High-temperature superconducting electromagnetic vortex suppression structure for transient electromagnetic prospecting

Abstract

The application discloses a high-temperature superconducting electromagnetic eddy current suppression structure for transient electromagnetic detection and relates to the technical field of superconducting magnets. The two groups of metal flange rings are fixedly connected to the notch positions of the non-closed metal pipe, the polytetrafluoroethylene insulation gasket is clamped and installed between the two groups of metal flange rings, and the two groups of polytetrafluoroethylene insulation rings are assembled outside the metal flange rings. Through the arrangement of the application, the high-temperature superconducting electromagnetic eddy current suppression structure for transient electromagnetic detection is provided, the stainless steel outer pipe is arranged as a non-closed structure by using the polytetrafluoroethylene insulation flange structure, the conductive loop of the changing magnetic field induced eddy current is effectively cut off under the premise of retaining the metal structure, the liquid nitrogen temperature zone of the polytetrafluoroethylene material still maintains good flexibility and resilience, can be closely attached to the flange sealing surface at low temperature, and the integration of the sealing and insulation functions is realized.

Description

Technical Field

[0001] This invention relates to the field of superconducting magnet technology, and in particular to a high-temperature superconducting electromagnetic eddy current suppression structure for transient electromagnetic detection. Background Technology

[0002] In superconducting magnet systems, airborne transient electromagnetic detection equipment, and high-end material growth furnaces (such as single-crystal silicon growth furnaces), the support and shielding structures not only need to possess excellent mechanical strength and vacuum sealing performance, but also must cope with eddy current interference in complex electromagnetic environments. When a metallic conductor is placed in a changing magnetic field, a closed induced current, i.e., eddy current, is generated inside. This eddy current leads to energy loss, generates Joule heating, and forms a reverse magnetic field, severely interfering with the uniformity and stability of the main magnetic field, thereby affecting the detection accuracy of the equipment or the growth quality of the material.

[0003] Existing technology, such as the invention patent application number CN117854877A, discloses a superconducting magnet and cooling method for magnetron-controlled Czochralski single crystals. The specific method for suppressing eddy currents in this patent is as follows: a cylinder is circumferentially divided into multiple independent metal tiles (usually arc-shaped plates). Between adjacent metal tiles, each metal tile has a groove machined on its splicing side. When two tiles are joined, the two grooves form a transverse "T"-shaped channel. A T-shaped insulating strip made of epoxy resin-based fiber-reinforced composite material is embedded within this channel, thus splicing together a nearly closed cylindrical structure. This solution utilizes the T-shaped insulating partition to completely isolate adjacent metal tiles electrically, preventing the induced current from forming a closed loop circumferentially, thereby confining the eddy current within each independent metal tile and achieving the effect of suppressing eddy currents.

[0004] While existing technologies, such as the invention patent application CN117854877A, which discloses a method for suppressing eddy currents in a superconducting magnet and cooling method for magnetron-controlled Czochralski single crystals, can suppress the generation of eddy currents through physical separation, their structure has the following defects: 1. Poor mechanical integrity: The structure, which is spliced ​​from multiple tiles, has a lower overall rigidity and roundness retention than a single pipe. It is prone to deformation under vacuum negative pressure or external impact, which affects the stability of the magnet gap. 2. Low sealing reliability: There are splicing seams between each tile, resulting in a mesh-like distribution of sealing lines, forming a complex leakage network, making vacuum leak detection and maintenance difficult; 3. The assembly process is complicated, requiring extremely high machining accuracy and assembly time; 4. The T-type insulation material is made of epoxy resin-based fiber-reinforced composite material, which becomes brittle at low temperatures and is prone to cracking or delamination.

