Magnetic moment comparator device and measuring method

Abstract

The invention discloses a magnetic moment comparator device and a measurement method. The magnetic moment of the current-carrying standard coil is in direct proportion to the magnetic field generated at a fixed distance on the axis, and according to the principle that a magnetic dipole layer and the current-carrying coil have equivalence in electromagnetism, when the space magnetic field can be accurately measured, the current-carrying standard coil can be used for measuring the magnetic moment of a magnetic sample at the same position. A magnetic moment comparator is designed in a magnetic shielding cylinder, an atomic magnetometer is used for measuring an absolute magnetic field with high sensitivity, a current-carrying standard coil is placed at the position, with the distance being r0, of one side of an atomic gas chamber in the direction of a background magnetic field, and the axis of the current-carrying standard coil is parallel to the direction of the background magnetic field; the magnetic moment direction of the magnetic sample is parallel to the background magnetic field direction, when the magnetic sample is moved by the sample transfer rod to the position, which is r0 away from the atomic gas chamber, of the other side of the atomic gas chamber, the current introduced into the standard coil is changed in real time by keeping the background magnetic field unchanged as a judgment condition, and the magnetic moment of the magnetic sample is equal to the magnetic moment of the current-carrying standard coil; the directions are opposite.

Description

Technical Field

[0001] The present invention belongs to the field of precision measurement, and in particular relates to a magnetic moment comparator device and a measurement method. Background Art

[0002] In electromagnetism, the magnetic dipole layer and the current-carrying coil are equivalent, so the magnetic field generated by the magnetic sample in space can be equivalent to the magnetic field generated by the current-carrying coil on its axis. When the magnetic moments of the magnetic sample and the current-carrying coil are equal in magnitude, coincident in direction and opposite in direction, theoretically, the magnetic fields generated by the two at the midpoint of their distance cancel each other out. The present invention utilizes this feature to place a highly sensitive magnetic sensor at the midpoint of the distance between the magnetic sample and the current-carrying coil to form a magnetic moment comparator, thereby realizing the measurement of the magnetic moment of the magnetic sample using the magnetic moment of the current-carrying standard coil. Summary of the invention

[0003] In view of this, the present invention provides a magnetic moment comparator device and a measurement method, in which the current passed through the standard coil is changed in real time under the condition that the background magnetic field remains unchanged. The magnetic moment of the magnetic sample is equal to the magnetic moment of the current-carrying standard coil in magnitude but opposite in direction, so the magnetic moment of the magnetic sample is measured using the magnetic moment of the current-carrying standard coil.

[0004] Furthermore, in order to verify the validity of the magnetic moment comparator measurement method, the magnetic sample can be replaced by another current-carrying standard coil.

[0005] The magnetic moment comparator device of the present invention comprises a background magnetic field generating component, an atomic magnetometer for measuring absolute magnetic field, a first current-carrying standard coil component, a magnetic sample and a measuring module;

[0006] Wherein, the background magnetic field generating component includes a magnetic shielding coefficient better than 10 -3 A magnetic shielding tube and a background magnetic field coil placed inside the magnetic shielding tube; the magnetic shielding tube is used to achieve geomagnetic shielding, and the background magnetic field coil is used to generate a background magnetic field in the magnetic shielding tube. The background magnetic field is in the range of 200nT to 20000nT;

[0007] The atomic magnetometer is located in the magnetic shielding cylinder, and the direction of its circularly polarized pump light is parallel to the direction of the background magnetic field, and the direction of the linearly polarized detection light is perpendicular to the direction of the background magnetic field; the atomic magnetometer is used to measure the magnetic field of the space where the atomic gas chamber is located; the atomic magnetometer preferably adopts a pump-detection type rubidium atomic magnetometer, which has the characteristics of high sensitivity and wide range, and the range is 100nT to 100000nT;

[0008] The first current-carrying standard coil assembly includes a first standard coil and a first current source. The axis direction of the first standard coil is parallel to the background magnetic field. The first current source is used to pass current into the first standard coil. The output of the first current source is controlled by a measurement module. The measurement module can be set in an external computer and implemented using measurement software.

