Electromagnetic signal superconducting observation system based on micro-shielding and thermal management and design method

Abstract

The invention discloses an electromagnetic signal superconducting observation system based on micro-shielding and thermal management and a design method, and the system comprises a high-temperature sensor unit which comprises a pressure-resistant constant-temperature container, a specially-made non-magnetic glass Dewar flask disposed in the pressure-resistant constant-temperature container, and a built-in three-axis high-temperature superconducting sensor. The pressure-resistant constant-temperature container comprises a base body made of carbon fiber reinforced plastics, and a low-frequency frequency-selecting shielding layer, an insulating thin layer, an absorbing layer and a high-frequency shielding layer are sequentially arranged outside the base body. According to the invention, the interference of high-frequency noise in a complex environment and the thermal noise of the three-axis high-temperature superconducting sensor can be significantly reduced. According to the system provided by the invention, the low-noise electromagnetic signal detection of the high-temperature superconducting sensor can be realized in a complex environment, the application range of electromagnetic method technology resource exploration can be widened, and the detection precision can be improved.

Description

Technical Field

[0001] This application belongs to geophysical exploration technology, involving low-noise observation technology of electromagnetic signals, and specifically relates to an electromagnetic signal superconducting observation system and design method based on micro-shielding and thermal management. Background Art

[0002] Time-domain electromagnetic method (TDEM), also known as transient electromagnetic method (TEM), is a type of artificial source electromagnetic method. It primarily targets the conductivity of underground media and, therefore, offers unique advantages in detecting good conductors such as metallic ore bodies. However, the accuracy and reliability of traditional coil-based electromagnetic detection methods are often compromised by complex environments and high background noise. High-sensitivity electromagnetic detection technology can provide greater accuracy and reliability under complex conditions, and its development is therefore crucial for observing deeper and more precise secondary field signals in these environments.

[0003] Superconducting quantum interference devices (SQUIDs), as highly sensitive magnetic field sensors, are widely used in fields such as medical imaging and geological exploration. With sensitivities reaching 10⁻⁵ to 10⁻⁶ nT, SQUIDs can accurately detect minute magnetic field variations within the human body, even if these variations are as small as one billionth of the Earth's magnetic field strength. Currently, domestic high-temperature SQUIDs have been successfully applied to biomagnetic measurements and terrestrial magnetic exploration.

[0004] Although high-temperature SQUID technology has significant advantages, its application in complex environments still faces a number of technical challenges. First, the flux-to-voltage conversion characteristics of the SQUID are periodically nonlinear and require linear conversion through a dedicated low-noise digital readout circuit 9, which places high demands on circuit design. Secondly, in order to achieve observation in complex high-temperature or high-pressure environments, it is also necessary to design effective temperature-resistant and pressure-resistant containers to protect the safety of the equipment. Complex environments often have complex electromagnetic waves, which can cause relatively large noise interference. Therefore, how to design efficient magnetic shielding and noise reduction technology to ensure signal accuracy is the key to technological breakthroughs. In addition, the SQUID detection system may also face problems such as high-pressure environment, pressure imbalance inside and outside the cabin after liquid nitrogen volatilization, and susceptibility of equipment to water erosion when working for a long period of time in a complex environment. Summary of the Invention

[0005] In order to solve the above technical problems, the present application provides an electromagnetic signal superconducting observation system based on micro-shielding and thermal management, which solves the problem of insufficient magnetic signal measurement accuracy under long-term high-precision and long-period detection in complex background magnetic fields.

[0006] The present application also provides a design method for an electromagnetic signal superconducting observation system based on micro-shielding and thermal management.

[0007] This application adopts the following technical solutions: The first aspect of the present application provides an electromagnetic signal superconducting observation system based on micro-shielding and thermal management, comprising: The high-temperature sensor unit includes a pressure-resistant constant-temperature container, a non-magnetic glass Dewar flask placed in the pressure-resistant constant-temperature container, and a three-axis high-temperature superconducting sensor is arranged in the non-magnetic glass Dewar flask. The pressure-resistant constant-temperature container includes a base body made of carbon fiber reinforced plastic, and a low-frequency selective shielding layer, an insulating thin layer, an absorption layer and a high-frequency shielding layer are sequentially arranged outside the base body.

[0008] Furthermore, the shielding effectiveness curves of different materials in different layers of the pressure-resistant constant temperature container are calculated, the shielding material and thickness of each layer are determined, the shielding effectiveness curves of each layer are summed to obtain the total shielding effectiveness curve, and the total shielding effectiveness within the target frequency range in the total shielding effectiveness curve of the selected shielding material and thickness meets the minimum total shielding effectiveness required by the design.

[0009] Furthermore, the high-frequency shielding layer is configured as a metal grid structure.

[0010] Furthermore, the absorption layer is made of conductive rubber or radio frequency absorbing foam.

[0011] Furthermore, the non-magnetic glass Dewar flask is filled with liquid nitrogen, a three-axis high-temperature superconducting sensor is fixed at one end of a polyetheretherketone probe, the three-axis high-temperature superconducting sensor is connected to the low-temperature twisted-pair phosphor copper wire in the polyetheretherketone probe, the other end of the polyetheretherketone probe extends out of the bottle mouth of the non-magnetic glass Dewar flask, the bottle mouth is sealed by an insulating insulator, the polyetheretherketone probe is connected to the collection circuit through the low-temperature twisted-pair phosphor copper wire, the output end of the collection circuit extends out of the pressure-resistant constant temperature container through a multi-core waterproof cable connector, and the collected electromagnetic signal is transmitted to the collection station via the transmission cable.