[0005] To address this issue, this invention designs a high-temperature superconducting electromagnetic eddy current suppression structure for transient electromagnetic detection. Utilizing a PTFE (polytetrafluoroethylene) insulating flange structure, the stainless steel outer tube is configured as a non-closed structure. While retaining the metal structure, this effectively cuts off the conductive circuit of eddy currents induced by the changing magnetic field. The PTFE material maintains good flexibility and resilience even at liquid nitrogen temperatures, allowing it to tightly adhere to the flange sealing surface at low temperatures, achieving integrated sealing and insulation functions. The overall structure is easy to disassemble, simple to assemble, and has low maintenance costs. Summary of the Invention

[0006] The purpose of this invention is to overcome the deficiencies in the existing technology and to propose a high-temperature superconducting electromagnetic eddy current suppression structure for transient electromagnetic detection.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A high-temperature superconducting electromagnetic eddy current suppression structure for transient electromagnetic detection includes two sets of polytetrafluoroethylene insulating rings, two sets of metal flange rings, and one set of polytetrafluoroethylene insulating gaskets. The first metal flange ring is fixedly connected to the notch at one end of the non-closed metal pipe, and the second metal flange ring is fixedly connected to the notch at the other end of the non-closed metal pipe. The polytetrafluoroethylene insulating gasket is clamped and installed between the opposite end faces of the first metal flange ring and the second metal flange ring. The first polytetrafluoroethylene (PTFE) insulating ring is assembled on the outside of the first metal flange ring, away from the second metal flange ring, and the second PTFE insulating ring is assembled on the outside of the second metal flange ring, away from the first metal flange ring.

[0008] Furthermore, it also includes fastening components, which include fastening screws, fastening nuts, and insulating tubes. The fastening screw passes sequentially through the assembly holes of the first PTFE insulating ring, the first metal flange ring, the PTFE insulating gasket, the second metal flange ring, and the second PTFE insulating ring. The through end of the fastening screw is threaded with a fastening nut. The insulating tube is sleeved on the screw section of the fastening screw and is located between the fastening screw and the assembly hole.

[0009] Furthermore, the non-closed metal tube is made of stainless steel, and the notch of the non-closed metal tube is a through groove structure opened along the axial direction of the tube body, with the notch penetrating both end faces of the non-closed metal tube.

[0010] Furthermore, the polytetrafluoroethylene (PTFE) insulating gasket has a ring structure, the cross-section of the PTFE insulating gasket is T-shaped, and an extension ring is formed on the outer side of the PTFE insulating gasket, which contacts the sidewalls of the first PTFE insulating ring and the second PTFE insulating ring respectively.

[0011] Furthermore, both the first and second PTFE insulating rings are annular sleeve structures. The inner ring dimensions of the two sets of PTFE insulating rings are respectively the assembly shaft diameter of the outer side of the corresponding side metal flange ring. The first PTFE insulating ring completely covers the exposed assembly area of ​​the outer side of the first metal flange ring, and the second PTFE insulating ring completely covers the exposed assembly area of ​​the outer side of the second metal flange ring.

[0012] Furthermore, the inner wall of the first polytetrafluoroethylene insulating ring abuts against the outer wall of the non-closed metal tube, and the inner wall of the second polytetrafluoroethylene insulating ring abuts against the outer wall of the non-closed metal tube. When the inner diameter of the first metal flange ring is smaller than the inner diameter of the second metal flange ring, the inner diameter of the PTFE insulating gasket is less than or equal to the inner diameter of the first metal flange ring; when the inner diameter of the first metal flange ring is larger than the inner diameter of the second metal flange ring, the inner diameter of the PTFE insulating gasket is less than or equal to the inner diameter of the second metal flange ring; when the inner diameter of the first metal flange ring is equal to the inner diameter of the second metal flange ring, the inner diameter of the PTFE insulating gasket is less than or equal to the inner diameter of the first metal flange ring.

[0013] Beneficial effects

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. Employing a non-closed stainless steel tube structure physically severs the induced eddy current conduction loop under a changing magnetic field. This significantly reduces Joule heating and additional interfering magnetic fields generated by eddy currents, preventing localized temperature rises from damaging the superconducting environment. It also eliminates the enormous thermal stress caused by mismatched coefficients of thermal expansion. Furthermore, it allows the tube to freely expand and contract during low-temperature and room-temperature cycling, preventing fretting wear and fatigue cracking. Compared to structures composed of multiple tile panels, it offers greater mechanical integrity.

[0015] 2. High sealing reliability: PTFE material maintains good flexibility and resilience even at liquid nitrogen temperatures (-196℃). When used as a gasket, it can tightly adhere to the flange sealing surface at low temperatures, effectively preventing internal liquid nitrogen leakage. Simultaneously, its extremely high volume resistivity eliminates the need for additional insulation components when the stainless steel tube is disconnected, achieving integrated "sealing" and "insulation" functions, simplifying the structure and improving system compactness.

