Magnetic impurity simulation method, device and system based on current dipole

Abstract

The invention discloses a current dipole-based magnetic impurity simulation method, device and system, belongs to the technical field of nondestructive testing, and solves the problem of how to improve the magnetic impurity simulation precision. Comprising the steps of inputting simulation parameters of target magnetic impurity particles, calculating target driving current, introducing a medium correction coefficient to perform reverse correction on the target driving current, and solving actual driving current; actual driving current is applied to the current dipole array of the selected level, and a simulated magnetic field is generated; an analog magnetic field signal is extracted based on a phase-locked amplification technology and is used for magnetic field signal inversion verification or sensitivity calibration. According to the method, the magnetic moment generated by the current dipole is equivalent to the excitation moment of the magnetic impurities, the medium correction coefficient k is introduced to carry out reverse correction on the target driving current, the actual driving current is solved, and the magnitude mapping relation from the magnetic impurity particle parameters to the actual driving current is established; and the accuracy and reliability of sensitivity calibration of the quantum detection equipment are improved.

Description

Technical Field

[0001] This invention belongs to the field of extremely weak magnetic field measurement and non-destructive testing technology, and relates to a method, device and system for simulating magnetic impurities based on current dipoles. Background Technology

[0002] Low-abundance magnetic impurities refer to atoms or ions with magnetic moments present in materials at extremely low concentrations, such as iron, cobalt, nickel, and manganese, with concentrations in the ppm or ppb range. In the fields of new energy (such as lithium iron phosphate battery materials), energy storage, and powder metallurgy, trace amounts of magnetic impurities mixed into materials can seriously affect product safety performance. Existing literature, such as "Research and Application of Key Technologies of Closed-Loop SERF Atomic Magnetometer" (Guo Qingqian, Biomedical Engineering. [D]. University of Science and Technology of China [2026-03-26].), discloses the use of high-sensitivity quantum magnetometers such as SERF atomic magnetometers to detect low-abundance magnetic impurities. However, the following problems still exist in the process of detecting low-abundance magnetic impurities in industrial materials:

[0003] (1) Calibration difficulties: The diameter of real micro magnetic particles is usually in the range of 10μm to 100μm, making it difficult to accurately fix the particle position and control the magnetic moment of the particles, resulting in a large quantitative calibration error of the sensitivity of the detection equipment.

[0004] (2) Simulation of background interference: Some substrate materials (such as lithium iron phosphate materials) have high magnetic background. Their permeability and magnetic susceptibility will produce nonlinear enhancement or shielding effects on impurity signals. Existing simulation devices cannot simulate the coupling of impurity signals with high background environment, resulting in a large deviation between laboratory calibration results and actual production line conditions.

[0005] (3) Poor technical adaptability: Traditional simulation devices based on liquids or powders are complex in structure, and the medium cannot simulate the complex magnetic properties of industrial powder materials (such as magnetic circuit distortion caused by magnetic permeability μ), which makes them unsuitable for direct application in the calibration of industrial-grade low-abundance magnetic impurity detection equipment.

[0006] (4) Insufficient cost and flexibility: Existing technologies are difficult to achieve rapid switching of multiple layers and multiple positions to simulate different working conditions, and cannot meet the inversion verification requirements of automated inspection lines for defects of different depths, thus limiting the R&D efficiency and accuracy improvement of inspection equipment.

[0007] Therefore, there is an urgent need to provide a solution that is simple in structure, low in cost, and can accurately simulate magnetic impurity signals of different depths and intensities, in order to solve the problems of signal inversion verification and sensitivity calibration in the research and development process of quantum detection equipment. Summary of the Invention

[0008] The technical problem to be solved by this invention is how to improve the simulation accuracy of magnetic impurities.

