Test fixture and system for stacked cable superconducting conductors

Abstract

The application provides a test tool and system for a stacked cable superconducting conductor, wherein the test tool for the stacked cable superconducting conductor comprises a clamping structure, a stacked cable superconducting conductor and a superconducting tape stack layer, the clamping structure comprises a lower substrate and a clamping terminal, the superconducting tape stack layer is matched with the width of the stacked cable superconducting conductor, and the superconducting tape stack layer is matched with the length of the clamping terminal; the lower substrate is provided with a positioning groove matched with the width of the stacked cable superconducting conductor on the upper interface; the clamping terminal is provided with a convex body matched with the width of the positioning groove on the lower interface, and is provided with a tape assembly groove on the upper surface; wherein the clamping space is formed between the lower substrate and the clamping terminal, the end part of the stacked cable superconducting conductor is clamped between the lower substrate and the clamping terminal in a matched mode through cooperation of the positioning groove and the convex body, the superconducting tape stack layer is embedded in the tape assembly groove, the overall stacked cable superconducting conductor is uniformly passed through, the test data truly reflecting the current-carrying performance of the stacked cable superconducting conductor can be obtained, and the accuracy of the test is improved.

Description

Technical Field

[0001] This application relates to the field of superconducting technology, and in particular to a testing fixture and system for a stacked cable superconducting conductor. Background Technology

[0002] With the development of superconducting conductor material preparation technology, single superconducting conductors have certain limitations in practical applications, such as limited current carrying capacity, significant attenuation of critical current under vertical magnetic fields, and high brittleness, posing a risk of quenching. By stacking multiple superconducting conductors together to form stacked cable superconducting conductors, the current carrying capacity, mechanical strength, and magnetic field performance can be effectively improved, while maintaining superconducting properties. The demand for stacked cable superconducting conductors as core materials in nuclear fusion, power transmission systems, and high-field magnets has increased significantly.

[0003] Currently, current-carrying capacity and stability under strong magnetic fields and high current conditions can be evaluated by conducting current-carrying tests on stacked cable superconducting conductors. As a core step in verifying the current-carrying capacity and stability of superconducting conductors, studying uniform current flow is essential.

[0004] However, in the current testing fixtures for stacked cable superconducting conductors, the current mainly enters the superconducting conductor near the injection end. At this time, the current is concentrated on one side near the injection end. The clamping terminals have a certain resistance, and the farther away, the greater the resistance of the clamping terminals. This resistance is often greater than the resistance of shunting current from one superconducting conductor to another in the stack. As a result, the current will flow through the superconducting conductor instead of through the clamping terminals. This causes the superconducting conductor near the injection end to receive current first, and the superconducting conductor farther away from the injection end to receive current later, resulting in uneven current shunting. This leads to uneven current flow in the entire stacked cable superconducting conductor, which in turn causes distortion of the current flow test data of the stacked cable superconducting conductor. Utility Model Content

[0005] This application provides a test fixture for stacked cable superconducting conductors, which can achieve uniform current flow throughout the stacked cable superconducting conductor, thereby obtaining test data that truly reflects the current-carrying performance of the stacked cable superconducting conductor and improving the accuracy of the test.

[0006] According to one aspect of the embodiments of this application, a test fixture for a stacked cable superconducting conductor is provided, including a clamping structure, a stacked cable superconducting conductor, and a superconducting tape stack layer. The clamping structure includes a lower substrate and clamping terminals. The width of the superconducting tape stack layer matches that of the stacked cable superconducting conductor, and the length of the superconducting tape stack layer matches that of the clamping terminals.

[0007] The lower substrate has a positioning groove on its upper interface that matches the width of the superconducting conductor of the stacked cable.

[0008] The clamping terminal has a protrusion on its lower interface that matches the width of the positioning groove, and a strip assembly groove on its upper surface.

[0009] The positioning groove and the protrusion work together to clamp the end of the superconducting conductor of the stacked cable between the lower substrate and the clamping terminal, and the superconducting tape stack layer is embedded in the tape assembly groove.

[0010] According to another aspect of the embodiments of this application, a testing system for a stacked cable superconducting conductor is provided, including the testing fixture, cryogenic container and data acquisition system of the stacked cable superconducting conductor described above;

[0011] The test fixture is immersed in the cryogenic fluid in the cryogenic container and is electrically connected to the data acquisition system.

[0012] In one embodiment of this application, a test fixture for a stacked cable superconducting conductor is provided. The end of the stacked cable superconducting conductor is tightly fixed within a clamping space formed by the positioning groove of the lower substrate and the protrusion of the clamping terminal. The fixture structure is simple and reliable. Furthermore, a superconducting tape stack layer is embedded in the tape assembly groove of the clamping terminal, constructing a composite conductive structure composed of the superconducting tape stack layer and the clamping terminal. When current is injected from the clamping terminals, an equipotential surface is first formed in the horizontal direction of the superconducting tape stack, allowing the current to be evenly distributed across the entire cross-section of the superconducting tape stack. Subsequently, the current is conducted vertically downwards to the superconducting conductor of the stacked cable. Since the contact resistance between the superconducting tape stack and the clamping terminals is equalized through the equipotential surface, the vertical resistance is kept consistent, allowing the current to be synchronously and proportionally shunted to the superconducting conductor of the stacked cable. This eliminates the resistance gradient effect caused by distance in traditional testing fixtures, solves the problem of uneven current distribution in the superconducting conductor of the stacked cable, and achieves uniform current flow throughout the superconducting conductor of the stacked cable. As a result, test data that truly reflects the current-carrying performance of the superconducting conductor of the stacked cable can be obtained, improving the accuracy of the test. Attached Figure Description

[0013] Figure 1 This is a simulation diagram of the current distribution of a stacked cable superconducting conductor in a test fixture for a stacked cable superconducting conductor.