[0009] The magnetic moment direction of the magnetic sample is parallel to the background magnetic field direction, and the magnetic sample is moved into the magnetic shielding cylinder by using a sample transfer rod;

[0010] The first standard coil, the atomic gas chamber of the atomic magnetometer and the magnetic sample are placed on the symmetric center line of the background magnetic field coil in sequence. The distance between the first standard coil and the atomic gas chamber is equal to the distance between the magnetic sample and the atomic gas chamber. When the magnetic fields generated by the first standard coil and the magnetic sample at the position of the rubidium bubble are equal in magnitude and opposite in direction, the magnetic moment comparator reaches a state of equilibrium. According to this feature, the magnetic sample can be transferred to a position where the distance between it and the atomic gas chamber is equal to the distance between the first standard coil and the atomic gas chamber; the measurement module adjusts the current of the first standard coil so that the background magnetic field remains unchanged, the magnetic moment comparator reaches a state of equilibrium, the magnetic moment generated by the magnetic sample at the position of the atomic gas chamber is equal in magnitude and opposite in direction to the magnetic field generated by the first standard coil at the position of the atomic gas chamber, and the magnetic moment measurement result is obtained.

[0011] Preferably, the magnetic shielding tube has a diameter of φ500 mm and a length greater than or equal to 700 mm.

[0012] Preferably, the magnetic field gradient of the background magnetic field generated by the background magnetic field generating component is less than 1%.

[0013] Preferably, the size ratio of the first standard coil and the magnetic sample does not exceed 5 times.

[0014] Preferably, the device can also be used for verification. The magnetic sample can be replaced by a second current-carrying standard coil assembly consisting of a second standard coil and a second current source, the second current-carrying standard coil assembly can generate a magnetic moment to be measured, and the second standard coil and the first standard coil are set at an equal distance from the atomic gas chamber to verify the effectiveness of the magnetic moment comparator measurement method.

[0015] The present invention also provides a method for measuring magnetic moment, which uses the above-mentioned measuring device to perform measurement, comprising the following steps:

[0016] Step 1: Start the pump-detection rubidium atomic magnetometer, adjust the current passed into the background magnetic field coil according to the magnetic field value measured by the pump-detection rubidium atomic magnetometer, so that the background magnetic field is stabilized at a background magnetic field in the range of 200nT to 20000nT; set the distance between the first standard coil and the rubidium bubble to r 0 ;

[0017] Step 2: Use the sample transfer rod to move the magnetic sample into the magnetic shielding tube so that the distance between the magnetic sample and the rubidium bubble is r. 0 ; During the movement of the magnetic sample, the output current of the first current source is changed in real time by using the measurement module so that the background magnetic field remains unchanged;

[0018] Step 3: According to the expression Calculate the magnetic moment of the first standard coil, where n 1 ,I 1 and R 1 are the number of turns, current and radius of the first standard coil respectively; according to the fact that the magnetic moment of the magnetic sample is equal to the magnetic moment of the first standard coil and has the opposite direction, the magnetic moment of the magnetic sample can be obtained;

[0019] The method further comprises a verification process:

[0020] Step 4A: Replace the magnetic sample with a second current-carrying standard coil assembly consisting of a second standard coil and a second current source; set the distance between the second standard coil and the rubidium bubble to r 0 , using the second current source to pass current into the second standard coil to generate the magnetic moment to be measured; using the measurement module to change the output current of the first current source in real time to keep the background magnetic field unchanged;

[0021] Step 4B: Based on the expression and Calculate the magnetic moment of the first standard coil carrying current and the second standard coil carrying current respectively, where n 2 ,I 2 and R 2 are the number of turns, current and radius of the second standard coil respectively; through m 1 =m 2 Verify the effectiveness of the magnetic moment comparator measurement method.