[0012] Furthermore, the non-magnetic glass Dewar flask includes two glass layers, a vacuum insulation layer is provided between the two glass layers, a silver-plated layer is provided on the outer side of the inner glass layer, and a blue aluminum coating is provided on the outer side of the outer glass layer.

[0013] Furthermore, the parameters of the non-magnetic glass Dewar flask, the polyetheretherketone probe, and the low-temperature twisted-pair phosphorus copper wire satisfy the expression equation of the liquid nitrogen level change and the thermal conductivity and size of the material: ,in, is the temperature change of liquid nitrogen, is the cross-sectional area of ​​the non-magnetic glass Dewar flask, is the heat of vaporization of liquid nitrogen, is the density of liquid nitrogen, is the liquid level change of liquid nitrogen, is the total heat inflow; The total heat influx: ,in, is the thermal radiation of the glass layer, is the heat radiation of the silver plating layer, is the heat conduction of liquid nitrogen, It is the radiant heat of the insulating body; The heat radiation of the inner glass layer and the silver coating is: ,in, is room temperature, is the liquid nitrogen level, is the height of the vacuum insulation layer, is the thermal conductivity of glass, is the cross-sectional area of ​​the glass, is the thermal conductivity of silver plating, is the silver-plated cross-sectional area; ,in, is the total heat conduction, is the thermal conductivity of liquid nitrogen, is the length of the PEEK probe in the non-magnetic glass Dewar flask, is the thermal conductivity of the PEEK probe, is the thermal conductivity of low-temperature twisted-pair phosphor copper wire; Thermal radiation from insulating materials: ,in, is the Stefan-Boltzmann constant, is the efficiency coefficient, is liquid nitrogen temperature.

[0014] A second aspect of the present application provides a design method for an electromagnetic signal superconducting observation system based on micro-shielding and thermal management, comprising: The frequency band to be shielded is selected according to the signal to be detected, and the outer layer of the pressure-resistant constant temperature container is set as a low-frequency selective shielding layer, an absorption layer and a high-frequency shielding layer according to the frequency band to be shielded; Calculate the shielding effectiveness curves of different materials for different layers of the pressure-resistant constant temperature container, determine the shielding material and thickness of each layer, sum the shielding effectiveness curves of each layer to obtain the total shielding effectiveness curve, and make the total shielding effectiveness within the target frequency range of the total shielding effectiveness curve of the selected shielding material and thickness meet the minimum total shielding effectiveness required by the design. Further, it also includes: Establishing a heat transfer model including thermal conductivity and dimensions of materials, the heat transfer model including a non-magnetic glass Dewar flask, a polyetheretherketone probe, and a low-temperature twisted-pair phosphor copper wire; Calculate the total heat influx; According to the law of conservation of heat, the total heat inflow and the heat of vaporization and density of liquid nitrogen are used to obtain the expression equation of the liquid nitrogen level change and the thermal conductivity and size of the material; Based on the working time and size restrictions, the parameters of the non-magnetic glass Dewar flask, polyetheretherketone probe and low-temperature twisted-pair phosphor copper wire are confirmed using an expression equation that combines the liquid nitrogen level change with the thermal conductivity and size of the material.

[0015] Furthermore, the expression equation for the change in liquid nitrogen level and the thermal conductivity and size of the material is: , in, is the temperature change of liquid nitrogen, is the cross-sectional area of ​​the non-magnetic glass Dewar flask, is the heat of vaporization of liquid nitrogen, is the density of liquid nitrogen, is the liquid level change of liquid nitrogen, is the total heat inflow; The total heat inflow is: ,in, is the thermal radiation of the glass layer, is the heat radiation of the silver plating layer, is the heat conduction of liquid nitrogen, It is the radiant heat of the insulating body; The heat radiation of the inner glass and silver coating is: ,in, is room temperature, is the liquid nitrogen level, is the height of the vacuum insulation layer, is the thermal conductivity of glass, is the cross-sectional area of ​​the glass, is the thermal conductivity of silver plating, is the silver-plated cross-sectional area; , is the total heat conduction, is the thermal conductivity of liquid nitrogen, is the length of the PEEK probe in the non-magnetic glass Dewar flask, is the thermal conductivity of the PEEK probe, is the thermal conductivity of low-temperature twisted-pair phosphor copper wire; Thermal radiation from insulating materials: ,in, is the Stefan-Boltzmann constant, is the efficiency coefficient, is liquid nitrogen temperature.

[0016] Compared to existing systems, the technical solutions of the various embodiments of this application offer the following advantages: They can significantly reduce high-frequency noise interference in complex environments and reduce the thermal noise of tri-axis high-temperature superconducting sensors. The system provided by this application enables low-noise electromagnetic signal detection from high-temperature superconducting sensors in complex environments, helping to broaden the application scope of electromagnetic resource exploration and improve detection accuracy.