[0014] Figure 2 This is a schematic diagram of the structure of a test fixture for a stacked cable superconducting conductor provided in one embodiment of this application;

[0015] Figure 3 This is one of the structural schematic diagrams of a stacked cable superconducting conductor in a test fixture provided in an embodiment of this application;

[0016] Figure 4 This is one of the structural schematic diagrams of the lower substrate in a test fixture for a stacked cable superconducting conductor provided in an embodiment of this application;

[0017] Figure 5 This is one of the structural schematic diagrams of a test fixture for holding terminals in a stacked cable superconducting conductor according to an embodiment of this application;

[0018] Figure 6 This is one of the structural schematic diagrams of the superconducting tape stack layer in a test fixture for a stacked cable superconducting conductor provided in an embodiment of this application;

[0019] Figure 7 This is a schematic diagram of the structure of a stepped protrusion in a test fixture for a stacked cable superconducting conductor provided in one embodiment of this application;

[0020] Figure 8 This is a schematic diagram of the step-by-step bonding structure in a test fixture for a stacked cable superconducting conductor provided in one embodiment of this application;

[0021] Figure 9 This is a second schematic diagram of the structure of the superconducting tape stack layer in a test fixture for a stacked cable superconducting conductor provided in an embodiment of this application;

[0022] Figure 10 This is a second schematic diagram of the structure of a stacked cable superconducting conductor in a test fixture provided in an embodiment of this application;

[0023] Figure 11 This is a second schematic diagram of the structure of the terminal clamping device in a test fixture for a stacked cable superconducting conductor provided in an embodiment of this application;

[0024] Figure 12 This is a schematic diagram of the fastener connection structure in a test fixture for a stacked cable superconducting conductor provided in an embodiment of this application;

[0025] Figure 13 This is a schematic diagram of the armor structure in a test fixture for a stacked cable superconducting conductor provided in one embodiment of this application;

[0026] Figure 14 This is a simulation diagram of the current distribution of a stacked cable superconducting conductor in a test fixture provided in an embodiment of this application;

[0027] Figure 15 This is a schematic diagram of the structure of a test system for a stacked cable superconducting conductor provided in one embodiment of this application;

[0028] Figure 16 This is a flowchart of a testing method for a stacked cable superconducting conductor provided in one embodiment of this application.

[0029] Figure Labels

[0030] Test system for stacked cable superconducting conductors - 1; Test fixture for stacked cable superconducting conductors - 10; Cryogenic container - 20; Data acquisition system - 30; Clamping structure - 110; Stacked cable superconducting conductor - 120; Superconducting tape stacking layer - 130; Armor - 140; Lower substrate - 1110; Clamping terminal - 1120; Fastener - 1130; Positioning groove - 11110; Protrusion - 11210; Tape assembly groove - 11220; Through hole - 11230; Stacked cable - 1210; Superconducting tape - 1310. Detailed Implementation

[0031] Many specific details are set forth in the following description to provide a full understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of this application; therefore, this application is not limited to the specific embodiments disclosed below.

[0032] The terminology used in one or more embodiments of this application is for the purpose of describing particular embodiments only and is not intended to limit the scope of the one or more embodiments of this application. The singular forms “a,” “the,” and “the” used in one or more embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” used in one or more embodiments of this application refers to and includes any or all possible combinations of one or more associated listed items. The term “at least one” in one or more embodiments of this application means “one or more,” and “a plurality of” means “two or more.” The term “comprising” is an open-ended description and should be understood as “including but not limiting,” and may include other content in addition to what has been described.

[0033] It should be understood that although the terms "first," "second," etc., may be used to describe various information in one or more embodiments of this application, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, "first" may also be referred to as "second" without departing from the scope of one or more embodiments of this application, and similarly, "second" may also be referred to as "first." Depending on the context, the word "if," as used herein, may be interpreted as "when," "in response to a determination," or "when," or "in the event of a determination."

[0034] First, the terms and concepts involved in one or more embodiments of this application will be explained.

[0035] Superconductivity: refers to the physical phenomenon that certain materials suddenly lose their electrical resistance under specific low-temperature conditions, and at the same time become completely diamagnetic to external magnetic fields (Meissner effect). At this time, the material can transmit current without loss.

[0036] Superconductor: A conductor made of superconducting material that can achieve zero resistance current carrying in the superconducting state. It usually needs to operate at critical temperature, magnetic field and current density.

[0037] Stacked cable: A conductor structure that integrates multiple superconducting tapes (such as REBCO) through layered stacking or stranding, designed to improve overall current carrying capacity, mechanical strength and magnetic field stability.

[0038] Critical current (Ic): The maximum current that a superconducting material can carry while maintaining its superconducting state. Exceeding this value will cause it to lose superconductivity (exit the superconducting state) and recover its resistance. It is the core parameter for evaluating the current-carrying performance of a superconducting conductor.

[0039] REBCO tape: A second-generation high-temperature superconducting material composed of rare earth (RE)-barium (Ba)-copper (Cu) oxide (ReBCO), it features high critical current density and stable performance under strong magnetic fields, and is often made into a flexible tape structure.

[0040] With the development of superconducting conductor material preparation technology, single superconducting conductors have certain limitations in practical applications, such as limited current carrying capacity, significant attenuation of critical current under vertical magnetic fields, and high brittleness, posing a risk of quenching. By stacking multiple superconducting conductors together to form stacked cable superconducting conductors, the current carrying capacity, mechanical strength, and magnetic field performance can be effectively improved, while maintaining superconducting properties.

[0041] Stacked cable superconductors possess unique physical properties and engineering advantages. Based on second-generation REBCO tape, stacked cable superconductors exhibit superior current-carrying capacity in the liquid nitrogen region. Furthermore, through optimized and innovative structural design, stacked cable superconductors have achieved significant results in reducing AC losses and increasing mechanical properties. With its high current-carrying capacity, strong field stability, and low loss, the demand for stacked cable superconductors is significantly increasing in applications such as nuclear fusion, power transmission systems, and as a core material for high-field magnets. With decreasing costs and advancements in manufacturing technology, stacked cable superconductors will achieve large-scale applications in energy, medical, and transportation fields in the future. To provide direction for improving the materials and optimizing the structure of stacked cable superconductors and ensure their engineering reliability, testing their critical current (Ic) and other current-carrying properties is essential.