[0009] The present invention solves the above-mentioned technical problems through the following technical solutions: The magnetic impurity simulation method based on current dipoles includes the following steps: A sample container is filled with substrate powder, and a multi-level current dipole array is embedded in the substrate powder and fixed at different depths inside the sample container. Input the simulation parameters of the target magnetic impurity particles, calculate the target driving current, introduce a dielectric correction coefficient to reverse the target driving current, and solve for the actual driving current. An actual driving current is applied to the current dipole array at a selected level to generate a simulated magnetic field; Simulated magnetic field signals are extracted using lock-in amplification technology and used for magnetic field signal inversion verification or sensitivity calibration.

[0010] Furthermore, the method also includes: By using a multi-channel switching matrix to select the current dipole arrays at different levels for energization, the magnetic field attenuation characteristics at different burial depths can be simulated.

[0011] Furthermore, the substrate powder is a non-magnetic powder or a base powder with a specific magnetic permeability.

[0012] Furthermore, the calculation of the target drive current specifically involves: First, for a spherical magnetic particle with radius R, solve for its excited magnetic moment. :

[0013] in, Let the diameter be , satisfying the mathematical relation D=2R. The magnetic susceptibility of the substrate powder is given. To excite the magnetic field strength; Next, the equivalent magnetic moment generated by the current dipole is solved. :

[0014] in, The number of turns of the coil in the current dipole. For equivalent area, For target drive current; Then, making them equivalent, the target driving current is calculated. : .

[0015] Furthermore, the medium correction factor is calibrated through the following steps: First, the amplitude of the reference magnetic field B0 was measured under substrate-free powder conditions; Next, the magnetic field amplitude B1 was measured after filling the target substrate powder. Finally, define the correction factor. .

[0016] Furthermore, the actual drive current Using the following logical representation:

[0017] in, The target drive current is denoted by k, and k is a correction factor.

[0018] The present invention also provides a magnetic impurity simulation device based on current dipoles, comprising a sample container, a support frame, a current dipole array, leads, and substrate powder; the sample container has multiple layers of support frames arranged sequentially along the axial direction of the sample container, and a current dipole array is mounted on the surface of each layer of support frame; the leads are of a twisted-pair structure, extending out in a direction perpendicular to the plane where the current dipole array is located, and are arranged on the inner wall of the sample container; the sample container is filled with substrate powder, and the current dipole array is embedded in the substrate powder.

[0019] Furthermore, the simulation device also includes a signal generator; the signal generator includes at least a control unit, a digital-to-analog converter, a voltage-controlled current source, and a current closed-loop detection module; the control unit controls the digital-to-analog converter to output an analog voltage according to the driving current value, which is converted into an output current by the voltage-controlled current source, and the current closed-loop detection module monitors the output current in real time and feeds it back to the control unit.

[0020] Furthermore, the simulation device also includes a multiplexing matrix; the two ends of the multiplexing matrix are respectively connected to a signal generator and a current dipole array, and are used to switch different levels of current dipole arrays to apply the output current to the selected current dipole array.

[0021] The present invention also provides a magnetic impurity simulation system based on current dipoles, comprising: The above-mentioned magnetic impurity simulation device based on current dipoles is used; A quantum magnetometer is used to collect the simulated magnetic field signals generated by the simulation device. The controller is connected to the quantum magnetometer and the simulation device respectively, and is used to execute the above-described magnetic impurity simulation method based on current dipoles.

[0022] The advantages of this invention are: (1) In this invention, a signal generator is used to form a conductive path with the current dipole sample container through a lead wire. After the weak current is conducted to the current dipole simulator, an equivalent magnetic moment is generated to simulate the magnetic field of magnetic impurity particles. The current dipole array is set in multiple layers in the sample container. A three-dimensional spatial coordinate array can be formed at different layers. When the current dipole array at different layers is switched to the current dipole array at different levels and energized, the magnetic field attenuation characteristics of impurities at different burial depths can be simulated. Furthermore, this invention equates the magnetic moment generated by the current dipole to the excitation moment of the magnetic impurities, thereby deriving the target driving current for simulation. Considering the nonlinear influence of the substrate powder on the magnetic field, a dielectric correction coefficient k is introduced to inversely correct the target driving current, thus solving for the actual driving current and establishing a magnitude mapping relationship from the magnetic impurity particle parameters to the actual driving current. This invention enables the automatic calculation of the driving current by inputting target particle parameters. Compared to existing technologies that struggle to accurately fix and control real magnetic particles, this invention achieves quantitative and traceable simulation of impurity magnetic field signals, significantly improving the accuracy and reliability of sensitivity calibration for quantum detection equipment.