[0016] 3. The assembly process is simple. This solution adopts a screw flange structure, which not only retains the high-strength fastening ability of metal screws and is not easily loosened due to vibration or thermal cycling, but also allows for disassembly, facilitating the replacement of gaskets or inspection of internal coils during field operations or repairs, thus reducing maintenance costs.

[0017] 4. Polytetrafluoroethylene (PTFE) material itself has a certain compressive strength and maintains good flexibility and resilience in the liquid nitrogen temperature range (-196℃). Attached Figure Description

[0018] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0019] Figure 1 This is a cross-sectional view of a high-temperature superconducting electromagnetic eddy current suppression structure for transient electromagnetic detection.

[0020] Figure 2 This is a diagram of a high-temperature superconducting electromagnetic eddy current suppression structure for transient electromagnetic detection.

[0021] In the diagram: First PTFE insulating ring--1, Second PTFE insulating ring--2, First metal flange ring--3, Second metal flange ring--4, Insulating tube--5, PTFE insulating gasket--6, Fastening component--7, Non-closed metal tube--8. Detailed Implementation

[0022] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0023] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0024] Reference Figure 1 -picture, A high-temperature superconducting electromagnetic eddy current suppression structure for transient electromagnetic detection includes two sets of polytetrafluoroethylene insulating rings, two sets of metal flange rings, and one set of polytetrafluoroethylene insulating gaskets. The first metal flange ring is fixedly connected to the notch at one end of the non-closed metal pipe, and the second metal flange ring is fixedly connected to the notch at the other end of the non-closed metal pipe. A polytetrafluoroethylene insulating gasket is clamped and installed between the opposite end faces of the first metal flange ring and the second metal flange ring; The first polytetrafluoroethylene (PTFE) insulating ring is assembled on the outside of the first metal flange ring, away from the second metal flange ring, and the second PTFE insulating ring is assembled on the outside of the second metal flange ring, away from the first metal flange ring.

[0025] In other preferred embodiments, fastening components are also included, comprising fastening screws, fastening nuts, and insulating tubes. The fastening screw passes through the assembly holes of the first PTFE insulating ring, the first metal flange ring, the PTFE insulating gasket, the second metal flange ring, and the second PTFE insulating ring in sequence. The through end of the fastening screw is threaded with a fastening nut. The insulating tube is sleeved on the screw section of the fastening screw and is located between the fastening screw and the assembly hole.

[0026] In other preferred embodiments, the non-closed metal tube is made of stainless steel, and the notch of the non-closed metal tube is a through groove structure opened along the axial direction of the tube body, with the notch penetrating both end faces of the non-closed metal tube.

[0027] In other preferred embodiments, the polytetrafluoroethylene (PTFE) insulating gasket has a ring structure, the cross-section of the PTFE insulating gasket is T-shaped, and an extension ring is formed on the outer side of the PTFE insulating gasket, which contacts the sidewalls of the first PTFE insulating ring and the second PTFE insulating ring respectively.

[0028] In other preferred embodiments, both the first PTFE insulating ring and the second PTFE insulating ring are annular sleeve structures. The inner ring dimensions of the two sets of PTFE insulating rings are respectively the assembly shaft diameter of the outer side of the corresponding side metal flange ring. The first PTFE insulating ring completely covers the exposed assembly area of ​​the outer side of the first metal flange ring, and the second PTFE insulating ring completely covers the exposed assembly area of ​​the outer side of the second metal flange ring.

[0029] In other preferred embodiments, the inner wall of the first polytetrafluoroethylene insulating ring abuts against the outer wall of the non-closed metal tube, and the inner wall of the second polytetrafluoroethylene insulating ring abuts against the outer wall of the non-closed metal tube. When the inner diameter of the first metal flange ring is smaller than the inner diameter of the second metal flange ring, the inner diameter of the PTFE insulating gasket is less than or equal to the inner diameter of the first metal flange ring; when the inner diameter of the first metal flange ring is larger than the inner diameter of the second metal flange ring, the inner diameter of the PTFE insulating gasket is less than or equal to the inner diameter of the second metal flange ring; when the inner diameter of the first metal flange ring is equal to the inner diameter of the second metal flange ring, the inner diameter of the PTFE insulating gasket is less than or equal to the inner diameter of the first metal flange ring.