[0017] Compared to existing systems, the high-temperature superconductor-based electromagnetic signal detection system provided by this application offers the following benefits: By designing a pressure-resistant, thermostatic container with micro-shielding performance, this application significantly reduces high-frequency noise interference in complex environments. Furthermore, by modeling and analyzing liquid nitrogen containers using thermal management technology, a highly insulating, non-magnetic glass Dewar flask was designed, reducing the thermal noise of the triaxial high-temperature superconducting sensor. This system, enabled by this application, enables low-noise electromagnetic signal detection using triaxial high-temperature superconducting sensors in complex environments, helping to broaden the application scope of electromagnetic resource exploration and improve detection accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagram of the overall structure of the electromagnetic signal superconducting observation system based on micro-shielding and thermal management provided in an embodiment of the present application; Figure 2 This is a schematic diagram of the legal structure of a four-corner bracket provided in an embodiment of the present application; Figure 3 is a cross-sectional view of a transmission cable provided in an embodiment of the present application; Figure 4 This is a structural view of the non-magnetic glass Dewar flask provided in an embodiment of the present application. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0020] The superconducting observation system uses a superconducting quantum interference device (SQUID) as a magnetic field detection sensor to collect electromagnetic signals. Multiple magnetic field detection sensors can be set up in a superconducting observation system. Figure 1The overall structural diagram of the electromagnetic signal superconducting observation system based on micro-shielding and thermal management is shown. The electromagnetic signal superconducting observation system based on micro-shielding and thermal management provided in the embodiment of the present application includes a high-temperature sensor unit, a control and data acquisition unit, and a transmission unit. The high-temperature sensor unit used in the present application includes a pressure-resistant constant-temperature container 13, a non-magnetic glass Dewar flask 7 placed in the pressure-resistant constant-temperature container 13, and a three-axis high-temperature superconducting sensor 5 is arranged in the non-magnetic glass Dewar flask 7, wherein the pressure-resistant constant-temperature container 13 includes a base body made of carbon fiber reinforced plastic, and a low-frequency selective shielding layer, an insulating thin layer, an absorption layer and a high-frequency shielding layer are sequentially arranged outside the base body.

[0021] The pressure-resistant constant-temperature container 13 can be fixed by a four-corner bracket; the non-magnetic glass Dewar flask 7 in the pressure-resistant constant-temperature container 13 is filled with liquid nitrogen, the three-axis high-temperature superconducting sensor 5 is fixed to one end of a polyetheretherketone probe 8, the three-axis high-temperature superconducting sensor 5 is connected to the low-temperature twisted-pair phosphor copper wire 6 in the polyetheretherketone probe 8, the other end of the polyetheretherketone probe 8 extends out of the bottle mouth of the non-magnetic glass Dewar flask 7, the bottle mouth is sealed by an insulating insulator, the polyetheretherketone probe 8 is connected to the collection circuit through the low-temperature twisted-pair phosphor copper wire 6, the output end of the collection circuit extends out of the pressure-resistant constant-temperature container 13 through a multi-core waterproof cable connector 14, and transmits the collected electromagnetic signal to the collection station 3 via the transmission cable 15, and the collection station 3 communicates with the remote control center through the wireless communication system 4.

[0022] In one embodiment, the pressure-resistant constant-temperature container 13 is made of carbon fiber reinforced plastic, which has excellent pressure and temperature resistance, ensuring the safety of electronic equipment inside the pressure-resistant constant-temperature container 13 in complex environments. The pressure-resistant constant-temperature container 13 is an elongated cylindrical container formed in one piece, and has good airtightness and waterproof properties. A multi-core waterproof cable connector 14 is installed on the top of the pressure-resistant constant-temperature container 13, which can be connected to the transmission cable 15. Figure 1 Combine Figure 4 As shown, Figure 4 This is a structural diagram of a non-magnetic glass Dewar flask. The non-magnetic glass Dewar flask 7 comprises an inner glass layer 71 and an outer glass layer 73. A vacuum insulation layer 72 is placed between the glass layers. The outer surface of the inner glass layer 71 is coated with a silver layer 74, while the outer surface of the outer glass layer 73 is coated with a blue aluminum coating 75. This serves to isolate radiative heat transfer and reduce the evaporation rate of the liquid nitrogen inside, thereby maintaining the operating temperature of the triaxial high-temperature superconducting sensor 5. A platinum resistance temperature sensor is also placed inside the non-magnetic glass Dewar flask 7 to monitor the operating temperature in real time.

[0023] See also Figure 1As shown, the three-axis high-temperature superconducting sensor 5 is a three-piece high-temperature superconducting quantum interference device that measures magnetic field signals in the three directions of X, Y, and Z respectively. The three-axis high-temperature superconducting sensor 5 is fixed on a polyetheretherketone probe 8 at the bottom of a non-magnetic glass Dewar flask 7 and is completely immersed in liquid nitrogen. The non-magnetic glass Dewar flask 7 is connected to the acquisition circuit using a low-temperature twisted-pair phosphor copper wire 6 to reduce heat conduction while transmitting electrical signals.

[0024] The acquisition circuit is located outside the non-magnetic glass Dewar flask 7, but still inside the pressure-resistant constant temperature container 13. The acquisition circuit includes: The readout circuit 9, readout circuit controller 10, nickel-metal hydride battery 12 and photoelectric converter 11 are fixed inside the pressure-resistant constant temperature container 13 via a keel. The output signal of the readout circuit 9 is the input signal of the three-axis high-temperature superconducting sensor 5. The output parameters of the readout circuit 9 can be adjusted according to the readout circuit controller 10, thereby adjusting the working state of the three-axis high-temperature superconducting sensor 5. The readout circuit 9 is also responsible for amplifying, demodulating and collecting the output signal of the three-axis high-temperature superconducting sensor 5 for transmission. Each sensor on each axis of the three-axis high-temperature superconducting sensor 5 uses a readout circuit 9.