[0042] The ends of stacked cable superconducting conductors typically employ a stepped structure design. This stepped structure enhances the current-carrying capacity of the superconducting conductor, optimizes current distribution to avoid localized overheating, and increases the mechanical strength of the stacked cable, enabling it to withstand greater bending and tensile stresses. However, current testing fixtures for the current-carrying performance of stacked cable superconducting conductors simply clamp the conductors, resulting in significant defects such as uneven current flow. Since uniform current flow is a primary indicator for evaluating the performance of testing fixtures, technological advancements in this area will directly drive the application of stacked cable superconducting conductors. Figure 1 A simulation diagram of the current distribution of a stacked cable superconducting conductor in a test fixture is shown:

[0043] The stacked cable superconducting conductors are held in place by clamping terminals and a lower substrate. Current needs to be introduced into the stacked cable superconducting conductors far from the injection end of the test fixture. The current mainly enters the stacked cable superconducting conductors from the side closer to the injection end and is concentrated on the side closer to the injection end. However, the clamping terminals have a certain resistance. The farther away the distance, the greater the resistance of the clamping terminals. It is often greater than the resistance of shunting current from one superconducting conductor to another in the stack. At this time, the current will be introduced through the superconducting conductors instead of from the clamping terminals. This causes the superconducting conductors closer to the injection end to receive current first, and the superconducting conductors farther from the injection end to receive current later, resulting in uneven current shunting.

[0044] like Figure 1 The current distribution shown causes uneven current flow in the superconducting conductor of the stacked cable, which in turn leads to distortion of the current flow test data of the superconducting conductor of the stacked cable.

[0045] This application provides a test fixture for stacked cable superconducting conductors, which can achieve uniform current flow throughout the stacked cable superconducting conductor, thereby obtaining test data that truly reflects the current-carrying performance of the stacked cable superconducting conductor and improving the accuracy of the test.

[0046] Figure 2 This illustration shows a schematic diagram of a test fixture 10 for a stacked cable superconducting conductor according to an embodiment of this application. The test fixture 10 for the stacked cable superconducting conductor 120 includes a clamping structure 110, a stacked cable superconducting conductor 120, and a superconducting tape stack layer 130. The clamping structure 110 includes a lower substrate 1110 and a clamping terminal 1120. The width of the superconducting tape stack layer 130 matches that of the stacked cable superconducting conductor 120, and the length of the superconducting tape stack layer 130 matches that of the clamping terminal 110.

[0047] The lower substrate 1110 has a positioning groove 11110 on its upper interface that matches the width of the superconducting conductor 120 of the stacked cable.

[0048] The clamping terminal 1120 has a protrusion 11210 on its lower interface that matches the width of the positioning groove 11110, and a strip assembly groove 11220 on its upper surface.

[0049] The positioning groove 11110 and the protrusion 11210 cooperate to attach and clamp the end of the superconducting conductor 120 of the stacked cable between the lower substrate 1110 and the clamping terminal 1120, and the superconducting tape stack layer 130 is embedded in the tape assembly groove 11220.

[0050] The test fixture 10 for the stacked cable superconducting conductor 120 is a device for measuring the current carrying capacity of the stacked cable superconducting conductor 120. The test fixture 10 achieves uniform current distribution across the conductor cross-section through the composite conductive structure of the superconducting tape stack layer 130 and the clamping terminal 1120, eliminating the contact resistance gradient caused by traditional clamping and ensuring that the test data reflects the true current carrying capacity.

[0051] The stacked cable superconducting conductor 120 is a composite conductor structure integrated by stacking multiple layers of superconducting conductors. The material of the stacked cable superconducting conductor 120 can be REBCO tape, Bi-2223 tape, NbTi wire, or MgB2 wire, etc. The stacked cable superconducting conductor 120 reduces local current density through geometric optimization, avoiding the critical current limitation of a single superconducting conductor, while simultaneously improving mechanical performance through mechanical coupling. For example, the REBCO stacked cable superconducting conductor 120 used in nuclear fusion devices consists of 10 layers of superconducting conductors stacked and then copper-clad. Optionally, the stacked cable superconducting conductor 120 includes one or more sets of parallel-arranged stepped stacked cables 1210. Optionally, the ends of the stacked cable superconducting conductor 120 can be stepped, planar, or inclined. Taking a stepped shape as an example... Figure 3 This illustration shows one of the structural schematic diagrams of a stacked cable superconducting conductor in a test fixture provided in an embodiment of this application: the stacked cable superconducting conductor 120 integrates multiple superconducting conductors in a stacked manner to form a stepped end.

[0052] The clamping structure 110 is a fixing assembly for the stacked cable superconducting conductor 120, which is composed of a lower substrate 1110 and clamping terminals 1120. It is used to rigidly fix the end of the stacked cable superconducting conductor 120 and establish a low-resistance electrical connection. In the clamping structure 110, the positioning groove 11110 and the protrusion 11210 cooperate to achieve precise alignment of the stacked cable superconducting conductor 120, while providing sufficient clamping force to avoid contact resistance fluctuations.

[0053] The lower substrate 1110 serves as the support base for the clamping structure 110. Its upper surface is provided with a positioning groove 11110 for positioning the stacked cable superconducting conductor 120. The width of the positioning groove 11110 matches the conductor (e.g., tolerance ±0.1 mm) to ensure that the stacked cable superconducting conductor 120 does not undergo significant displacement within the clamping structure 110, simulating real-world engineering conditions and improving the validity of test data. The positioning groove 11110 is a rectangular groove formed on the upper surface of the lower substrate 1110, and its width matches the width of the stacked cable superconducting conductor 120. Optionally, the groove walls of the positioning groove 11110 are polished to reduce frictional loss, and the bottom of the groove has anti-slip textures. Figure 4 The following is a schematic diagram of the structure of the lower substrate in a test fixture for a stacked cable superconducting conductor provided in one embodiment of this application: the lower substrate 1110 is a rectangular plate structure, and there is a rectangular groove in the center of its upper surface, which is the positioning groove 11110.