[0023] (2) The present invention introduces a substrate powder magnetic effect compensation mechanism. The substrate powder not only serves as the physical support of the current dipole, but also as the magnetic field conduction medium, which generates a nonlinear enhancement or shielding effect on the magnetic field generated by the current dipole. In addition, the present invention can select the corresponding industrial powder as the substrate powder for filling according to the actual calibration requirements. Different substrate powders have corresponding permeability μ and magnetic susceptibility χ, which can simulate the magnetic circuit change of weak impurity magnetic signals by real industrial materials under different working conditions, thereby providing a calibration environment for quantum detectors that is closer to the working conditions of the production line and improving the simulation accuracy of magnetic media under different working conditions.

[0024] (3) This invention addresses the need for detecting extremely low abundance (ppb level) magnetic impurities by designing a high-precision micro-current driving scheme. Through a high bit depth digital-to-analog converter and a precision voltage-controlled current source, it can stably drive analog currents in the picoampere (pA) to nanoampere (nA) range. Combined with miniaturized current dipoles (electrode spacing d < 1 mm), this invention can accurately simulate extremely weak magnetic fields in the range of 10 fT to 1000 pT generated in space by a single hard or soft magnetic particle with a diameter in the range of 10 μm to 100 μm, realizing equivalent miniaturized simulation from physical entities to electromagnetic signals.

[0025] (4) In this invention, the lead structure adopts a zero-magnetic-bias twisted-pair structure. The lead is led out along the direction perpendicular to the plane where the current dipole array is located and is laid on the inner wall of the sample container. The electromagnetic waves radiated by each wire during transmission are canceled by the electromagnetic waves emitted by the other wire. The twisted-pair structure makes the current direction in adjacent wires opposite, thereby achieving magnetic field vector cancellation in the region close to the micro coil and significantly reducing parasitic magnetic field interference. Attached Figure Description

[0026] Figure 1 This is a flowchart of a magnetic impurity simulation method based on a current dipole according to Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the longitudinal section of the magnetic impurity simulation device based on a current dipole according to Embodiment 1 of the present invention. Figure 3 This is a schematic diagram of the current dipole simulator structure and lead wire structure according to Embodiment 1 of the present invention; Figure 4 This is a schematic diagram of the execution logic for controlling the drive current using a signal generator, according to Embodiment 1 of the present invention. Reference numerals: 1. Sample container; 2. Support frame; 3. Current dipole array; 4. Lead wire; 5. Substrate powder. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments: Example 1 This embodiment provides a dedicated simulation device for detecting magnetic impurities in industrial materials based on current dipoles. It is applied in the research and calibration process of quantum magnetometers. It simulates the extremely weak magnetic field signals generated by low-abundance magnetic impurities and supports the inversion verification of impurity signals with different burial depths and intensities.

[0029] In a preferred embodiment, the quantum magnetometer is specifically a SERF atomic magnetometer, and the low-abundance magnetic impurity is specifically a ppb-level magnetic impurity.

[0030] like Figure 2As shown, specifically, the present invention discloses a magnetic impurity simulation device based on current dipoles, including a sample container 1, a support frame 2, a current dipole array 3, a lead wire 4, and a substrate powder 5; the sample container 1 is provided with multiple layers of support frames 2, and a current dipole array 3 is installed on the surface of each layer of support frame 2; The lead wire 4 adopts a zero magnetic bias twisted pair structure, is led out along the direction perpendicular to the plane where the current dipole array 3 is located, and is arranged on the inner wall of the sample container 1. The sample container 1 is filled with substrate powder 5, and the current dipole array 3 is embedded in the substrate powder 5.