[0030] In the specific plan: A high-temperature superconducting electromagnetic eddy current suppression structure for transient electromagnetic detection includes a first polytetrafluoroethylene (PTFE) insulating ring 1, a second PTFE insulating ring 2, a first metal flange ring 3, a second metal flange ring 4, an insulating tube 5, a PTFE insulating gasket 6, fastening components 7, and a non-closed metal tube 8.

[0031] The first metal flange ring 3 and the second metal flange ring 4 are respectively welded to the notches at both ends of a non-closed metal tube 8. By setting the stainless steel outer tube as a non-closed structure, the conductive circuit of the eddy current induced by the changing magnetic field is effectively cut off. The non-closed design allows the stainless steel outer tube to freely expand and contract when repeatedly cycling between a low temperature of 65K and room temperature, eliminating the huge thermal stress caused by the mismatch of thermal expansion coefficients.

[0032] A polytetrafluoroethylene (PTFE) insulating gasket 6 is installed between the first metal flange ring 3 and the second metal flange ring 4. The first PTFE insulating ring 1 and the second PTFE insulating ring 2 are respectively installed on the left side of the first metal flange ring 3 and the right side of the second metal flange ring 4. Utilizing its excellent insulation properties, the conductive continuity of the metal pipeline is physically cut off. PTFE material maintains good flexibility and resilience in the liquid nitrogen temperature range (-196℃). When used as a gasket, it can tightly fit the flange sealing surface at low temperatures, effectively preventing internal liquid nitrogen leakage. At the same time, it has extremely high volume resistivity, so no additional insulating components are needed when the metal pipe is disconnected. This achieves the integration of "sealing" and "insulation" functions, simplifies the structure, and improves the system's compactness.

[0033] Fastening component 7 generally includes screws, nuts, and washers. The screw shank is wrapped by insulating tube 5, which prevents the screw from becoming a "bridge" and reconnecting the stainless steel tubes on both sides. This ensures that the outer tube is "completely disconnected" in an electrical sense, thereby fundamentally suppressing the induced eddy currents generated in the pipeline by the changing magnetic field, eliminating the source of eddy current heating and parasitic magnetic fields, enabling reliable bolt flange connections, retaining the high-strength fastening capability of metal screws, and making them less prone to loosening due to vibration or thermal cycling. At the same time, the structure is detachable, facilitating the replacement of washers or inspection of internal coils during field operations or repairs, reducing maintenance costs.

[0034] The structure underwent strength testing at a frequency range of 20Hz to 25Hz and a voltage level of 2500V. The test results showed that its insulation structure can withstand the voltage stress within this range and meets safety standards.

[0035] The assembly method of the high-temperature superconducting electromagnetic eddy current suppression structure for transient electromagnetic detection is as follows: Step 1: Weld the first metal flange ring 3 and the second metal flange ring 4 to the notches at both ends of the non-closed metal tube 8. By setting the stainless steel outer tube as a non-closed structure, the conductive circuit of the eddy current induced by the changing magnetic field is effectively cut off. The non-closed design allows the stainless steel outer tube to freely expand and contract when repeatedly cycling between low temperature 65K and room temperature, eliminating the huge thermal stress caused by the mismatch of thermal expansion coefficients. Step 2: Install the PTFE insulating gasket 6 between the first metal flange ring 3 and the second metal flange ring 4. This ensures that the electrical continuity of the metal pipeline is physically cut off by utilizing its excellent insulation properties. PTFE material maintains good flexibility and resilience in the liquid nitrogen temperature range (-196℃). When used as a gasket, it can tightly adhere to the flange sealing surface at low temperatures, effectively preventing internal liquid nitrogen leakage. At the same time, it has extremely high volume resistivity. When the metal pipe is disconnected, no additional insulating components are required, realizing the integration of "sealing" and "insulation" functions, simplifying the structure and improving the system compactness. Step 3: Install the first PTFE insulating ring 1 and the second PTFE insulating ring 2 on the left side of the first metal flange ring 3 and the right side of the second metal flange ring 4 respectively to ensure the insulation of the entire flange structure and the sealing of the entire pipeline. Step 4: Install fastening component 7, which includes screws, nuts, and metal washers. First, fit the metal washer into the screw, then fit it into the insulating tube 5, insert it into the through hole of the flange structure, and install the metal washer and nut. Since the screw is wrapped by the insulating tube 5, it avoids the screw becoming a "bridge" and reconnecting the stainless steel tubes on both sides, ensuring that the outer tube is "completely disconnected" in an electrical sense. This fundamentally suppresses the induced eddy currents generated in the pipeline by the changing magnetic field, eliminates the source of eddy current heating and parasitic magnetic fields, and enables a reliable bolt flange connection. It retains the high-strength fastening ability of the metal screws and is not easy to loosen due to vibration or thermal cycling. At the same time, the structure is detachable, which is convenient for replacing the gasket or inspecting the internal coil during field operations or repairs, reducing maintenance costs.

