends of sample A7, and a third thermocouple 12 and a fourth thermocouple 13 installed at the upper and lower ends of sample B8.

[0049] Finally, a control and data acquisition unit is electrically connected to the electron beam heating unit, water cooling module, pressure application unit, and temperature measurement unit, responsible for controlling the entire measurement process and acquiring and processing data. In particular, a zirconia heat insulation pad 2 is also provided between the upper pressure plate 1 and the heat-conducting block 6 to block the heat transfer from the heat-conducting block 6 to the upper pressure plate 1, protecting the upper pressure plate 1 and reducing heat loss.

[0050] In addition, the heat-conducting block 6 is preferably made of high-purity tungsten or other refractory metals with a melting point of not less than 3000K. Its diameter can be selected as 30mm and its height as 20mm. Its main function is to diffuse the concentrated point heat source of the electron beam into a uniform surface heat source, while protecting the sample under test below from direct bombardment by the electron beam.

[0051] The aluminum silicate fiber sleeve 9 in the insulation unit has a thermal conductivity of about 0.05 to 0.4 W / m / K in the temperature range of 20 to 1000℃; while the aluminum foil has a surface emissivity of about 0.02 to 0.12 W / m / K in the temperature range of 20 to 500℃. This combination of low thermal conductivity and high reflectivity can effectively suppress radial heat radiation and heat loss.

[0052] The axial pressure provided by the pressure application unit can be precisely adjusted within the range of 0 to 20 MPa. For example, different pressures such as 1 MPa, 10 MPa, or 20 MPa can be applied to simulate different assembly conditions. Multiple pressure application units 9, preferably four, are evenly distributed around the sample stack to ensure uniform pressure distribution. Of course, in addition to the aforementioned bolt 3 and nut 4 structure, other methods, including but not limited to hydraulic mechanisms, can be used to achieve opposing compression of the upper pressure plate 1 and the water-cooled cover plate 5 to meet the needs of different pressure adjustments.

[0053] The electron beam generated by the electron beam heating unit has a beam spot diameter that can be controlled within the range of 3 to 8 mm, while the accelerating voltage and beam current intensity can be adjusted according to the required heating power.

[0054] The thermocouples used in the temperature measuring unit are preferably armored thermocouples. They are inserted into the pre-drilled temperature measuring holes on sample A7 and sample B8. The axial height of each thermocouple from the upper surface of the water-cooled cover plate 5 is accurately measured and recorded. These geometric parameters are key inputs for subsequent calculations.

[0055] In summary, the measuring device, through its unique "heat-conducting block 6-sample A7-sample B8" stacked structure design, achieves direct heating and measurement of the contact interface in a vacuum environment. The combination of the heat insulation unit and the heat insulation pad 2 effectively ensures the assumption of axial one-dimensional heat transfer, while the configuration of multi-point temperature monitoring and control units lays a solid physical foundation for subsequent high-precision reference method calculations. This device can simulate extreme conditions of high temperature and high heat flux density, providing a reliable platform for the accurate measurement of contact thermal resistance.

[0056] Example 2:

[0057] This embodiment provides a specific method for measuring contact thermal resistance under vacuum conditions using the device described in Embodiment 1. The core of this method lies in accurately solving for interface parameters using a reference method based on steady-state data from two sets of different heating powers.

[0058] First, in a vacuum environment, the sample stack formed by the coaxial stacking of samples A7 and B8 is heated by irradiating the heat-conducting block 6 with an electron beam, while continuous cooling is provided by a water-cooling module, allowing the system to establish its first steady-state temperature field. At this time, the control and data acquisition unit controls the electron beam heating unit to heat at a specific initial power and monitors the temperature readings of all thermocouples until the temperature change is less than a threshold within a preset time window, at which point thermal steady state is considered to have been reached.

[0059] Next, the axial temperature data of sample A7 and sample B8 under the first steady state are obtained through the temperature measuring unit, that is, the temperature of the first thermocouple 10 is recorded. The temperature of the second thermocouple 11 The temperature of the third thermocouple 12 And the temperature of the fourth thermocouple 13 .