[0022] Beneficial effects:

[0023] The present invention discloses a magnetic moment comparator device and a measuring method. The absolute magnetic field is measured with high sensitivity by using a pump-detection type rubidium atomic magnetometer. A current-carrying first standard coil and a magnetic sample are placed at equal distances on both sides of a rubidium bubble. The current passed through the first standard coil is changed in real time under the condition that the background magnetic field remains unchanged. The magnetic moment of the magnetic sample is measured by using the magnetic moment of the current-carrying first standard coil. In order to verify the effectiveness of the magnetic moment comparator measuring method, the magnetic sample is replaced by a current-carrying second standard coil, and the magnetic moment of the current-carrying second standard coil is measured by using the magnetic moment of the current-carrying first standard coil. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings are used to provide a further understanding of the technical solution of the present invention or the prior art, and constitute a part of the specification. Among them, the accompanying drawings expressing the embodiments of the present invention are used together with the embodiments of the present invention to explain the technical solution of the present invention, but do not constitute a limitation on the technical solution of the present invention.

[0025] Figure 1 It is a structural schematic diagram of a magnetic moment comparator device including a magnetic sample of the present invention;

[0026] Figure 2 is a structural schematic diagram of a magnetic moment comparator device including a second current source and a second standard coil provided in an embodiment of the present invention;

[0027] Figure 3 is a physical schematic diagram of a first standard coil provided in an embodiment of the present invention;

[0028] Figure 4 is a physical schematic diagram of a second standard coil provided in an embodiment of the present invention;

[0029] Figure 5 It is a schematic diagram of the magnetic field value output by a pump-detection type rubidium atomic magnetometer when the magnetic moment of a second standard coil is measured using a first standard coil provided by an embodiment of the present invention;

[0030] Figure 6 It is a schematic diagram of the current value output by the first current source when the magnetic moment of the second standard coil is measured by using the first standard coil provided by an embodiment of the present invention;

[0031] Figure numerals: 1 - magnetic shielding tube, 2 - background magnetic field coil, 3 - Helmholtz coil, 4 - rubidium bubble heating module, 5 - rubidium bubble, 6 - magnetic sample, 7 - sample transfer rod, 8 - first standard coil, 9 - first current source, 10 - circularly polarized pumping laser, 11 - linearly polarized detection laser, 12 - second standard coil, 13 - second current source. DETAILED DESCRIPTION

[0032] The following will describe the implementation methods of the present disclosure in detail with reference to the accompanying drawings and embodiments, so that the implementation process of how the present disclosure applies technical means to solve technical problems and achieve corresponding technical effects can be fully understood and implemented accordingly. The embodiments of the present disclosure and the various features in the embodiments can be combined with each other without conflict, and the technical solutions formed are all within the protection scope of the present disclosure.

[0033] Embodiment 1

[0034] Figure 1A schematic structural diagram of a magnetic moment comparator device including a magnetic sample according to a first embodiment of the present invention is shown. The device includes a magnetic shielding tube 1, a background magnetic field coil 2, a Helmholtz coil 3, a rubidium bubble heating module 4, a rubidium bubble 5, a magnetic sample 6, a sample transfer rod 7, a first standard coil 8, a first current source 9, a circularly polarized pumping laser 10, and a linearly polarized detection laser 11.

[0035] A magnetic moment comparator device includes a background magnetic field generating component, a pump-detection type rubidium atomic magnetometer, a first current-carrying standard coil component, a magnetic sample 6 and a measuring module;

[0036] The background magnetic field generating assembly includes a magnetic shielding tube 1 and a background magnetic field coil 2 placed inside the magnetic shielding tube 1; the magnetic shielding tube 1 is used to achieve geomagnetic shielding, and the background magnetic field coil 2 is used to generate a background magnetic field in the magnetic shielding tube 1; the background magnetic field is in the range of 200nT to 20000nT; this value needs to be within the range of various atomic magnetometers. The setting value of the background magnetic field should be designed in combination with the magnetic shielding tube to prevent the background magnetic field coil from magnetizing the magnetic shielding tube and causing drift of the measurement results.