[0025] The readout circuit controller 10 is the core of the sensing system. It can automatically adjust the output parameters of the readout circuit 9, so that the three-axis high-temperature superconducting sensor 5 can operate at the optimal operating point with long period and low noise and output signals. The readout circuit controller 10 can also analyze the remote control signal sent by the sea surface and adjust the output parameters of the readout circuit 9 according to the control signal, realizing a manual remote adjustment system.

[0026] The photoelectric converter 11 converts the electric signal output from the readout circuit 9 into an optical signal, and converts the optical signal into an electric signal.

[0027] The battery 12 is a large-capacity nickel-metal hydride dry cell, which can provide energy for the system for a long period in a complex environment.

[0028] The keel plays a fixing role inside the pressure-resistant constant temperature container 13 and is made of polyethylene material. Its size is customized according to the inner diameter of the pressure-resistant constant temperature container 13 and the outer dimensions of the internal components to ensure relative stability between the internal components and the pressure-resistant constant temperature container 13.

[0029] The control and data acquisition unit includes a collection station 3 and a remote control center 2. The remote control center 2 is located near the transmitting source 1 and can control the transmitting source 1 and send and receive data from the collection station 3. It has a human interaction function, which can view data in real time, check the operating status of the equipment, and control the working status of the three-axis high-temperature superconducting sensor 5. The collection station 3 is made of polyethylene and is slightly away from the triaxial high-temperature superconducting sensor 5, serving as a signal relay and rapid positioning device. The collection station 3 has a built-in transmission module that enables long-distance communication with the remote control center 2. The built-in solar energy storage module collects solar energy on the ground to store electricity, which can be supplied to the high-temperature sensor unit via the transmission unit during long-term detection. The transmission unit uses a composite armored transmission cable 15, which is responsible for signal transmission, air pressure release and power transmission. Figure 3 As shown, the exterior of the transmission cable 15 comprises three layers of material in sequence: a wear-resistant layer 21, a waterproof layer 22, and a shielding layer 23. The wear-resistant layer 21 is made of polypropylene rope and coated with asphalt to resist seawater erosion, abrasion, and external physical damage. The waterproof layer 22 is a water-blocking tape that prevents moisture from penetrating and diffusing axially when the transmission cable 15 is damaged. The shielding layer 23 is made of a semi-conductive material to uniformly distribute the electric field and extend the insulation life. There are four types of pipes inside the transmission cable 15: a nitrogen release pipe 18, a single-mode multi-core coaxial optical fiber 24, a power copper wire 20 and an emergency drain pipe 19; there are three nitrogen release pipes 18, which are made of nylon and are used to release volatile liquid nitrogen to maintain system pressure stability; the single-mode multi-core coaxial optical fiber 24 transmits data and control signals using optical signals, effectively avoiding the impact of high-frequency electromagnetic interference signals on the system; the emergency exhaust pipe 19 can realize the emergency release of liquid nitrogen in an emergency situation to avoid further damage to the equipment; the single-core power copper wire 20 can replenish energy for the submarine high-temperature sensing unit to realize power transmission; in addition, the transmission cable 15 is also filled with a waterproof filler 25, which makes the interior of the transmission cable 15 tighter and further enhances the waterproofness of the transmission cable 15. The multi-core waterproof cable connector 14 also includes four interfaces for connecting to four pipes within the transmission cable 15, such as a nitrogen release interface, a single-mode multi-core coaxial fiber interface, a power copper wire interface, and an emergency drainage pipe interface. The nitrogen release interface is connected to the non-magnetic glass Dewar flask 7 through a pipeline and an insulating body; the power copper wire interface is used to connect to the power supply circuit; the single-mode multi-core coaxial fiber 24 is connected to the readout circuit controller 10 through the single-mode multi-core coaxial fiber interface; and the emergency drainage pipe is connected to the non-magnetic glass Dewar flask 7 through an emergency drainage pipe connector, a set pipeline, and an insulating body. It is opened only in an emergency to discharge liquid nitrogen. It is understandable that a control valve is provided to control the opening and closing of the pipeline.

[0030] In one embodiment, micro-shielding technology is used to reduce the impact of environmental noise on the observation system. Micro-shielding technology uses specific composite shielding materials and layered shielding technology to perform frequency-selective shielding on the periphery of the magnetic field detection sensor, effectively shielding signals in the frequency band above GHz while allowing signals in the kHz band to penetrate, thereby reducing environmental radio frequency electromagnetic interference while reducing the impact on the signal to be observed. To address the problem that high-frequency signals will cause instability of the three-axis high-temperature superconducting sensor 5, the pressure-resistant and temperature-resistant container 13 can be designed with carbon fiber reinforced plastic as the base body, taking into account the pressure resistance, temperature resistance and electromagnetic shielding requirements. This can shield high-frequency signals while ensuring the safety of electronic equipment in complex environments. Taking into account the micro-shielding requirements, a two-layer composite shielding method is used for shielding. That is, the outermost high-frequency shielding layer uses high-conductivity copper as the shielding material to absorb interference in the high-frequency band above GHz. The middle absorption layer can be made of radio frequency absorbing foam. The innermost low-frequency selective shielding layer uses a high-permeability material to allow low-frequency signals to pass.