[0060] Then, the electron beam heating power is changed to a second, different value, for example, increasing the beam current from 10mA to 15mA, and then the system is allowed to reach thermal equilibrium again to establish a second steady-state temperature field. Similarly, the corresponding second set of axial temperature data is acquired and recorded, denoted as... , , , .

[0061] After obtaining two sets of steady-state data, the core calculation step begins. This step uses the first set of steady-state data as a reference, combined with the two sets of steady-state temperature data, to solve for the temperature at the interface between sample A7 and sample B8 using a reference method. and and interfacial heat flux density The specific calculation process is as follows:

[0062] First, it is necessary to know the functional relationship between the thermal conductivity of sample A7 and sample B8 and temperature, i.e. and These relationships can be obtained in advance through literature review or other standard experiments.

[0063] Based on the assumption of one-dimensional axial steady-state heat transfer, the heat flux density of sample A7 and sample B8 is... and The results can be obtained by integrating the thermal conductivity over the corresponding temperature range.

[0064] Specifically, through the heat flux density of sample A7 The calculation formula is: ,in and The heights of the first thermocouple 10 and the second thermocouple 11 from the water-cooled cover plate 5 are respectively.

[0065] Similarly, the heat flux density of sample B8 The calculation formula is: ,in and The heights of the third thermocouple 12 and the fourth thermocouple 13 from the water-cooled cover plate 5 are respectively.

[0066] In the calculation and Afterwards, the one-dimensional heat transfer assumption needs to be verified, that is, calculations are required. ,in The average heat flux density at the interface is calculated using the following formula: If the relative deviation is ≤5%, the one-dimensional heat transfer assumption is considered valid, and subsequent calculations can be performed. Of course, this 5% threshold is optional; depending on the measurement accuracy requirements, it can also be set to a more lenient 10% or a more stringent 2%.

[0067] The changes in heat flux density through sample A7 and sample B8 caused by the change in heating power are as follows:

[0068] ; ;

[0069] The change in heat flux density at the contact surface between samples A7 and B8 caused by the change in heating power can be expressed as:

[0070] ;

[0071] Based on Fourier's heat conduction formula, the contact surface between samples A7 and B has the following equation:

[0072] ;

[0073] ;

[0074] in, The height of the contact surfaces of samples A7 and B from the water-cooled cover plate 5. and Sample A7 and sample respectively

[0075] B8 is the temperature at the contact surface.

[0076] Solving the above two systems of equations yields the following results. and Then the contact thermal resistance between samples A7 and B and interface temperature It can be represented as:

[0077] ;

[0078] .

[0079] In this process, the interface temperature is solved. and At that time, it was based on the thermal conductivity of sample A7 and sample B8. and The dependence on temperature is achieved by integrating the axial heat flow.

[0080] Finally, according to the definition formula of contact thermal resistance Calculate the contact thermal resistance between the interface of sample A7 and sample B8. .

[0081] In summary, the measurement method provided in this embodiment effectively reduces systematic errors by introducing a reference method and closely integrating temperature-dependent thermophysical properties, achieving high-precision solutions for interface temperature difference and heat flux density. When used in conjunction with the dedicated measurement device described in Embodiment 1, this method can achieve measurement accuracy and reliability that are difficult to attain with traditional methods, especially under high temperature and high heat flux density conditions.

[0082] Experimental example:

[0083] To more fully illustrate the feasibility and advantages of Example 1 and Example 2 in contact thermal resistance measurement, we conducted the following experimental results.

[0084] First, prepare the test samples. Select two AISI 304 stainless steel cylinders, each 30mm in diameter and height, and mechanically polish their end faces. These will be designated as samples A7 and B8, respectively. Drill two temperature measurement holes along the axis of sample A7, ensuring an axial spacing of 13mm between the two thermocouples. Similarly, drill two temperature measurement holes on sample B8, with an axial spacing of 20mm. During installation, ensure that the contact interface between samples A7 and B8 is 15mm from the second thermocouple 11 at the bottom of sample A7 and 5mm from the third thermocouple 12 at the top of sample B8.