[0031] In this embodiment, the sample container 1 is used to hold the substrate powder 5 to simulate the actual test conditions. According to the actual calibration requirements, the sample container 1 is made of non-magnetic organic glass and can be any three-dimensional structure such as cylindrical structure or square column structure (i.e., prismatic structure). The size of the sample container 1 can match the actual production line testing area.

[0032] In a preferred embodiment, the sample container 1 may be made of acrylic (polymethyl methacrylate) material and have a cylindrical structure, such as... Figure 2 As shown.

[0033] In this embodiment, the substrate powder 5 can be a non-magnetic powder or a background powder with specific permeability μ and magnetic susceptibility χ. The substrate powder 5 is filled with corresponding industrial powder according to actual calibration requirements. The substrate powder 5 not only serves as the physical support for the current dipole but also as a magnetic field conduction medium, producing a nonlinear enhancement or shielding effect on the magnetic field generated by the current dipole. Figure 2 As shown, the interior of the sample container 1 is filled with base powder 5, and the bottom of the sample container 1 is filled with base powder 5 for observation.

[0034] In a preferred embodiment, if the simulation device is used to simulate the detection of magnetic impurities in the substrate material of new energy batteries, a background powder such as lithium iron phosphate powder is selected; if the simulation device is only used for basic sensitivity calibration, a non-magnetic powder such as high-purity CMC powder is selected to fill the sample container 1, or the sample container 1 is left empty, that is, the substrate powder 5 is not put in for calibration simulation.

[0035] Furthermore, the support frame 2 has multiple micro positioning grooves on its surface. The positioning grooves are fixedly connected to the current dipole simulator and are used to fix the position of the entire current dipole array 3 on the surface of the support frame 2, rigidly locking the three-dimensional coordinate position of the current dipole array 3, and preventing the current dipole array 3 from shifting or tilting during the filling of the substrate powder 5 or the vibration of the sample container 1, which would affect the calibration results.

[0036] The support frame 2 has at least three layers arranged sequentially along the axial direction of the sample container 1, referred to as the upper layer, middle layer and lower layer, so that the current dipole simulator can form a three-dimensional spatial coordinate array at different levels. When the current dipole array 3 at different levels is switched and energized, the attenuation characteristics of the impurity magnetic field at different burial depths can be simulated.

[0037] In this embodiment, the support frame 2 is specifically a non-magnetic support frame 2, made of a low magnetic susceptibility material; preferably, the low magnetic susceptibility material can be alumina ceramic or 3D printing photosensitive resin.

[0038] like Figure 3 As shown in the left half, the current dipole array 3 includes multiple current dipole simulators arranged in an array on the surface of the support frame 2; each current dipole simulator consists of a pair of micro coils with a spacing of d, in μm; the number of turns of the micro coils is N, and the equivalent area is A.

[0039] like Figure 3 As shown in the right half, the lead wire 4 structure adopts a zero-magnetic-bias twisted-pair structure. The lead wire 4 is led out along the direction perpendicular to the plane where the current dipole array 3 is located and is arranged on the inner wall of the sample container 1. In this embodiment, the twisted-pair specifically refers to the lead wire 4 structure formed by insulated wires twisted together. The electromagnetic waves radiated by each wire during transmission are canceled by the electromagnetic waves emitted by the other wire. The twisted-pair structure makes the current direction in adjacent wires opposite, thereby achieving magnetic field vector cancellation in the area close to the micro coil and significantly reducing parasitic magnetic field interference.

[0040] Furthermore, the simulation device also includes a signal generator (not shown) and a multiplexing matrix (not shown); the signal generator is used to generate a weak current that simulates a magnetic impurity signal, and the two ends of the multiplexing matrix are connected to the signal generator and the current dipole array 3, respectively, for switching different levels of the current dipole array 3.