[0054] The clamping terminal 1120 is a conductive block in the clamping structure 110 that mates with the lower substrate 1110. Its lower surface has a protrusion 11210, and its upper surface has a strip assembly groove 11220 for embedding the superconducting strip stack 130. The protrusion 11210 is a protruding structure on the lower surface of the clamping terminal 1120 corresponding to the positioning groove 11110, and its cross-sectional shape is complementary to that of the positioning groove 11110. The height of the protrusion 11210 is typically slightly greater than the depth of the positioning groove 11110 (e.g., a difference of 0.2-0.5 mm) to ensure that the superconducting conductor 120 of the stacked cable is sufficiently compressed during clamping. Optionally, the protrusion 11210 can be stepped, planar, or inclined. For example, a trapezoidal inclined protrusion 11210 has a top width 0.3 mm narrower than the positioning groove 11110. The strip assembly groove 11220 is a rectangular groove in the center of the upper surface of the clamping terminal 1120, which is used to accommodate the superconducting strip stack 130 and establish an equipotential surface. Figure 5 This document shows one of the structural schematic diagrams of a clamping terminal in a test fixture for a stacked cable superconducting conductor provided in an embodiment of this application: the clamping terminal 1120 is a rectangular protruding structure with a rectangular groove at the center of its upper surface, which is the strip assembly groove 11220, and a protrusion 11210 at the center of its lower surface.

[0055] The superconducting conductor 120 of the stacked cable is limited by the positioning groove 11110 on the lower substrate 1110 and the protrusion 11210 of the clamping terminal 1120, so that its test condition is more in line with the actual engineering situation and the validity of the obtained data is enhanced.

[0056] The superconducting tape stack 130 is a composite conductive structure composed of multiple layers of superconducting tapes 1310 horizontally stacked. The material of the superconducting tape stack 130 can be REBCO tape, Bi-2223 tape, NbTi wire, or MgB2 wire, etc. The superconducting tape stack 130 is embedded in the tape assembly groove 11220 of the clamping terminal 1120, utilizing its superconducting properties (zero resistance) to form a horizontal equipotential surface, ensuring uniform current injection into the superconducting conductor 120 of the stacked cable. The superconducting tapes 1310 in the superconducting tape stack 130 can be connected to each other with low resistance through metal plating (such as silver or copper) or low-temperature solder (such as indium tin alloy), reducing interlayer contact resistance. For example, 10 layers of REBCO tape are horizontally stacked, with silver plating between the layers to form the superconducting tape stack 130, which is then embedded in the tape assembly groove 11220 of the clamping terminal 1120. Figure 6 This illustration shows one of the structural schematic diagrams of a superconducting tape stack layer in a test fixture for a stacked cable superconducting conductor according to an embodiment of this application: the superconducting tape stack layer 130 presents a strip-shaped structure, and the width of the superconducting tape stack layer 130 matches that of the stacked cable superconducting conductor 120.

[0057] For example, the stacked cable superconducting conductor 120 is a stack of 10 layers of REBCO, with a single layer thickness of 0.2 mm and a width of 12 mm. The superconducting tape stack 130 is a stack of 20 parallel REBCO tapes, with a single layer thickness of 0.1 mm and a width of 12 mm. In the clamping structure 110 of the test fixture 10 for the stacked cable superconducting conductor 120, the lower substrate 1110 is made of copper and has dimensions of 150 mm (L) × 50 mm (W) × 20 mm (H). The positioning groove 11110 on its upper surface has a width of 12.0 ± 0.05 mm and a depth of 3 mm. The clamping terminal 1120 is made of copper, with a protrusion 11210 on its lower surface having a width of 11.8 mm and a height of 3.3 mm. The tape assembly groove 11220 on its upper surface has dimensions of 12 mm × 2 mm × 80 mm. The positioning groove 11110 and the protrusion 11210 cooperate to attach and clamp the end of the superconducting conductor 120 of the stacked cable between the lower substrate 1110 and the clamping terminal 1120, and the superconducting tape stack layer 130 is embedded in the tape assembly groove 11220.

[0058] In this embodiment, the end of the superconducting conductor 120 of the stacked cable is tightly fixed within the clamping space formed by the positioning groove 11110 of the lower substrate 1110 and the protrusion 11210 of the clamping terminal 1120, resulting in a simple and reliable tooling structure. Furthermore, a superconducting tape stack layer 130 is embedded in the tape assembly groove 11220 of the clamping terminal 1120, constructing a composite conductive structure composed of the superconducting tape stack layer 130 and the clamping terminal 1120. When current is injected from the clamping terminal 1120, an equipotential surface is first formed in the horizontal direction of the superconducting tape stack 130, so that the current is evenly distributed to the entire cross-section of the superconducting tape stack 130. Then the current is conducted vertically downward to the stacked cable superconducting conductor 120. Since the contact resistance between the superconducting tape stack 130 and the clamping terminal 1120 is equalized through the action of the equipotential surface, the vertical resistance is consistent, so that the current can be synchronously and proportionally distributed to the stacked cable superconducting conductor 120. This eliminates the resistance gradient effect caused by distance in the traditional test fixture 10, solves the problem of uneven current distribution in the stacked cable superconducting conductor 120, and realizes uniform current flow in the entire stacked cable superconducting conductor 120. Thus, test data that truly reflects the current carrying performance of the stacked cable superconducting conductor 120 can be obtained, improving the accuracy of the test.

[0059] If a simple clamping method is used, such as using a parallel lower substrate 1110 and clamping terminals 1120, without considering the stepped structure at the end of the stacked cable superconducting conductor 120, the uniformity of current flow will also be affected. Furthermore, the curves measured by the test fixture 10 using this simple clamping structure 110 often show resistive voltages, which severely distorts the current flow test data of the stacked cable superconducting conductor 120.

[0060] Specifically, in one optional embodiment of this application, the protrusion 11210 is stepped, and the end of the stacked cable superconducting conductor 120 is stepped;

[0061] The positioning groove 11110 and the stepped protrusion 11210 cooperate to clamp the stepped end of the stacked cable superconducting conductor 120 between the lower substrate 1110 and the clamping terminal 1120.