[0085] Next, following the layout and assembly method described in Example 1, samples A7 and B8 are stacked sequentially from top to bottom and installed into the measuring device. A pressure of 10 MPa is applied through the surrounding fastening bolts 3. All armored thermocouples are inserted into their corresponding temperature measuring holes.

[0086] Next, heating experiments were conducted. The assembled test setup was placed in the vacuum chamber of the electron beam heating equipment and evacuated to a high vacuum. The electron beam accelerating voltage was fixed at 49.8 kV, and the heating power was adjusted by changing the electron beam current. The electron beam power was gradually increased from 5 mA, 8 mA to 11 mA, and the sample was continuously heated at each power point until the system reached thermal steady state.

[0087] The control and data acquisition unit automatically records the temperature change history of each thermocouple over time.

[0088] Figure 2 The temperature history curve of the AISI304 interface contact thermal resistance measurement experiment is shown. The horizontal axis of the graph is time and the vertical axis is temperature. It can be clearly seen that the temperature of each measuring point gradually rises under different heating powers and eventually reaches a stable plateau.

[0089] Finally, the contact thermal resistance is calculated. The control and data acquisition unit calls the pre-stored AISI304 thermal conductivity formula. and based on Figure 2The steady-state temperature data extracted from each temperature measurement point were used as a reference, with the steady-state temperature of the first group of lower power as a reference. The calculation process described in Example 2 was followed, including the calculation of heat flux density. and Verify the one-dimensional heat transfer assumption and calculate the change in heat flux. and Solving the interface temperature based on the Fourier heat conduction formula and Finally, based on the contact thermal resistance formula The contact thermal resistance was calculated.

[0090] The contact thermal resistance between AISI304 and AISI304 in the temperature range of 550K to 720K was calculated when high-temperature thermally conductive adhesive was applied between the interfaces under vacuum conditions. Figure 3 The graph shows the measured contact thermal resistance at the AISI304 interface. The horizontal axis represents the average interface temperature, and the vertical axis represents the contact thermal resistance. The graph shows that within this temperature range, the contact thermal resistance is approximately 2200 × 10⁻⁶. -6 ~3400×10 -6 K·m 2 The contact thermal resistance is between / K, and as the interface temperature increases, the contact thermal resistance shows a certain trend of change.

[0091] To further demonstrate the applicability of the invention, measurements of dissimilar material interfaces can also be performed. For example, a pure copper pillar and an AISI 304 pillar, both 30 mm in diameter and height, are prepared and polished to serve as samples A7 and B8, respectively. The above test procedure is repeated.

[0092] The thermal conductivity of pure copper is expressed by the formula... Perform the calculation. Figure 4 and Figure 5 The temperature history curves and final contact thermal resistance measurement results for the interface thermal resistance of pure copper and AISI304 are presented respectively. From... Figure 5 It can be seen that, over a wider temperature range of 650–920 K, the contact thermal resistance between pure copper and AISI304 is approximately 570 × 10⁻⁶. -6 ~920×10 -6 K·m 2 / K.

[0093] This experimental example, through a complete experimental procedure and specific data charts, fully verifies the feasibility and effectiveness of the apparatus in Implementation 1 and the method in Implementation 2 in practical applications. It can not only accurately measure the contact thermal resistance of interfaces of the same material, but also handle the measurement tasks of combinations of dissimilar materials. The obtained data shows good repeatability and strong regularity, providing a highly valuable reference for engineering applications.