[0041] In a preferred embodiment, the weak current generated by the signal generator is in the pA to nA range; the multiplexing matrix can be a low thermoelectric relay or a high-precision analog switch; the signal generator forms a conductive path with the current dipole simulator through lead 4, and the weak current is conducted to the current dipole simulator to generate an equivalent magnetic moment to simulate the magnetic field of magnetic impurity particles; and the multiplexing matrix can be used to achieve seamless switching between the current dipole simulators of the upper, middle and lower layers.

[0042] like Figure 1 As shown, this invention also discloses a method for simulating magnetic impurities based on current dipoles, comprising the following steps: S1, fill the sample container with substrate powder, and embed the multi-level current dipole array in the substrate powder, fixing them at different depths inside the sample container.

[0043] In this embodiment, the substrate powder is filled with corresponding industrial powder according to the calibration requirements. The substrate powder can be a non-magnetic powder or a background powder with specific magnetic permeability μ and magnetic susceptibility χ. The substrate powder is filled with corresponding industrial powder according to the actual calibration requirements. Preferably, if the simulation method is used to simulate the detection of magnetic impurities in new energy battery substrate materials, a background powder such as lithium iron phosphate powder is selected. If the simulation method is only used for basic sensitivity calibration, a non-magnetic powder such as high-purity CMC powder is selected to fill the sample container, or the sample container is left empty.

[0044] In this embodiment, the current dipole array has at least three layers, arranged sequentially along the axial direction of the sample container, and referred to as the upper layer, middle layer and lower layer, so that the current dipole simulator in each layer can form a three-dimensional spatial coordinate array at different levels. When switching to different levels of the current dipole array and energizing, the attenuation characteristics of the impurity magnetic field at different burial depths in the sample container can be simulated.

[0045] S2, Input the simulation parameters of the target magnetic impurity particles, including diameter D, magnetic susceptibility χ, and excitation magnetic field strength. The parameters of the current dipole simulator include the number of coil turns N and the equivalent area A.

[0046] In this embodiment, each current dipole array includes multiple current dipole simulators arranged in an array on the surface of the support frame inside the sample container. Each current dipole simulator consists of a pair of micro coils with a spacing of d (in μm). The number of turns of the micro coils is N, and the equivalent area is A. The magnetic susceptibility χ is determined by the properties of the filling substrate powder itself. The intensity of the external excitation magnetic field is used to describe the degree of magnetization of magnetic impurity particles under the action of an external magnetic field.

[0047] S3, Calculate the target drive current Based on the physical model and the mapping relationship between quantities, the target driving current required for the target magnetic impurity particles is calculated. Specifically, for a spherical magnetic particle with radius R, its excited magnetic moment... Using the following logical representation:

[0048] Furthermore, substituting the diameter D=2R into the above equation, we get:

[0049] The equivalent magnetic moment generated by the current dipole simulator in the simulation device Using the following logical representation:

[0050] By making the two equivalent, the target driving current is obtained. This can be represented using the following logic:

[0051] Furthermore, the spherical magnetic particles serve only as an equivalent model for calculating the magnetic moment. Since in the far-field region of a magnetic field, the magnetic field of any shape of magnet can be equivalently represented as a magnetic dipole field generated by a current dipole, the only influencing factor between the magnetic impurities and the equivalent current dipole is the magnetic moment, independent of the specific geometry. In addition, magnetic impurity particles exhibit uniform magnetization, isotropy, and no demagnetizing factor directionality. Therefore, the magnetic field of non-spherical magnetic impurity particles can be mapped to the spherical model through an equivalent magnetic moment.