[0062] The stepped protrusion 11210 is a stepped protrusion structure with multiple height differences, corresponding to the lower surface of the clamping terminal 1120 and the positioning groove 11110. Its cross-section has a layered decreasing geometric shape, and the width and height of each step are designed to match the end of the stacked cable superconducting conductor 120. By clamping the stepped protrusion 11210 step by step, the end of the entire stacked cable superconducting conductor 120 is fully in contact with the clamping terminal 1120, which applies uniform force to the end of the stacked cable superconducting conductor 120, avoids stress concentration at a single point, and effectively improves the problem of uneven current flow. Figure 7The diagram shows a stepped protrusion in a test fixture for a stacked cable superconducting conductor according to an embodiment of this application: a strip assembly groove 11220 is provided on the upper surface of the clamping terminal 1120, and a 6-level stepped protrusion 11210 is provided at the center of its lower surface.

[0063] The stepped end is a stepped structure formed by rolling the end of the stacked cable superconducting conductor 120. Its cross-section has a geometric shape with decreasing layers. This structure optimizes the current distribution of the stacked cable superconducting conductor 120 and improves mechanical stability by increasing the contact area and layered current conduction path.

[0064] Figure 8 This illustration shows a schematic diagram of the step-by-step bonding structure in a test fixture for a stacked cable superconducting conductor according to an embodiment of this application:

[0065] The positioning groove 11110 and the stepped protrusion 11210 cooperate to attach and clamp the stepped end of the stacked cable superconducting conductor 120 between the lower substrate 1110 and the clamping terminal 1120. At this time, the six-level stepped protrusion 11210 on the lower surface of the clamping terminal 1120 and the six-level stepped end of the stacked cable superconducting conductor 120 are attached one-to-one.

[0066] The above Figure 8 The step-by-step bonding method involves laying the superconducting tape stack 130 flat on the upper surface of the clamping terminal 1120. When energized, the superconducting tape stack 130 in the clamping terminal 1120 receives current and forms an equipotential surface on the horizontal superconducting layer. Then, the current flows downward into the end of the stepped stacked cable superconducting conductor 120. The terminal resistance through which the current flows downward at different positions is almost the same. Therefore, each level of superconducting conductor at the stepped end of the stacked cable superconducting conductor 120 can receive current almost simultaneously, achieving uniform current flow.

[0067] For example, the height of each step of the stepped end of the stacked cable superconducting conductor 120 is H=0.2 mm. Correspondingly, the stepped protrusion 11210 is designed with 6 steps, and the height difference of each step is Δh=0.2 mm. The positioning groove 11110 cooperates with the stepped protrusion 11210 to fit and clamp the stepped end of the stacked cable superconducting conductor 120 between the lower substrate 1110 and the clamping terminal 1120.

[0068] In this embodiment, a stepped structure is added to the protrusion 11210, corresponding to the stepped end of the stacked cable superconducting conductor 120, so that the stacked cable superconducting conductor 120 can be more tightly clamped between the lower substrate 1110 and the clamping terminal 1120, further improving the uniform current flow of the test fixture 10.

[0069] In one optional embodiment of this application, the stacked cable superconducting conductor 120 includes multiple sets of parallel stepped stacked cables 1210, which are formed by bundling after being arranged in parallel.

[0070] The stepped stacked cable 1210 is a stepped composite conductor structure formed by stacking and rolling multiple superconducting conductors in layers. Its ends can be made into a stepped structure by controlling the length of different layers of strip. The stepped stacked cable 1210 achieves step-by-step engagement with the stepped protrusions 11210 through geometric matching, optimizing the current path and enhancing mechanical stability. Figure 9 The second schematic diagram shows the structure of the superconducting tape stack layer in the test fixture of a stacked cable superconducting conductor provided in an embodiment of this application: the stacked cable 1210 superconductor includes 3 sets of stacked cables 1210, each set of stacked cables 1210 includes 6 levels of superconducting conductors, and the ends are stepped.

[0071] For example, the stacked cable superconducting conductor 120 includes three sets of parallel stepped stacked cables 1210. Each set of stepped stacked cables 1210 is formed by cold pressing after stacking 6-level REBCO tape, with a single layer thickness of 0.2 mm and a width of 4 mm. The ends are processed into 6 steps, with each step height H = 0.2 mm. The three sets of stepped stacked cables 1210 are arranged in parallel and bound together with copper sleeves, with a width of 12 mm.

[0072] In this embodiment, the stacked cable superconducting conductor 120 is made by bundling multiple sets of stepped stacked cables 1210 in parallel arrangement. This parallel structure doubles the current carrying capacity of the stacked cable superconducting conductor 120, eliminates the edge current concentration effect, and makes the current distribution uniform.

[0073] In one optional embodiment of this application, any set of stacked cables 1210 includes vertically stacked multi-stage superconducting conductors, and the number of steps of the protrusions 11210 is the same as the number of steps of the multi-stage superconducting conductors.

[0074] The multi-level superconducting conductor consists of multiple superconducting tape units 1310 arranged vertically in a single stacked cable 1210. Each unit achieves independent electrical contact and mechanical support through a stepped structure. This hierarchical design ensures the independence of the current path for each conductor layer.

[0075] For example, when three sets of 6-level superconducting conductors are connected in parallel, each stacked cable 1210 consists of six layers of REBCO tape stacked together, with the ends machined into six steps, each step having a Δh=0.2mm. The stepped protrusions 11210 of the clamping terminal are correspondingly designed with six steps, each step having a Δh=0.2mm. The contact surface of each step is filled with indium tin alloy solder, with a filling thickness of 80μm. The clamping pressure is controlled at 12MPa, achieving a contact resistance ≤10^-10Ω·m². The three sets of stacked cables 1210 are connected in parallel and the entire structure is covered with an oxygen-free copper sleeve.

[0076] In this embodiment, by precisely matching the multi-stage superconducting conductors with the stepped protrusions 11210, a balanced current distribution among the parallel conductor groups is achieved, effectively solving the current concentration problem caused by differences in contact resistance. This structural design not only significantly improves the accuracy of test data but also enhances the mechanical stability of the overall structure through a graded pressure transmission mechanism.

[0077] In one optional embodiment of this application, the superconducting tape stack 130 includes horizontally stacked multi-level superconducting tapes 1310, which are parallel and oriented in the same direction.