[0037] In the embodiment, the magnetic shielding tube 1 is cylindrical, with a diameter of φ500 mm and a length greater than or equal to 700 mm. The background magnetic field is set to 500 nT, and the magnetic field gradient of the background magnetic field generated at the rubidium bubble position is less than 1%.

[0038] The composition and working principle of the pump-detection type rubidium atomic magnetometer are shown in the authorized invention patent "A rubidium atomic magnetometer and its magnetic field measurement method" (patent number: 201710270545.8). Figure 1 The pump-detection type rubidium atomic magnetometer only lists the Helmholtz coil 3, the rubidium bubble heating module 4, the rubidium bubble 5, the circularly polarized pumping laser 10 and the linearly polarized detection laser 11, and omits the components related to timing control, differential detection and data acquisition, wherein the Helmholtz coil 3, the rubidium bubble heating module 4 and the rubidium bubble 5 are placed in the magnetic shielding tube 1 of the background magnetic field generating component, and placed in the magnetic field uniformity area of ​​the background magnetic field coil 2; the direction of the circularly polarized pumping light is parallel to the direction of the background magnetic field, and the direction of the linearly polarized detection light is perpendicular to the direction of the background magnetic field; the pump-detection type rubidium atomic magnetometer is used to measure the magnetic field of the spatial position of the rubidium bubble 5 in the pump-detection type rubidium atomic magnetometer; the range of the pump-detection type rubidium atomic magnetometer is 100nT to 100000nT.

[0039] The first current-carrying standard coil assembly includes a first standard coil 8 and a first current source 9. The axial direction of the first standard coil 8 is parallel to the background magnetic field. The first current source 9 is used to pass current into the first standard coil 8. The output of the first current source 9 is controlled by a measurement module in a computer. In the embodiment of the present invention, the first current source 9 adopts a B2912A precision current source from Keysight Technologies.

[0040] The magnetic moment direction of the magnetic sample 6 is parallel to the background magnetic field direction, and the magnetic sample 6 is moved into the magnetic shielding cylinder by using the sample transfer rod 7;

[0041] The first standard coil 8, the rubidium bubble 5 and the magnetic sample 6 are placed on the axis of the background magnetic field coil 2 in sequence. The distance between the first standard coil 8 and the rubidium bubble 5 is equal to the distance between the magnetic sample 6 and the rubidium bubble 5. To meet this condition, the size ratio of the first standard coil 8 and the magnetic sample 6 should not exceed 5 times; when the magnetic fields generated by the current-carrying first standard coil 8 and the magnetic sample 6 at the position of the rubidium bubble 5 are equal in magnitude and opposite in direction, the magnetic moment comparator reaches a state of equilibrium. Utilizing this feature, the magnetic sample can be transferred to a position where the distance between it and the rubidium bubble 5 is equal to the distance between the first standard coil and the rubidium bubble 5; the measurement module adjusts the current of the first standard coil so that the background magnetic field remains unchanged, the magnetic moment comparator reaches a state of equilibrium, the magnetic field generated by the magnetic sample at the position of the rubidium bubble 5 is equal in magnitude and opposite in direction to the magnetic field generated by the first standard coil at the position of the rubidium bubble 5, and the magnetic moment measurement result is obtained.

[0042] This embodiment specifically describes a method for measuring magnetic moment using a magnetic moment comparator device, the method comprising the following steps:

[0043] Step 1: Start the pump-detection rubidium atomic magnetometer, adjust the current passed into the background magnetic field coil according to the magnetic field value measured by the pump-detection rubidium atomic magnetometer, and set the background magnetic field to 500nT; set the distance between the first standard coil and the rubidium bubble to r 0 is 20cm.