[0031] Calculate the shielding effectiveness curves of different materials in different layers of the pressure-resistant constant temperature container 13, determine the shielding material and thickness of each layer, sum the shielding effectiveness curves of each layer to obtain the total shielding effectiveness curve, and make the total shielding effectiveness within the target frequency range in the total shielding effectiveness curve of the selected shielding material and thickness meet the minimum total shielding effectiveness required by the design.

[0032] The specific design process includes: The frequency band required for shielding is selected based on the signal to be detected. Generally speaking, the frequency band required for time domain electromagnetic method signals is below 100kHz, and the frequency band required for magnetic method signals is below 2kHz. The number of layers is selected based on the frequency band, generally three layers, namely high-frequency shielding layer, absorption layer and low-frequency selective shielding layer. The high-frequency shielding layer is generally made of high-conductivity material to effectively shield signals above GHz. The absorption layer is made of RF absorbing foam to attenuate high-frequency signals, and a thin insulating layer is covered between the absorption layer and the low-frequency selective shielding layer to suppress the formation of eddy currents between the layers. The low-frequency selective shielding layer is made of a material that effectively shields the MHz~GHz frequency band, but penetrates kHz signals. Calculate the shielding effectiveness curves of different layers and materials according to the shielding effectiveness formula, and then determine the shielding material and thickness of each layer; The shielding effectiveness formula is: , is a frequency-dependent shielding effectiveness curve; where is the reflection loss, which can be ignored at high efficiency loss; is the reflection loss, which is calculated as follows: ; is the absorption loss, and its calculation formula is: , in is the frequency, is the thickness of the shielding material, is the relative magnetic permeability, is the conductivity; The overall shielding effectiveness curve is: is the total shielding effectiveness curve, For the Layer shielding effectiveness curve; The total shielding effectiveness within the target frequency range in the total shielding effectiveness curve meets the minimum total shielding effectiveness required by the design, which is used to determine whether the designed shielding materials and thicknesses of each layer meet the requirements.

[0033] Furthermore, in order to reduce the impact of eddy currents caused by the high-frequency shielding layer on observation, the outermost high-frequency shielding layer should be in the form of a metal grid or a thin metal foil mesh to block the annular eddy current path to the greatest extent.

[0034] Shielding effectiveness calibration is performed based on the selected materials to verify the rationality of the design. The calibration method is based on the existing calibrated shielding effectiveness test method. After setting the frequency sweep, the total shielding effectiveness curve is obtained based on the response to determine whether the design requirements are met.

[0035] In one embodiment, the high-frequency shielding layer uses a copper mesh with a thickness of 0.025 mm and is cut and partitioned with an interval of approximately 0.001 mm, achieving a shielding effectiveness of more than 60 dB for high-frequency signals.

[0036] The absorption layer uses 0.01mm insulating plastic film to separate the inside and outside and reduce eddy currents.

[0037] The low-frequency selective shielding layer is made of low-conductivity plastic with a thickness of 0.01mm, which can achieve low-frequency shielding and penetration of the required frequency band.

[0038] In one embodiment, see Figure 1 Combine Figure 4As shown, the designed non-magnetic glass Dewar flask 7 achieves constant temperature control and reduces liquid nitrogen thermal noise. The non-magnetic glass Dewar flask 7 is filled with liquid nitrogen, and a triaxial high-temperature superconducting sensor 5 is fixed to one end of a polyetheretherketone (PEEK) probe 8. The triaxial high-temperature superconducting sensor 5 is connected to a low-temperature twisted-pair phosphorus copper wire 6 within the PEEK probe 8. The other end of the PEEK probe 8 extends beyond the mouth of the non-magnetic glass Dewar flask 7, which is sealed with an insulating material. The PEEK probe 8 is connected to the data acquisition circuit via the low-temperature twisted-pair phosphorus copper wire 6. The output end of the data acquisition circuit extends out of the pressure-resistant constant-temperature container 13 via a multi-core waterproof cable connector 14, and the collected electromagnetic signals are transmitted to the data acquisition station 3 via a transmission cable 15. The non-magnetic glass Dewar flask 7 comprises an inner glass layer 71 and an outer glass layer 73, with a vacuum insulation layer 72 between the two glass layers. The outer surface of the inner glass layer 71 is provided with a silver coating 74, and the outer surface of the outer glass layer 73 is provided with a blue aluminum coating 75.

[0039] The parameters of the non-magnetic glass Dewar flask 7, the polyetheretherketone probe 8, and the low-temperature twisted-pair phosphorus copper wire 6 satisfy the expression equation of the liquid nitrogen level change and the thermal conductivity and size of the material: , in, is the temperature change of liquid nitrogen, is the cross-sectional area of ​​the non-magnetic glass Dewar flask, is the heat of vaporization of liquid nitrogen, is the density of liquid nitrogen, is the liquid level change of liquid nitrogen, is the total heat inflow; , in is the thermal radiation of the glass layer, is the heat radiation of the silver plating layer, is the heat conduction of liquid nitrogen, It is the radiant heat of the insulating body; The heat radiation of the inner glass and silver coating is: , in, is room temperature, is the liquid nitrogen level, is the height of the vacuum insulation layer, is the thermal conductivity of glass, is the cross-sectional area of ​​the glass, is the thermal conductivity of silver plating, is the silver-plated cross-sectional area; , is the total heat conduction, is the thermal conductivity of liquid nitrogen, is the length of the PEEK probe in the non-magnetic glass Dewar flask, is the thermal conductivity of the PEEK probe, is the thermal conductivity of low-temperature twisted-pair phosphor copper wire; Thermal radiation from insulating materials: ,in is the Stefan-Boltzmann constant, is the efficiency coefficient, is liquid nitrogen temperature.