[0078] The multi-level superconducting tape 1310 consists of multiple superconducting tape units 1310 stacked horizontally in the superconducting tape stacking layer 130, with each unit maintaining the same crystal orientation and tape extension direction. This structure forms a uniform equipotential surface through unidirectional alignment, ensuring a balanced current distribution across the horizontal cross-section. Figure 10 The second schematic diagram of the structure of a stacked cable superconducting conductor in a test fixture provided in an embodiment of this application is shown: the superconducting tape stack layer 130 includes horizontally stacked multi-level superconducting tapes 1310, which are parallel and oriented in the same direction, either to the left or to the right.

[0079] For example, 20 layers of REBCO strip are arranged horizontally in the same direction. The strip is 12mm wide and 80mm long. The layers are vacuum welded with indium tin alloy solder. The strip is embedded in the strip assembly groove 11220 of the clamping terminal 1120. The stacking direction of the strip is at an angle of 0° or 180° to the current injection direction, that is, arranged to the left or to the right.

[0080] In this embodiment, an isotropic equipotential conductor is constructed in the horizontal direction by stacking multi-level superconducting tapes 1310 in the same direction. When current is injected, the anisotropic resistance caused by the orientation difference is effectively suppressed, so that the current can be uniformly passed through the stacked cable superconducting conductor 120.

[0081] In one optional embodiment of this application, the clamping terminal 1120 is L-shaped, and the upper part of the L-shape of the clamping terminal 1120 is provided with a through hole 11230;

[0082] The through-hole 11230 is electrically connected to an external power cable, which supplies power to the superconducting conductor 120 of the stacked cable.

[0083] The L-shaped clamping terminal 1120 is a conductive clamping component with a vertically bent structure. Its cross-section is L-shaped, integrally formed from a horizontal L-shaped lower part and a vertical L-shaped upper part. This structure achieves the dual functions of multi-directional current conduction and mechanical support through a spatial bending design. The upper L-shaped part is a numerical extension of the L-shaped clamping terminal 1120, used to establish an external power connection and provide additional structural support. This area has a through-hole structure 11230 for cable fixing and current injection. Figure 11 The second schematic diagram of the structure of the clamping terminal in the test fixture of a stacked cable superconducting conductor provided in an embodiment of this application is shown: The L-shaped clamping terminal 1120 has a through hole 11230 on the upper part of the L-shape, a strip assembly groove 11220 on the upper surface of the lower part of the L-shape, and a protrusion 11210 on the lower surface.

[0084] The through-hole 11230 is an L-shaped circular channel structure that runs through the upper part, used to pass through power connection components and establish a low-resistance electrical connection. This structure ensures the reliability of high-current transmission through optimized aperture and surface treatment.

[0085] The external power cable is a high-current conductive cable assembly that connects the external power system to the test fixture 10. It features low thermal resistance and high mechanical strength.

[0086] For example, after an external power cable passes through the L-shaped upper through-hole 11230, it is locked with a nut. The contact surface between the external power cable and the through-hole 11230 is coated with conductive paste, which forms a low-resistance conductive layer after curing, capable of withstanding low temperature and high current density conditions. The external power cable is connected to a programmable DC power supply or a pulse current source (such as a 1000 A / 50 V power supply), and the current rise rate is adjustable (1~100 A / s) to adapt to the testing requirements of different superconducting conductors.

[0087] In this embodiment, the axial direct connection of the external power cable is achieved through the bending structure of the L-shaped clamping terminal 1120 and the design of the through hole 11230, thus avoiding the current deflection loss caused by the lateral connection of the external power cable.

[0088] In one optional embodiment of this application, the lower substrate 1110 and the clamping terminal 1120 are connected by a fastener 1130.

[0089] Fastener 1130 is a rigid connecting component used for mechanical connection and fixing clamping structure 110. It may be detachable or non-detachable and can provide stable clamping force and electrical contact pressure. Fastener 1130 includes, but is not limited to, bolts, pins, rivets, clamps, or quick-release locking mechanisms. For example, fastener 1130 is an internal hex bolt, used with a lock washer (such as a spring washer or a nylon locking washer).

[0090] Figure 12 This invention provides a schematic diagram of the fastener connection structure in a test fixture for a stacked cable superconducting conductor according to an embodiment of the present application:

[0091] The clamping terminal 1120 has a vertical through hole 11230, and the lower substrate 1110 also has a vertical through hole 11230. The clamping terminal 1120 and the lower substrate 1110 are rigidly connected by a fastener 1130, which is an internal hex bolt that passes through the vertical through hole 11230 of the clamping terminal 1120 and the vertical through hole 11230 of the lower substrate 1110. The fastener is locked with a nut, so that the end of the superconducting conductor 120 of the stacked cable is in contact with the protrusion 11210.

[0092] In this embodiment, the mechanical stability of the clamping structure 110 is ensured by the rigid connection and anti-loosening design of the fastener 1130.

[0093] In one optional embodiment of this application, the lower substrate 1110 and the clamping terminal 1120 are made of highly conductive materials, such as silver, copper, or a silver-copper alloy.

[0094] The high conductivity material is a metal or alloy material with low resistivity and high current carrying capacity. It can be silver, copper or silver-copper alloy, and is suitable for conductive components in the superconducting conductor test fixture 10 that require high current transmission.

[0095] For example, the lower substrate 1110 is made of oxygen-free copper, the clamping terminal 1120 is made of oxygen-free copper, and the contact surfaces of the lower substrate 1110 and the clamping terminal 1120 are polished and coated with conductive paste.

[0096] In this embodiment, by selecting highly conductive materials and optimizing the surface, the lower substrate 1110 and the clamping terminal 1120 achieve ultra-low contact resistance and current sharing characteristics, ensuring the stable conductivity of the test fixture 10 and significantly improving the accuracy of the test data.

[0097] In one optional embodiment of this application, the test fixture 10 for the stacked cable superconducting conductor 120 further includes an armor 140;

[0098] Armor 140 is made of high-strength, low-temperature resistant material, which is either stainless steel or copper alloy.

[0099] The armor 140 covers the center of the stacked cable superconducting conductor 120.

[0100] Armor 140 is a mechanical protection structure covering the center of the superconducting conductor 120 of the stacked cable, used to provide mechanical protection and thermal management.