Claims

1. A device for measuring contact thermal resistance under vacuum conditions using an electron beam as a heat source, characterized in that, include: The vacuum chamber provides a vacuum environment for the entire measuring device; An upper pressure plate (1) is disposed in the vacuum cavity, and the upper pressure plate (1) has a central through hole; An electron beam heating unit is used to generate an electron beam, which is incident through the central through-hole; A heat-conducting block (6) is disposed below the upper pressure plate (1) and is coaxial with the incident electron beam axis; The sample stack consists of sample A (7) and sample B (8) that are coaxially and in close contact from top to bottom. The sample stack is located below the heat-conducting block (6) to form the contact interface to be tested. A water-cooling module is located below the sample stack and includes a water-cooling cover plate (5) and its internal cooling channels for cooling the bottom of sample B (8). The thermal insulation unit, which circumferentially encloses the stacked sample body, is used to reduce radial heat loss; A pressure application unit is used to apply axial pressure to the sample stack; The temperature measuring unit includes a first thermocouple (10) and a second thermocouple (11) set at the upper and lower ends of sample A (7), and a third thermocouple (12) and a fourth thermocouple (13) set at the upper and lower ends of sample B (8). The control and data acquisition unit is configured to: control the electron beam heating unit to heat to steady state under two different power levels, acquire the steady-state temperature of each thermocouple, and calculate the contact thermal resistance between the interface of sample A (7) and sample B (8) based on the reference method.

2. The contact thermal resistance measuring device under vacuum conditions using an electron beam as a heat source according to claim 1, characterized in that, The pressure application unit includes a bolt (3) and a nut (4). The two ends of the nut (4) pass through the upper pressure plate (1) and the water-cooled cover plate (5) respectively and are threadedly connected to the nut (4). An adjustable pressure of 0 MPa to 20 MPa is applied to the sample stack by adjusting the spacing between the two nuts (4); Multiple pressure application units are evenly distributed around the sample stack.

3. The contact thermal resistance measuring device under vacuum conditions using an electron beam as a heat source according to claim 1, characterized in that, The heat insulation unit includes an aluminum silicate fiber sleeve (9) and aluminum foil applied to the inner and outer surfaces of the aluminum silicate fiber sleeve (9).

4. The vacuum-condition contact thermal resistance measuring device using an electron beam as a heat source according to claim 1, characterized in that, A zirconium oxide heat insulation pad (2) is provided between the upper pressure plate (1) and the heat-conducting block (6).

5. The contact thermal resistance measuring device under vacuum conditions using an electron beam as a heat source according to claim 1, characterized in that, The electron beam generated by the electron beam heating unit has a beam spot diameter of 3 mm to 8 mm.

6. The contact thermal resistance measuring device under vacuum conditions using an electron beam as a heat source according to claim 1, characterized in that, The control and data acquisition unit is configured to calculate the axial heat flux density of samples A (7) and B (8) respectively, based on the relationship between thermal conductivity and temperature, when performing the reference method calculation. and and in At that time, it is assumed that the one-dimensional heat transfer assumption is satisfied, where The average heat flux density at the interface.

7. A method for measuring contact thermal resistance under vacuum conditions using the apparatus described in any one of claims 1-6, characterized in that, Includes the following steps: S1. In a vacuum environment, the sample stack formed by the coaxial stacking of sample A (7) and sample B (8) is heated by irradiating the heat-conducting block (6) with an electron beam, and cooled by the water-cooling module to establish the first steady-state temperature field; S2. Obtain the axial temperature data of sample A (7) and sample B (8) under the first steady state through the temperature measurement unit; S3. Change the electron beam heating power to establish a second steady-state temperature field and obtain the corresponding second set of axial temperature data; S4. Using the first set of steady-state data as a reference, and combining the two sets of steady-state temperature data, the temperature at the interface between sample A (7) and sample B (8) is solved using the reference method. and and interfacial heat flux density ; S5. According to the formula Calculate the contact thermal resistance.

8. The method for measuring contact thermal resistance under vacuum conditions using an electron beam as a heat source according to claim 7, characterized in that, In step S4, the interface temperature is calculated. and At that time, based on the thermal conductivity of sample A (7) and sample B (8) and The dependence on temperature is calculated by integrating the axial heat flux density.

9. The method for measuring contact thermal resistance under vacuum conditions using an electron beam as a heat source according to claim 7, characterized in that, Before step S4, a one-dimensional heat transfer assumption verification step is also included: calculating the axial heat flux density of sample A(7). Axial heat flux density of sample B(8) If the relative deviation exceeds the preset threshold, the measurement is deemed invalid. The preset threshold is 2% to 10%.

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