[0040] The embodiments of the present application address high-frequency environmental noise by using micro-shielding technology to electromagnetically shield the device container and internal circuits in specific frequency bands, ensuring that the desired observation signal is not distorted while reducing the impact of environmental noise on the observation system. To address the serious problem of heat loss in the non-magnetic glass Dewar flask, a low-thermal-conductivity thermal management technology is used to reduce heat conduction in the insulation system, thereby reducing the thermal noise of the three-axis high-temperature superconducting sensor caused by temperature rise. To address the problem of excessive electronic noise caused by the difficulty of heat dissipation in the readout circuit, a high-thermal-conductivity thermal management technology is used to improve the heat transfer efficiency of the readout circuit, reduce the readout circuit noise, and achieve low-noise signal output, amplification, demodulation, and acquisition. This achieves low-noise observation of electromagnetic signals from the three-axis high-temperature superconducting sensor in complex environments, which will facilitate electromagnetic resource exploration.

[0041] The embodiment of the present application also provides a design method for an electromagnetic signal superconducting observation system based on micro-shielding and thermal management, comprising: selecting a frequency band to be shielded according to the signal to be detected, and setting the outer layer of the pressure-resistant constant temperature container 13 as a low-frequency selective shielding layer, an absorption layer, and a high-frequency shielding layer according to the frequency band to be shielded; Calculate the shielding effectiveness curves of different materials in different layers of the pressure-resistant constant temperature container 13, determine the shielding material and thickness of each layer, sum the shielding effectiveness curves of each layer to obtain the total shielding effectiveness curve, and make the total shielding effectiveness within the target frequency range in the total shielding effectiveness curve of the selected shielding material and thickness meet the minimum total shielding effectiveness required by the design.

[0042] In one embodiment, the non-magnetic glass Dewar flask 7 and its internal structure are designed according to thermal management technology, and a heat transfer model including the thermal conductivity and size of the material is established. The heat transfer model includes the non-magnetic glass Dewar flask 7, the polyetheretherketone probe 8 and the low-temperature twisted pair phosphor copper wire 6; Calculate the total heat influx; According to the law of conservation of heat, the total heat inflow and the heat of vaporization and density of liquid nitrogen are used to obtain the expression equation of the liquid nitrogen level change and the thermal conductivity and size of the material; According to the working time and size restrictions, the parameters of the non-magnetic glass Dewar flask 7, the polyetheretherketone probe 8 and the low-temperature twisted pair phosphor copper wire 6 are confirmed using an expression equation of the liquid nitrogen level change and the thermal conductivity and size of the material.

[0043] In one embodiment, see Figure 1 Combine Figure 4 As shown: Based on the superconducting electromagnetic observation system, a heat transfer model of the low-temperature system including the non-magnetic glass Dewar flask 7 is established, including the glass layer, vacuum insulation layer 72, silver coating layer 74 and blue aluminum coating 75 of the non-magnetic glass Dewar flask 7, the dimensions of the non-magnetic glass Dewar flask 7, the dimensions and thermal conductivity of the polyetheretherketone probe 8, and the thermal conductivity of the low-temperature twisted-pair phosphor copper wire 6 connecting the triaxial high-temperature superconducting sensor 5 and the readout circuit 9; In one embodiment, the polyetheretherketone probe 8 is made of polyetheretherketone, and its thermal conductivity is 0.25W / m·K; the low-temperature twisted pair phosphor copper wire 6 is made of phosphor copper wire, and its thermal conductivity is 25W / m·K; the non-magnetic glass Dewar flask 7 has an inner diameter of 40mm, an outer diameter of 80mm, and a height of 700mm; Based on the above parameters, the total heat inflow is calculated: based on the thermal conductivity and size of the materials, the heat conduction of the polyetheretherketone probe 8, the low-temperature twisted copper wire 6, and the glass layer, as well as the heat radiation from the glass layer to the vacuum insulation layer, are calculated. The sum of the two is the total heat inflow; Among them, the calculation formulas for the thermal radiation of the glass layer and the thermal radiation of the silver-plated layer are: , in, is room temperature, is the liquid nitrogen level, is the height of the vacuum insulation layer, is the thermal conductivity of glass, is the cross-sectional area of ​​the glass, is the thermal conductivity of silver plating, is the silver-plated cross-sectional area; where, Heat conduction through a conductor is: in, is the total heat conduction, is the thermal conductivity of liquid nitrogen, is the length of the PEEK probe in the non-magnetic glass Dewar flask, is the thermal conductivity of the PEEK probe, The thermal conductivity of low-temperature twisted-pair phosphor copper wire. The conductor here refers to the thermally conductive material other than the thermal insulator. Thermal radiation from insulating materials: ,in, is the Stefan-Boltzmann constant, is the efficiency coefficient, is the liquid nitrogen temperature; The total heat inflow is: ,in, is the thermal radiation of the glass layer, is the heat radiation of the silver plating layer, is the heat conduction of liquid nitrogen, Radiant heat from an insulating material.