[0101] High-strength, low-temperature resistant materials are those that maintain high mechanical strength and good toughness under low-temperature conditions, and can be stainless steel or copper alloys.

[0102] Figure 13 This application provides a schematic diagram of the armor structure in a test fixture for a stacked cable superconducting conductor according to an embodiment of the present application:

[0103] A pair of clamping structures 110 clamp the two ends of the stacked cable superconducting conductor 120 respectively, and the exposed center of the stacked cable superconducting conductor 120 is covered with armor 140.

[0104] In this embodiment, the high-strength, low-temperature resistant material and tight-coverage design of the armor 140 improve the mechanical stability and thermal management capability of the stacked cable superconducting conductor 120, and significantly enhance the reliability and testing accuracy of the test fixture 10 under extreme conditions.

[0105] Corresponding to at least one of the above embodiments, Figure 14 This paper presents a simulation diagram of the current distribution of a stacked cable superconducting conductor in a test fixture provided in an embodiment of this application:

[0106] By tightly fixing the end of the superconducting conductor 120 of the stacked cable within the clamping space formed by the positioning groove 11110 of the lower substrate 1110 and the protrusion 11210 of the clamping terminal 1120, and embedding the superconducting tape stack 130 in the tape assembly groove 11220 of the clamping terminal 1120, a composite conductive structure composed of the superconducting tape stack 130 and the clamping terminal 1120 is constructed. When current is injected from the clamping terminal 1120, an equipotential surface is first formed in the horizontal direction of the superconducting tape stack 130, so that the current is evenly distributed to the entire cross-section of the superconducting tape stack 130. Then the current is conducted vertically downward to the superconducting conductor 120 of the stacked cable. Since the contact resistance between the superconducting tape stack 130 and the clamping terminal 1120 is equalized through the action of the equipotential surface, the vertical resistance is consistent, so that the current can be synchronously and proportionally diverted to the superconducting conductor 120 of the stacked cable.

[0107] Corresponding to the aforementioned testing fixtures for stacked cable superconducting conductors, this application also provides an embodiment of a testing system for stacked cable superconducting conductors. Figure 15This is a schematic diagram of the structure of a test system for a stacked cable superconducting conductor according to an embodiment of this application. The test system 1 for the stacked cable superconducting conductor includes the test fixture 10 for the stacked cable superconducting conductor, a cryogenic container 20, and a data acquisition system 30.

[0108] The test fixture 10 is immersed in the cryogenic fluid in the cryogenic container 20, and the test fixture 10 is electrically connected to the data acquisition system 30.

[0109] The test system 1 for stacked cable superconducting conductors is an integrated test system for measuring the current-carrying performance of stacked cable superconducting conductors 120 in a cryogenic environment. It includes a test fixture 10, a cryogenic container 20, and a data acquisition system 30. The test system 1 for stacked cable superconducting conductors characterizes the current-carrying performance of stacked cable superconducting conductors 120 by precisely controlling the cryogenic environment and current loading.

[0110] The cryogenic container 20 is a sealed container that provides and maintains the cryogenic environment required for testing. It is filled with a cryogenic fluid (such as liquid nitrogen, liquid helium, etc.) to ensure that the superconducting conductor 120 of the stacked cable operates in a superconducting state. The cryogenic container 20 can be a Dewar flask with a double-layer vacuum insulation design. The inner liner can be made of stainless steel, and the outer wall can be made of aluminum alloy.

[0111] The data acquisition system 30 is an electronic measurement system used to monitor and record the electrical and thermal current-carrying performance parameters of the test fixture 10. It may include: a current source module: a programmable DC power supply (e.g., 1000 A / 50 V, accuracy ±0.05%FS), supporting pulse mode (rise time ≤1 ms); a voltage measurement unit: a nanovoltmeter (resolution 1 nV) combined with a multiplexer, sampling rate ≥1 kHz; and a data processing terminal: an embedded industrial computer running a custom LabVIEW program to achieve automatic data storage and analysis.

[0112] For example, the testing system 1 for the superconducting conductor of the stacked cable includes a Dewar flask, a cryogenic container containing liquid nitrogen, and the testing fixture 10 is completely immersed in the liquid nitrogen. Voltage signal points arranged in the testing fixture 10 are connected to the data acquisition system 30. The current is stepped up at a rate of 10 A / s, stabilizing for 30 seconds at each step, and the voltage-current (VI) curve is acquired synchronously until the superconducting conductor of the stacked cable is detected to have lost quench, thus obtaining the critical current, a current-carrying performance parameter.

[0113] In this embodiment, the precise testing of stacked cable superconducting conductors in a cryogenic environment is achieved through the coordinated operation of the testing fixture 10, the cryogenic container 20, and the data acquisition system 30. The optimized structural design of the testing fixture 10 ensures uniform current distribution and stable clamping, the cryogenic container 20 provides a stable superconducting working environment, and the data acquisition system 30 enables high-precision measurement of electrical parameters. This system can accurately reflect the current-carrying capacity of the stacked cable superconducting conductor, providing a reliable testing method for the engineering application of superconducting materials and significantly improving the accuracy and repeatability of the test data.

[0114] The above is a schematic scheme of a testing system for a stacked cable superconducting conductor according to an embodiment of this application. It should be noted that the technical solution of this testing system for a stacked cable superconducting conductor and the technical solution of the testing fixture for a stacked cable superconducting conductor belong to the same concept. For details not described in detail in the technical solution of the testing system for a stacked cable superconducting conductor, please refer to the description of the technical solution of the testing fixture for a stacked cable superconducting conductor.

[0115] Corresponding to the aforementioned testing system for stacked cable superconducting conductors, this application also provides embodiments of a testing method for stacked cable superconducting conductors. Figure 16 This is a flowchart illustrating a testing method for a stacked cable superconducting conductor according to an embodiment of this application. Figure 16 As shown, this method is applied to the testing system for the aforementioned stacked cable superconducting conductor, and includes the following specific steps:

[0116] Step 1602: Connect the external power cable to the clamping terminal 1120 through the L-shaped upper through hole of the clamping terminal 1120.

[0117] In step 1602, an electrical connection is used to allow current to pass through.