[0044] Step 2A: Use the sample transfer rod to move the magnetic sample into the magnetic shielding tube so that the distance between the magnetic sample and the rubidium bubble is r. 0 During the movement of the magnetic sample, the output current of the first current source is changed in real time using the measurement module to keep the background magnetic field unchanged.

[0045] Step 2B: According to the expression m 1 =n 1 I 1 πR 1 2 Calculate the magnetic moment of the first standard coil, where n 1 ,I 1 and R 1 are the number of turns, current and radius of the first standard coil respectively; according to the fact that the magnetic moment of the magnetic sample is equal to the magnetic moment of the current-carrying first standard coil but opposite in direction, the magnetic moment of the magnetic sample can be obtained.

[0046] Embodiment 2

[0047] In order to verify the effectiveness of the magnetic moment comparator measurement method, the magnetic sample is replaced by the second standard coil in the embodiment of the present invention, and an experiment is designed to measure the magnetic moment of the second standard coil using the magnetic moment of the first standard coil carrying current. The schematic diagram of the experimental device structure is shown in FIG. Figure 2 As shown, the distance between the first standard coil 8 and the rubidium bulb 5 is set to 20 cm, and the distance between the second standard coil 12 and the rubidium bulb 5 is also set to 20 cm; the first standard coil 8 and the second standard coil 12 are both made of a single layer of copper wire with a diameter of 0.45 mm wound on a glass tube with a diameter of 11 mm, and their coil turns are 30 turns and 15 turns respectively; the second current source 13 adopts the B2962A precision current source of Keysight Technologies.

[0048] This embodiment specifically describes the verification process of the above measurement scheme using a magnetic moment comparator device.

[0049] Specifically include:

[0050] Step 1: Start the pump-detection rubidium atomic magnetometer, adjust the current passed into the background magnetic field coil 2 according to the magnetic field value measured by the pump-detection rubidium atomic magnetometer, so that the background magnetic field is stabilized at a background magnetic field in the range of 200nT to 20000nT; set the distance between the first standard coil 8 and the second standard coil 12 and the rubidium bubble 5 to r 0 .

[0051] In one example, the distance between the second standard coil 12 and the rubidium bulb 5 can be set to r 0 is 20cm.

[0052] Step 2: Use the second current source 13 to pass current into the second standard coil 12 to generate the magnetic moment to be measured; use the measurement module to change the output current of the first current source 9 in real time to keep the background magnetic field unchanged.

[0053] In this step, the second current source 13 can be used to sequentially pass 100mA, 200mA, 300mA...1000mA currents for 60 seconds into the second standard coil 12 to sequentially generate a series of magnetic moments to be measured. The direction of the magnetic field generated by the current-carrying second standard coil 12 at the position of the rubidium bubble 5 is opposite to the direction of the background magnetic field. The output current of the first current source 9 is changed in real time using the measurement module to keep the background magnetic field unchanged.

[0054] When the magnetic moment of the second current-carrying standard coil 12 is measured by the first current-carrying standard coil 8, the magnetic field value output by the pump-detection type rubidium atomic magnetometer is as follows: Figure 5As shown, when the current passed through the second standard coil 12 increases, the pump-detection type rubidium atomic magnetometer measures that the magnetic field at the position of the rubidium bubble 5 decreases. The measurement software changes the output current of the first current source 9 in real time according to the measurement results of the pump-detection type rubidium atomic magnetometer to restore the background magnetic field to 500nT.

[0055] Step 3: Based on the expression and Calculate the magnetic moments of the first standard coil 8 and the second standard coil 12 respectively, where n 1 ,I 1 and R 1 are the number of turns, current and radius of the first standard coil 8, n 2 ,I 2 and R 2 are the number of turns, current and radius of the second standard coil 12; 1 =m 2 Verify the effectiveness of the magnetic moment comparator measurement method.