[0044] Based on the heat conservation theorem, the relationship between the liquid nitrogen level and the cryogenic system is derived. Based on the external heat inflow and the vaporization heat and density of liquid nitrogen, the relationship between the liquid nitrogen level and the material coefficient and size is derived. ,in, is the temperature change of liquid nitrogen, is the cross-sectional area of ​​the non-magnetic glass Dewar flask, is the heat of vaporization of liquid nitrogen, is the density of liquid nitrogen, is the liquid level change of liquid nitrogen, is the total heat inflow.

[0045] In one embodiment, a non-magnetic glass Dewar flask 7 is made of 3.3 borosilicate glass, which has a vacuum insulation layer 72 and a silver coating 74, and an outer layer of blue aluminum coating 75, which has anti-magnetic and rust-proof properties; To address the problem of circuit heat dissipation difficulties in complex environments, further measures can be taken, including: using infrared thermal sensing equipment to record changes in circuit surface temperature, designing heat conduction joints with high thermal conductivity in areas where heat accumulates and is difficult to dissipate, increasing heat outflow, and thus reducing thermal noise caused by circuit heating.

[0046] To address the problem of circuit noise generation under the induction of high-frequency signals, aluminum alloy materials can be used to design circuit shielding covers to improve the shielding effectiveness of the circuit, thereby effectively reducing circuit noise. See also Figure 1 Combine Figure 2 、 Figure 3 as well as Figure 4 As shown, the electromagnetic signal superconducting observation system based on micro-shielding and thermal management of the present application is specifically implemented as follows: First, liquid nitrogen is filled into the non-magnetic glass Dewar flask 7. After checking the air tightness and water tightness of the device, a four-corner bracket with full counterweights and a pressure-resistant constant temperature container 13 are placed in the measurement area to test to ensure that the communication and power supply signals are correct.

[0047] A control signal is then sent through the remote control center 2. After being received and sent by the acquisition station 3, the control signal is transmitted to the interior of the pressure-resistant constant-temperature container 13 via the transmission cable 15 and the multi-core waterproof cable connector 14. The optical signal is converted into an electrical signal by the photoelectric converter 11 and input into the readout circuit controller 10, which then controls the operation of the readout circuit 9. The control signal of the readout circuit 9 is input into the triaxial high-temperature superconducting sensor 5 placed at the top of the polyetheretherketone probe 8 via the low-temperature twisted-pair phosphorus copper wire 6 in the polyetheretherketone probe 8, thereby starting the triaxial high-temperature superconducting sensor 5 and adjusting the triaxial high-temperature superconducting sensor 5 to the optimal operating point for long-period electromagnetic signal measurement. The electromagnetic signal collected by the triaxial high-temperature superconducting sensor 5 is output to the readout circuit 9 via the low-temperature twisted-pair phosphor copper wire 6. After being amplified, demodulated, filtered, and collected by the readout circuit 9, it is transmitted to the photoelectric converter 11. The photoelectric converter 11 converts the electrical signal into an optical signal and transmits it to the collection station 3 via the transmission cable 15. The collection station 3 then transmits the data returned by the transmission cable 15 to the remote control center 2 via the wireless communication system 4, thus completing the collection of the electromagnetic signal.

[0048] During electromagnetic exploration, see Figure 1 Combine Figure 2 and Figure 3 As shown, a carbon fiber support frame 16 and a non-magnetic aluminum alloy three-way connector 17 are formed into a four-corner bracket. The four-corner bracket can firmly fix the pressure-resistant constant temperature container 13 to prevent sloshing; the nitrogen release pipe 18 can discharge the nitrogen generated by the volatilization of liquid nitrogen to the ground to ensure normal air pressure in the equipment environment.

[0049] Finally, after the electromagnetic signal measurement in a certain measurement area is completed, the counterweights connected to the four corner brackets are released after closing the measurement signals of each part, and the relevant equipment can be recovered, thus completing the measurement work within a measurement area.

[0050] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. An electromagnetic signal superconducting observation system based on micro-shielding and thermal management, characterized in that: include: The high-temperature sensor unit includes a pressure-resistant constant-temperature container, a non-magnetic glass Dewar flask placed in the pressure-resistant constant-temperature container, and a three-axis high-temperature superconducting sensor is arranged in the non-magnetic glass Dewar flask. The pressure-resistant constant-temperature container includes a base body made of carbon fiber reinforced plastic, and a low-frequency selective shielding layer, an insulating thin layer, an absorption layer and a high-frequency shielding layer are sequentially arranged outside the base body.

2. The electromagnetic signal superconducting observation system based on micro-shielding and thermal management according to claim 1 is characterized in that: Calculate the shielding effectiveness curves of different layers and materials of the pressure-resistant constant temperature container, determine the shielding material and thickness of each layer, sum the shielding effectiveness curves of each layer to obtain a total shielding effectiveness curve, and make the total shielding effectiveness within the target frequency range in the total shielding effectiveness curve of the selected shielding material and thickness meet the minimum total shielding effectiveness required by the design.

3. The electromagnetic signal superconducting observation system based on micro-shielding and thermal management according to claim 1 or 2, characterized in that: The high-frequency shielding layer is configured as a metal grid structure.

4. The electromagnetic signal superconducting observation system based on micro-shielding and thermal management according to claim 1 or 2, characterized in that: The absorption layer is made of conductive rubber or radio frequency absorbing foam.