[0052] S4, Dielectric Correction: Considering the nonlinear effect of the substrate powder on the magnetic field, a dielectric correction coefficient k is introduced for the target driving current. Perform reverse correction, and the corrected actual drive current for:

[0053] The correction coefficient k is determined through the following steps: First, the amplitude of the reference magnetic field B0 was measured under conditions of no substrate powder (near vacuum). Next, the magnetic field amplitude B1 was measured after filling the target substrate powder. Finally, define the correction factor. Using correction coefficients During subsequent calibration, the output current is corrected in reverse to ensure the actual drive current of the output is corrected. It is closer to real working conditions.

[0054] Furthermore, this embodiment also selects different levels of current dipole arrays to be energized through a multi-channel switching matrix to simulate the attenuation characteristics of impurity magnetic fields at different burial depths.

[0055] Preferably, the multi-channel switching matrix can be a low thermoelectric relay or a high-precision analog switch.

[0056] In this embodiment, the reference magnetic field amplitude B0 can be obtained through static local measurement before filling the substrate powder, such as... Figure 1 As shown.

[0057] S5, Current Output and Closed-Loop Control: Apply the actual drive current to the current dipole array of the selected level. This generates a simulated magnetic field.

[0058] like Figure 4 As shown, the signal generator includes at least a control unit, a digital-to-analog converter, a voltage-controlled current source, and a current closed-loop detection module. The control unit (MCU) controls the digital-to-analog converter to output an analog voltage according to the corrected actual drive current value, which is then converted into an output current by the voltage-controlled current source. The current closed-loop detection module monitors the output current in real time and feeds it back to the control unit.

[0059] Preferably, the digital-to-analog converter (DAC) can be a high-bit-depth DAC of at least 24 bits, which, together with a precision voltage-controlled current source, enables stable driving of analog currents in the pA to nA range; the closed-loop monitoring module includes a high-precision sampling resistor and a transimpedance amplifier for real-time monitoring of the output drive current. This information is then fed back to the control unit for dynamic correction.

[0060] S6, Signal Acquisition and Calibration: Based on lock-in amplification technology, simulated magnetic field signals are extracted for magnetic field signal inversion verification or sensitivity calibration.

[0061] like Figure 4 As shown, the signal generator also includes a lock-in amplifier for extracting extremely weak simulated magnetic field signals from a noisy environment. Specifically, a preset modulation frequency is first applied to the driving current, causing the current dipole to generate a modulated magnetic field of the corresponding frequency. This magnetic field is acquired by a quantum magnetometer and converted into an electrical signal output. The electrical signal is then input to the lock-in amplifier, which performs phase-sensitive detection on the signal based on a reference modulation frequency, extracting only the target modulation frequency component and filtering out noise at other frequencies. This process effectively extracts the extremely weak simulated magnetic field signal buried in strong background noise, thereby suppressing noise and improving the signal-to-noise ratio of the weak simulated magnetic field signal.

[0062] Furthermore, in extremely weak magnetic field measurements (on the order of 10 fT to 1000 pT), lock-in amplifiers are susceptible to nonlinear factors, leading to phenomena such as entering the saturation region or noise levels below the noise floor. Therefore, as... Figure 1 As shown, it is determined whether the input and output relationship of the lock-in amplifier meets the linearity requirement. If it does, the calibration result is output. If it does not, S6 is executed again and the lock-in amplifier re-extracts the magnetic field signal. The calibration result includes the mapping relationship between the magnetic field amplitude and the driving current (represented by the BI curve), the linear interval, and the dynamic range.

[0063] Preferably, the linearity determination can be performed using any existing linearity determination method, such as multi-point measurement, dynamic range verification, or harmonic distortion monitoring.

[0064] In this embodiment, to verify that the method proposed in this invention can achieve equivalent miniaturized simulation of extremely low abundance (ppb level) magnetic impurities, that is, to accurately simulate the extremely weak magnetic field of 10fT to 1000pT generated in space by a single hard or soft magnetic particle with a diameter in the range of 10μm to 100μm, the following verification is carried out from two aspects: theoretical calculation and current dipole equivalence. The specific contents are as follows: (1) Theoretical calculation: According to the far-field model of the magnetic dipole, the magnetic induction intensity generated by a single magnetic particle at a certain point in space can be approximately expressed as:

[0065] in, The magnetic flux density at a distance r from the center of the particle is expressed in tons (T). The permeability of free space, Let be the equivalent magnetic moment of the magnetic particle, which is known. (Obtained from step S3).