[0036] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A high-temperature superconducting electromagnetic eddy current suppression structure for transient electromagnetic detection, characterized in that, It includes two sets of polytetrafluoroethylene insulating rings, two sets of metal flange rings, and one set of polytetrafluoroethylene insulating gaskets; The first metal flange ring is fixedly connected to the notch at one end of the non-closed metal pipe, and the second metal flange ring is fixedly connected to the notch at the other end of the non-closed metal pipe. The polytetrafluoroethylene insulating gasket is clamped and installed between the opposite end faces of the first metal flange ring and the second metal flange ring. The first polytetrafluoroethylene (PTFE) insulating ring is assembled on the outside of the first metal flange ring, away from the second metal flange ring, and the second PTFE insulating ring is assembled on the outside of the second metal flange ring, away from the first metal flange ring.

2. The high-temperature superconducting electromagnetic eddy current suppression structure for transient electromagnetic detection according to claim 1, characterized in that, It also includes fastening components, which include fastening screws, fastening nuts, and insulating tubes. The fastening screw passes sequentially through the assembly holes of the first PTFE insulating ring, the first metal flange ring, the PTFE insulating gasket, the second metal flange ring, and the second PTFE insulating ring. The through end of the fastening screw is threaded with a fastening nut. The insulating tube is sleeved on the screw section of the fastening screw and is located between the fastening screw and the assembly hole.

3. The high-temperature superconducting electromagnetic eddy current suppression structure for transient electromagnetic detection according to claim 1, characterized in that, The non-closed metal tube is made of stainless steel. The notch of the non-closed metal tube is a through groove structure opened along the axial direction of the tube body, and the notch penetrates through both end faces of the non-closed metal tube.

4. The high-temperature superconducting electromagnetic eddy current suppression structure for transient electromagnetic detection according to claim 1, characterized in that, The polytetrafluoroethylene (PTFE) insulating gasket has a ring structure and a T-shaped cross-section. An extension ring is formed on the outer side of the PTFE insulating gasket, and the extension ring contacts the sidewalls of the first and second PTFE insulating rings respectively.

5. The high-temperature superconducting electromagnetic eddy current suppression structure for transient electromagnetic detection according to claim 1, characterized in that, Both the first and second polytetrafluoroethylene (PTFE) insulating rings are annular sleeve structures. The inner ring dimensions of the two sets of PTFE insulating rings are respectively the assembly shaft diameter of the outer side of the corresponding side metal flange ring. The first PTFE insulating ring completely covers the exposed assembly area of ​​the outer side of the first metal flange ring, and the second PTFE insulating ring completely covers the exposed assembly area of ​​the outer side of the second metal flange ring.

6. The high-temperature superconducting electromagnetic eddy current suppression structure for transient electromagnetic detection according to claim 1, characterized in that, The inner wall of the first polytetrafluoroethylene insulating ring abuts against the outer wall of the non-closed metal tube, and the inner wall of the second polytetrafluoroethylene insulating ring abuts against the outer wall of the non-closed metal tube. When the inner diameter of the first metal flange ring is smaller than the inner diameter of the second metal flange ring, the inner diameter of the PTFE insulating gasket is less than or equal to the inner diameter of the first metal flange ring; when the inner diameter of the first metal flange ring is larger than the inner diameter of the second metal flange ring, the inner diameter of the PTFE insulating gasket is less than or equal to the inner diameter of the second metal flange ring; when the inner diameter of the first metal flange ring is equal to the inner diameter of the second metal flange ring, the inner diameter of the PTFE insulating gasket is less than or equal to the inner diameter of the first metal flange ring.

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