[0056] When the magnetic moment of the second standard coil 12 is measured by the first standard coil 8, the current value output by the first current source 9 is as follows: Figure 6 As shown, when the second current source 13 sequentially supplies currents of 100mA, 200mA, 300mA, 400mA, 500mA, 600mA, 700mA, 800mA, 900mA and 1000mA to the second standard coil 12, in order to keep the background magnetic field stable at 500nT, the average values ​​of the currents supplied by the first current source 9 to the first standard coil 8 are 50.2mA, 100.7mA, 151.2mA, 201.8mA, 252.1mA, 302.3mA, 352.5mA, 402.5mA, 452.4mA and 502.2mA, respectively. According to the expression m 1 =n 1 I 1 πR 1 2 Calculate, n 1 is 30, R 1 is 0.0055m, and the experimental values ​​of the magnetic moment of the first standard coil 8 carrying current are 0.143×10 -3 A.m 2 , 0.287×10 -3 A.m 2 , 0.431×10 -3 A.m 2 , 0.575×10 -3 A.m 2 , 0.719×10 -3 A.m 2 , 0.862×10 -3A.m 2 , 1.005×10 -3 A.m 2 , 1.148×10 -3 A.m 2 , 1.290×10 -3 A.m 2 and 1.432×10 -3 A.m 2 According to the expression Calculate, n 2 is 15, R 2 is 0.0055m, and the theoretical value of the magnetic moment of the second standard coil 12 is 0.143×10 -3 A.m 2 , 0.285×10 -3 A.m 2 , 0.428×10 -3 A.m 2 , 0.570×10 -3 A.m 2 , 0.713×10 -3 A.m 2 , 0.855×10 -3 A.m 2 , 0.998×10 -3 A.m 2 , 1.140×10 -3 A.m 2 , 1.283×10 -3 A.m 2 and 1.425×10 - 3 A.m 2 According to m 1 =m 2 The results of calculating "(experimental value-theoretical value) / theoretical value" of the current-carrying second standard coil 12 are all less than 1%, indicating that the magnetic moment comparator device and measurement method of the present invention are effective.

[0057] In summary, the embodiments are only preferred embodiments of the present disclosure and are not intended to limit the protection scope of the present disclosure. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

1. A magnetic moment comparator device, characterized in that: The device comprises a background magnetic field generating component, an atomic magnetometer for measuring absolute magnetic field, a first current-carrying standard coil component, a magnetic sample (6) and a measuring module; Wherein, the background magnetic field generating component includes a magnetic shielding coefficient better than 10 -3 A magnetic shielding cylinder (1) and a background magnetic field coil (2) disposed inside the magnetic shielding cylinder (1); the magnetic shielding cylinder (1) is used to achieve geomagnetic shielding, and the background magnetic field coil (2) is used to generate a background magnetic field in the magnetic shielding cylinder (1); The atomic magnetometer is located in a magnetic shielding cylinder (1), the direction of its circularly polarized pumping light is parallel to the direction of the background magnetic field, and the direction of its linearly polarized detection light is perpendicular to the direction of the background magnetic field; the atomic magnetometer is used to measure the magnetic field at the spatial position of the atomic gas chamber; The first current-carrying standard coil assembly comprises a first standard coil (8) and a first current source (9), the axis direction of the first standard coil (8) is parallel to the background magnetic field, the first current source (9) is used to pass current into the first standard coil (8), and the output of the first current source (9) is controlled by a measurement module; The magnetic moment direction of the magnetic sample (6) is parallel to the background magnetic field direction, and the magnetic sample (6) is moved into the magnetic shielding cylinder by using a sample transfer rod (7); The first standard coil (8), the atomic gas chamber of the atomic magnetometer and the magnetic sample (6) are placed in sequence on the symmetric center line of the background magnetic field coil (2), and the magnetic sample (6) is transferred to a position where the distance between the magnetic sample (6) and the atomic gas chamber is equal to the distance between the first standard coil (8) and the atomic gas chamber; the measurement module adjusts the current of the first standard coil (8) so that the background magnetic field remains unchanged, the magnetic moment comparator reaches a balanced state, and the magnetic moment generated by the magnetic sample (6) at the atomic gas chamber position is equal in magnitude and opposite in direction to the magnetic field generated by the first standard coil (8) at the atomic gas chamber position.