[0066] To cover typical operating conditions for industrial magnetic impurity detection, the following parameter ranges are selected for estimation using Table 1 below: Table 1. Simulation Parameter Values ​​under Typical Operating Conditions

[0067] Substituting the above parameters into the formula, the range of the equivalent magnetic moment of the magnetic particles is calculated as follows: Substituting further into the formula for magnetic induction intensity, and taking the measured distance... The corresponding magnetic field strength range is approximately .

[0068] The theoretical calculations above show that, under typical industrial testing conditions, the magnetic field signal generated by magnetic particles with diameters ranging from 10 μm to 100 μm is indeed on the order of 10 fT to 1000 pT. Therefore, to achieve an equivalent simulation of this type of impurity, the simulation device must be able to generate an extremely weak magnetic field of the same magnitude.

[0069] (2) Verification of the equivalent current dipole: In this embodiment, a miniature current dipole is used as the magnetic field generating element, and its equivalent magnetic moment And the following parameter ranges are selected from Table 2 below for estimation: Table 2. Parameter values ​​for miniature current dipoles

[0070] Substituting the above parameters into the formula, the range of the equivalent magnetic moment generated by the current dipole is approximately [value missing]. The equivalent magnetic moment Substituting into the far-field formula for a magnetic dipole, and taking the measured distance... The corresponding magnetic field strength range is approximately 0.5fT to 50pT.

[0071] It should be noted that the above calculations are based on an ideal dipole model. In actual measurement, factors such as measurement distance, spatial orientation, and the non-ideal structure of the current dipole will all affect the magnetic field amplitude. Taking these factors into account, the actual magnetic field range that the device of this invention can simulate can be extended to approximately 1 fT to 100 pT, which is basically consistent with the magnetic field range (10 fT to 1000 pT) generated by magnetic particles in the aforementioned theoretical verification, and fully covers the signal magnitude requirements under typical detection conditions.

[0072] In summary, the device of this invention addresses the detection requirements of extremely low abundance (ppb level) magnetic impurities by designing a high-precision micro-current driving scheme. Through a high bit-depth digital-to-analog converter and a precision voltage-controlled current source, the device can stably drive analog currents in the picoampere (pA) to nanoampere (nA) range. Combined with miniaturized current dipoles (electrode spacing d < 1 mm), this invention can accurately simulate extremely weak magnetic fields in space, ranging from 10 fT to 1000 pT, generated by a single hard or soft magnetic particle with a diameter in the range of 10 μm to 100 μm, achieving equivalent miniaturized simulation from physical entities to electromagnetic signals.

[0073] The present invention also discloses a magnetic impurity simulation system based on current dipoles, including a magnetic impurity simulation device based on current dipoles as described in Embodiment 1, a controller, and a quantum magnetometer; The quantum magnetometer is used to collect the simulated magnetic field signal generated by the simulation device; The controller is connected to a quantum magnetometer and a simulation device, respectively, and is used to execute the magnetic impurity simulation method based on current dipoles described in Embodiment 1.

[0074] It should be noted that the logic and / or steps represented in the flowchart or otherwise described herein can be considered as a ordered list of executable instructions for implementing logical functions. This can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-based system, or other system that can fetch and execute instructions from, or in conjunction with, such an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include: electrical connections having one or more wires (electronic devices), portable computer disk drives (magnetic devices), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CD-ROM). Alternatively, the computer-readable medium may be paper or other suitable media on which the program can be printed, since the program can be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in a computer memory.