[0118] Step 1604: Place the two ends of the stacked cable superconducting conductor 120 into the positioning groove 11110 of the lower substrate 1110, clamp them by the cooperation of the protrusion 11210 of the clamping terminal 1120 with the positioning groove 11110, and use fasteners 1130 to fix and lock the lower substrate 1110 and the clamping terminal 1120.

[0119] In step 1604, the end of the stacked cable superconducting conductor 120 should be clamped between the positioning groove 11110 of the lower substrate 1110 and the protrusion 11210 of the clamping terminal 1120, and the stepped end structure of the stacked cable superconducting conductor 120 should correspond one-to-one with each step of the stepped protrusion 11210 of the clamping terminal 1120 to ensure that the entire end of the stacked cable superconducting conductor 120 is in complete and tight contact with the clamping structure of the test fixture 10, so as to achieve a uniform distribution of current on the cross section of the stacked cable superconducting conductor 120.

[0120] Step 1606: Place the assembled test fixture 10 into the cryogenic container 20.

[0121] In step 1606, there are no restrictions on the specific length of the stacked cable superconducting conductor 120.

[0122] Step 1608: Connect the pre-installed voltage signal line to the data acquisition system 30, and inject cryogenic fluid into the cryogenic container 20 until the stacked cable superconducting conductor 120 is completely submerged.

[0123] Step 1610: After the superconducting conductor 120 of the stacked cable reaches a stable superconducting state, a current-carrying capacity test is performed through the data acquisition system 30 to obtain the current-carrying capacity parameters of the superconducting conductor 120 of the stacked cable.

[0124] In this embodiment, the test fixture 10, through the precise fit of its stepped structure and the stable clamping of the fasteners 1130, ensures a uniform current distribution across the conductor cross-section; the cryogenic container 20 provides a stable superconducting working environment; and the data acquisition system 30 achieves high-precision acquisition of the conductor's electrical parameters. This test method can accurately reflect the current-carrying performance of the stacked cable superconducting conductor 120, providing a reliable testing method for the engineering application of superconducting materials. It realizes accurate performance testing of the stacked cable superconducting conductor 120 in a cryogenic environment, significantly improving the accuracy and repeatability of the test data. The entire testing process is simple to operate, applicable to stacked cable superconducting conductors of different lengths, and has good versatility and engineering applicability.

[0125] The above is an illustrative scheme of a testing method for a stacked cable superconducting conductor according to an embodiment of this application. It should be noted that the technical solution of this testing method for a stacked cable superconducting conductor and the technical solution of the testing fixture for the stacked cable superconducting conductor described above belong to the same concept. For details not described in detail in the technical solution of the testing method for the stacked cable superconducting conductor, please refer to the description of the technical solution of the testing fixture for the stacked cable superconducting conductor described above.

[0126] The foregoing has described specific embodiments of this application. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims may be performed in a different order than that shown in the embodiments and may still achieve the desired results. Furthermore, the processes depicted in the drawings do not necessarily require the specific or sequential order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0127] Those skilled in the art should also understand that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily essential to this application. In the above embodiments, the descriptions of each embodiment have different focuses, and for parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0128] The preferred embodiments disclosed above are merely illustrative of this application. The optional embodiments do not exhaustively describe all details, nor do they limit this application to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this application. These embodiments are selected and specifically described in this application to better explain the principles and practical applications of this application, thereby enabling those skilled in the art to better understand and utilize this application.

Claims

1. A testing fixture for stacked cable superconducting conductors, characterized in that, The system includes a clamping structure, a stacked cable superconducting conductor, and a superconducting tape stack layer. The clamping structure includes a lower substrate and clamping terminals. The width of the superconducting tape stack layer matches that of the stacked cable superconducting conductor, and the length of the superconducting tape stack layer matches that of the clamping terminals. The lower substrate has a positioning groove on its upper interface that matches the width of the superconducting conductor of the stacked cable. The clamping terminal has a protrusion on its lower interface that matches the width of the positioning groove, and a strip assembly groove on its upper surface. The positioning groove and the protrusion cooperate to clamp the end of the superconducting conductor of the stacked cable between the lower substrate and the clamping terminal, and the superconducting tape stack layer is embedded in the tape assembly groove.

2. The test fixture according to claim 1, characterized in that, The protrusion is stepped, and the end of the superconducting conductor of the stacked cable is stepped; The positioning groove and the stepped protrusion cooperate to clamp the stepped end of the stacked cable superconducting conductor step by step between the lower substrate and the clamping terminal.

3. The testing fixture according to claim 2, characterized in that, The stacked cable superconducting conductor comprises multiple sets of parallel stepped stacked cables, which are formed by arranging them in parallel and then binding them together.

4. The testing fixture according to claim 3, characterized in that, Any stacked cable group comprises vertically stacked multi-stage superconducting conductors, wherein the number of steps of the protrusions is the same as the number of steps of the multi-stage superconducting conductors.

5. The test fixture according to any one of claims 1-4, characterized in that, The superconducting tape stack layer comprises horizontally stacked multi-level superconducting tapes, which are parallel and oriented in the same direction.

6. The test fixture according to claim 1, characterized in that, The clamping terminal is L-shaped, and the upper part of the L-shape of the clamping terminal is provided with a through hole; The through hole is electrically connected to an external power cable, which supplies power to the superconducting conductor of the stacked cable.

7. The test fixture according to claim 1, characterized in that, The lower substrate and the clamping terminal are connected by fasteners.

8. The test fixture according to claim 1, characterized in that, The lower substrate and the clamping terminal are made of a highly conductive material, which is silver, copper, or a silver-copper alloy.

9. The test fixture according to claim 1, characterized in that, It also includes armor; The armor is made of a high-strength, low-temperature resistant material, which is stainless steel or copper alloy. The armor covers the central portion of the superconducting conductor of the stacked cable.

10. A testing system for stacked cable superconducting conductors, characterized in that, Includes the test fixture, cryogenic container, and data acquisition system for the stacked cable superconducting conductor as described in any one of claims 1-9; The test fixture is immersed in the cryogenic fluid in the cryogenic container, and the test fixture is electrically connected to the data acquisition system.

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