5. The electromagnetic signal superconducting observation system based on micro-shielding and thermal management according to claim 1 is characterized in that: The non-magnetic glass Dewar flask is filled with liquid nitrogen, and a three-axis high-temperature superconducting sensor is fixed at one end of a polyetheretherketone probe. The three-axis high-temperature superconducting sensor is connected to the low-temperature twisted-pair phosphor copper wire in the polyetheretherketone probe. The other end of the polyetheretherketone probe extends out of the bottle mouth of the non-magnetic glass Dewar flask, and the bottle mouth is sealed by an insulating insulator. The polyetheretherketone probe is connected to the collection circuit through the low-temperature twisted-pair phosphor copper wire. The output end of the collection circuit extends out of the pressure-resistant constant temperature container through a multi-core waterproof cable connector, and transmits the collected electromagnetic signal to the collection station via a transmission cable.

6. The electromagnetic signal superconducting observation system based on micro-shielding and thermal management according to claim 5, characterized in that: The non-magnetic glass Dewar flask comprises two glass layers, with a vacuum insulation layer between the two glass layers. The outer side of the inner glass layer is provided with a silver coating, and the outer side of the outer glass layer is provided with a blue aluminum coating.

7. The electromagnetic signal superconducting observation system based on micro-shielding and thermal management according to claim 6, characterized in that: The parameters of the non-magnetic glass Dewar flask, polyetheretherketone probe, and low-temperature twisted-pair phosphorus copper wire satisfy the expression equation of the liquid nitrogen level change and the thermal conductivity and size of the material: ,in, is the temperature change of liquid nitrogen, is the cross-sectional area of ​​the non-magnetic glass Dewar flask, is the heat of vaporization of liquid nitrogen, is the density of liquid nitrogen, is the liquid level change of liquid nitrogen, is the total heat inflow; The total heat influx: ,in, is the thermal radiation of the glass layer, is the heat radiation of the silver plating layer, is the heat conduction of liquid nitrogen, It is the radiant heat of the insulating body; The heat radiation of the inner glass layer and the silver coating is: , where is room temperature, is the liquid nitrogen level, is the height of the vacuum insulation layer, is the thermal conductivity of glass, is the cross-sectional area of ​​the glass, is the thermal conductivity of silver plating, is the silver-plated cross-sectional area; ,in, is the total heat conduction, is the thermal conductivity of liquid nitrogen, is the length of the PEEK probe in the non-magnetic glass Dewar flask, is the thermal conductivity of the PEEK probe, is the thermal conductivity of low-temperature twisted-pair phosphor copper wire; Thermal radiation from insulating materials: ,in, is the Stefan-Boltzmann constant, is the efficiency coefficient, is liquid nitrogen temperature.

8. A design method for an electromagnetic signal superconducting observation system based on micro-shielding and thermal management according to any one of claims 1 to 7, characterized in that: include: The frequency band to be shielded is selected according to the signal to be detected, and the outer layer of the pressure-resistant constant temperature container is set as a low-frequency selective shielding layer, an absorption layer and a high-frequency shielding layer according to the frequency band to be shielded; Calculate the shielding effectiveness curves of different layers and materials of the pressure-resistant constant temperature container, determine the shielding material and thickness of each layer, sum the shielding effectiveness curves of each layer to obtain the total shielding effectiveness curve, and make the total shielding effectiveness within the target frequency range in the total shielding effectiveness curve of the selected shielding material and thickness meet the minimum total shielding effectiveness required by the design.

9. The design method of the electromagnetic signal superconducting observation system based on micro-shielding and thermal management according to claim 8, characterized in that: Also includes: Establishing a heat transfer model including thermal conductivity and dimensions of materials, the heat transfer model including a non-magnetic glass Dewar flask, a polyetheretherketone probe, and a low-temperature twisted-pair phosphor copper wire; Calculate the total heat influx; According to the law of conservation of heat, the total heat inflow and the heat of vaporization and density of liquid nitrogen are used to obtain the expression equation of the liquid nitrogen level change and the thermal conductivity and size of the material; Based on the working time and size restrictions, the parameters of the non-magnetic glass Dewar flask, polyetheretherketone probe and low-temperature twisted-pair phosphor copper wire are confirmed using an expression equation that combines the liquid nitrogen level change with the thermal conductivity and size of the material.

10. The design method of the electromagnetic signal superconducting observation system based on micro-shielding and thermal management according to claim 8, characterized in that: The expression equation of liquid nitrogen level change and material thermal conductivity and size is: ,in, is the temperature change of liquid nitrogen, is the cross-sectional area of ​​the non-magnetic glass Dewar flask, is the heat of vaporization of liquid nitrogen, is the density of liquid nitrogen, is the liquid level change of liquid nitrogen, is the total heat inflow; The total heat inflow is: ,in, is the thermal radiation of the glass layer, is the heat radiation of the silver plating layer, is the heat conduction of liquid nitrogen, It is the radiant heat of the insulating body; The heat radiation of the inner glass layer and the silver coating is: ,in, is room temperature, is the liquid nitrogen level, is the height of the vacuum insulation layer, is the thermal conductivity of glass, is the cross-sectional area of ​​the glass, is the thermal conductivity of silver plating, is the cross-sectional area of ​​the silver-plated layer; ,in, is the total heat conduction, is the thermal conductivity of liquid nitrogen, is the length of the PEEK probe in the non-magnetic glass Dewar flask, is the thermal conductivity of the PEEK probe, is the thermal conductivity of low-temperature twisted-pair phosphor copper wire; Thermal radiation from insulating materials: ,in, is the Stefan-Boltzmann constant, is the efficiency coefficient, is liquid nitrogen temperature.

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