[0075] It should be understood that various parts of the present invention can be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. If implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0076] In the description of this specification, references to terms such as "in a preferred embodiment," "preferred," "in this embodiment," "specific," or "furthermore," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0077] In this specification, unless otherwise stated, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly defined. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0078] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for simulating magnetic impurities based on current dipoles, characterized in that, Includes the following steps: A sample container is filled with substrate powder, and a multi-level current dipole array is embedded in the substrate powder and fixed at different depths inside the sample container. Input the simulation parameters of the target magnetic impurity particles, calculate the target driving current, introduce a dielectric correction coefficient to reverse the target driving current, and solve for the actual driving current. An actual driving current is applied to the current dipole array at a selected level to generate a simulated magnetic field; Simulated magnetic field signals are extracted using lock-in amplification technology and used for magnetic field signal inversion verification or sensitivity calibration.

2. The magnetic impurity simulation method based on current dipoles according to claim 1, characterized in that, The method further includes: By using a multi-channel switching matrix to select the current dipole arrays at different levels for energization, the magnetic field attenuation characteristics at different burial depths can be simulated.

3. The magnetic impurity simulation method based on current dipoles according to claim 1, characterized in that, The substrate powder is a non-magnetic powder or a base powder with a specific magnetic permeability.

4. The magnetic impurity simulation method based on current dipoles according to claim 1, characterized in that, The calculation of the target driving current specifically involves: First, for a spherical magnetic particle with radius R, solve for its excited magnetic moment. : in, Let the diameter be , satisfying the mathematical relation D=2R. The magnetic susceptibility of the substrate powder is given. To excite the magnetic field strength; Next, the equivalent magnetic moment generated by the current dipole is solved. : in, The number of turns of the coil in the current dipole. For equivalent area, For target drive current; Then, making them equivalent, the target driving current is calculated. : 。 5. The magnetic impurity simulation method based on current dipoles according to claim 4, characterized in that, The medium correction factor is calibrated through the following steps: First, the amplitude of the reference magnetic field B0 was measured under substrate-free powder conditions; Next, the magnetic field amplitude B1 was measured after filling the target substrate powder. Finally, define the correction factor. .

6. The magnetic impurity simulation method based on current dipoles according to claim 1, characterized in that, The actual drive current Using the following logical representation: in, The target drive current is denoted by k, and k is a correction factor.

7. A magnetic impurity simulation device based on current dipoles, characterized in that, The sample container includes a sample container, a support frame, a current dipole array, leads, and substrate powder. The sample container has multiple layers of support frames arranged sequentially along the axial direction of the sample container, and a current dipole array is mounted on the surface of each support frame. The leads are of a twisted-pair structure and are led out in a direction perpendicular to the plane where the current dipole array is located, and are arranged on the inner wall of the sample container. The sample container is filled with substrate powder, and the current dipole array is embedded in the substrate powder.

8. The magnetic impurity simulation device based on current dipoles according to claim 7, characterized in that, The simulation device also includes a signal generator; the signal generator includes at least a control unit, a digital-to-analog converter, a voltage-controlled current source, and a current closed-loop detection module; the control unit controls the digital-to-analog converter to output an analog voltage according to the driving current value, which is converted into an output current by the voltage-controlled current source, and the current closed-loop detection module monitors the output current in real time and feeds it back to the control unit.

9. The magnetic impurity simulation device based on current dipoles according to claim 8, characterized in that, The simulation device also includes a multiplexing matrix; the two ends of the multiplexing matrix are respectively connected to a signal generator and a current dipole array, and are used to switch different levels of current dipole arrays to apply the output current to the selected current dipole array.

10. A magnetic impurity simulation system based on current dipoles, characterized in that, include: The magnetic impurity simulation device based on current dipoles as described in any one of claims 7 to 9 is used; A quantum magnetometer is used to collect the simulated magnetic field signals generated by the simulation device. The controller is connected to the quantum magnetometer and the simulation device respectively, and is used to execute the magnetic impurity simulation method based on current dipole as described in any one of claims 1 to 6.

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