2. The magnetic moment comparator device according to claim 1, characterized in that: The atomic magnetometer for measuring absolute magnetic field adopts a pump-detection type rubidium atomic magnetometer to measure the magnetic field of a rubidium bubble (5) in the pump-detection type rubidium atomic magnetometer; the first standard coil (8), the rubidium bubble (5) in the pump-detection type rubidium atomic magnetometer and the magnetic sample (6) are placed on the axis of the background magnetic field coil (2) in sequence; the measurement range of the pump-detection type rubidium atomic magnetometer is 100nT to 100000nT, and the background magnetic field is in the range of 200nT to 20000nT.

3. The magnetic moment comparator device according to claim 2, characterized in that: The magnetic shielding tube (1) has a diameter of φ500 mm and a length greater than or equal to 700 mm.

4. The magnetic moment comparator device according to claim 2, characterized in that: The magnetic field gradient of the background magnetic field generated by the background magnetic field generating component is less than 1%.

5. The magnetic moment comparator device according to claim 2, characterized in that: The size ratio of the first standard coil (8) and the magnetic sample (6) does not exceed 5 times.

6. The magnetic moment comparator device according to claim 2, characterized in that: The magnetic sample (6) is replaced by a second current-carrying standard coil assembly consisting of a second standard coil (12) and a second current source (13), wherein the second current-carrying standard coil assembly is capable of generating a magnetic moment to be measured, and the second standard coil and the first standard coil are set at an equal distance from the atomic gas chamber, so as to verify the effectiveness of the magnetic moment comparator measurement method.

7. A measurement method based on a magnetic moment comparator, characterized in that: The method is applied to a magnetic moment comparator device according to any one of claims 2 to 6, and the method comprises: Step 1, starting the pump-detection type rubidium atomic magnetometer, adjusting the current passed into the background magnetic field coil (2) according to the magnetic field value measured by the pump-detection type rubidium atomic magnetometer, so that the background magnetic field is stabilized at a background magnetic field within the range of 200nT to 20000nT; setting the distance between the first standard coil (8) and the rubidium bubble (5) to r0; Step 2: using a sample transfer rod (7) to move the magnetic sample (6) into the magnetic shielding tube so that the distance between the magnetic sample (6) and the rubidium bubble (5) is r0; during the movement of the magnetic sample (6), using a measurement module to change the output current of the first current source (9) in real time so that the background magnetic field remains unchanged; Step 3: According to the expression m1=n1I1πR1 2 The magnetic moment of the first standard coil (8) is calculated, wherein n1, I1 and R1 are the number of turns, current and radius of the first standard coil (8) respectively; based on the fact that the magnetic moment of the magnetic sample (6) is equal in magnitude to the magnetic moment of the first standard coil (8) but opposite in direction, the magnetic moment of the magnetic sample (6) is obtained.

8. The method according to claim 7, characterized in that The method further comprises a verification process: Step 4A: replacing the magnetic sample (6) with a second current-carrying standard coil assembly consisting of a second standard coil (12) and a second current source (13); the second standard coil (12) is arranged at a position where the distance between the second standard coil (12) and the rubidium bulb (5) is r0, and current is supplied to the second standard coil (12) by using the second current source (13) to generate a magnetic moment to be measured; and the output current of the first current source (9) is changed in real time by using a measurement module to keep the background magnetic field unchanged; Step 4B: Based on the expression and The magnetic moments of the first standard coil (8) and the second standard coil (12) are calculated respectively, wherein n2, I2 and R2 are the number of turns, current and radius of the second standard coil (12) respectively; and the validity of the magnetic moment comparator measurement method is verified by m1=m2.

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