A geomagnetic field vector observation device and its adjustment method, and magnetic declination measurement method

Abstract

The present invention discloses a geomagnetic field vector observation device, an adjustment method thereof, and a magnetic declination measurement method. The stability of the spherical coil mechanism is ensured by suspending the spherical coil mechanism and using a Helmholtz coil clock. A slight tilt of the observation pier only has a small effect on the up and down posture of the Helmholtz coil axis, and does not cause rotation around the vertical axis. When the posture of the spherical coil mechanism remains unchanged, the effect on the magnetic declination measurement is extremely small and can be ignored, thereby improving the stability of the declination measurement. The spherical coil mechanism adopts a densely wound spherical coil with the characteristics of small size and large uniform space. The spherical coil mechanism is installed in the Helmholtz coil, so that after the posture of the suspended spherical coil mechanism is adjusted, it can still completely cover the uniform magnetic field space generated by the Helmholtz coil of the clock. A method of connecting the coils in multiple controllable modes is adopted to realize the measurement of three components of the geomagnetic field with a set of current sources.

Description

Technical Field

[0001] The present invention relates to a geomagnetic field vector observation device, in particular to a geomagnetic field vector observation device and an adjustment method thereof, and a magnetic declination measurement method. Background Art

[0002] Geomagnetic vector observations can consist of a scalar magnetometer and a geomagnetic field vector observation device. The horizontal component H is measured using an artificial compensation magnetic field, and the relative magnetic declination D is obtained using the artificial compensation magnetic field and positive and negative artificial bias magnetic fields in the east-west direction. The component coil system of this type of geomagnetic vector observation instrument is typically mounted on the observation pier in a clock-like configuration. During long-term observations, slight tilts in the pier can cause changes in the component coil attitude, which can easily lead to component measurement drift and significantly affect the observation results. Current solutions include using two sets of Helmholtz coil suspensions or two sets of spherical coil suspensions. In practice, these solutions reduce the drift of horizontal component observation data introduced by the pier tilt. However, the suspension can cause instability in the vertical rotation direction of the component coils with the east-west axis. This can also significantly affect the declination measurement under conditions such as shrapnel stress, external vibration, and airflow disturbances. Furthermore, traditional methods for measuring declination require two current sources: one for bias current and the other for compensation current, which increases the cost of the current sources. Summary of the Invention

[0003] Purpose of the invention: To provide a geomagnetic field vector observation device and its adjustment method, as well as a magnetic declination measurement method, to improve the stability of geomagnetic component measurement and reduce the current source of component measurement.

[0004] Technical solution: The geomagnetic field vector observation device of the present invention comprises: a foot adjustment mechanism, a non-magnetic turntable mechanism, a Helmholtz coil, a suspension mechanism, a spherical coil mechanism, a magnetic probe bracket mechanism, and a switching control circuit;

[0005] A foot adjustment mechanism is provided on the non-magnetic turntable mechanism, and the foot adjustment mechanism adjusts the vertical state of the rotation axis of the non-magnetic turntable mechanism; the axis of the Helmholtz coil is adjustably mounted on the non-magnetic turntable mechanism, and the suspension mechanism is mounted on the top of the Helmholtz coil; the spherical coil mechanism is suspended at the bottom of the suspension mechanism and is located within the Helmholtz coil, and the posture of the spherical coil mechanism is adjustable; the top of the magnetic probe bracket mechanism passes through the non-magnetic turntable mechanism and extends into the spherical coil mechanism, and an optically pumped magnetic sensor is installed at the top of the magnetic probe bracket mechanism in an angle-adjustable manner; a switching control circuit is electrically connected to the Helmholtz coil and the spherical coil mechanism, and the switching control circuit switches the series connection mode of the Helmholtz coil and the spherical coil mechanism.

[0006] Furthermore, the non-magnetic turntable mechanism includes a turntable, a base, an adjustment shaft, a leveler and an attitude adjustment screw; the adjustment shaft is rotatably mounted on the base, and the leveler is adjustably mounted on the adjustment shaft; the turntable is mounted on the upper side of the adjustment shaft; and the Helmholtz coil is mounted on the turntable through the attitude adjustment screw.

[0007] Furthermore, the foot adjustment mechanism includes three foot adjustment units; the foot adjustment unit includes a pad, a foot screw, a tapered external threaded sleeve and a tapered internal threaded tube; a mounting hole is provided on the base, and the bottom section of the mounting hole is a tapered section; both ends of the tapered internal threaded tube are tapered structures, and two notches are provided at both ends; the tapered internal threaded tube is provided in the mounting hole, and the bottom is inserted in the tapered section; the tapered external threaded sleeve is threadedly installed in the mounting hole, and the top of the tapered internal threaded tube is located in the tapered external threaded sleeve; the foot screw is threadedly matched with the tapered internal threaded tube, and the bottom end is supported on the pad.

[0008] Furthermore, the suspension mechanism includes an upper suspension plate, a middle suspension plate, a lower suspension plate and four carbon fiber springs; the upper suspension plate is installed on the top of the Helmholtz coil, the lower suspension plate is installed on the spherical coil mechanism, and the middle suspension plate is located between the upper suspension plate and the lower suspension plate; the two upper carbon fiber springs are arranged between the upper suspension plate and the middle suspension plate, and the two lower carbon fiber springs are arranged between the middle suspension plate and the lower suspension plate, and the two upper carbon fiber springs and the two lower carbon fiber springs are distributed in a cross shape up and down.

[0009] Furthermore, the spherical coil mechanism includes a spherical coil bracket, an upper hemisphere coil, a lower hemisphere coil, a counterweight locking nut and four coil counterweight units; the coil counterweight unit includes a counterweight rod and multiple counterweight nuts with different thickness specifications; the upper hemisphere coil and the lower hemisphere coil are both installed on the spherical coil bracket to form a spherical coil; a damping box is provided on the non-magnetic turntable mechanism; the counterweight locking nut is threadedly installed at the bottom of the spherical coil bracket, and the bottom of the counterweight locking nut extends into the damping box; the counterweight rod is installed on the outside of the counterweight locking nut, and multiple counterweight nuts are detachably installed on the corresponding counterweight rod.

[0010] Furthermore, the magnetic probe bracket mechanism includes a spherical magnetic probe bracket, an inner spherical magnetic probe bracket, a bracket locking block, a bracket rod and a bracket seat; the bottom end of the bracket rod is threadedly installed on the bracket seat, and the top end passes through the non-magnetic turntable mechanism and the damping box to extend into the spherical coil bracket and is threadedly installed on the inner spherical magnetic probe bracket; the spherical magnetic probe bracket is angle-adjustably installed in the inner spherical magnetic probe bracket, and is locked to the inner spherical magnetic probe bracket by the bracket locking block; a cylindrical hole is provided on the spherical magnetic probe bracket, and an optical pump magnetic sensor is installed in the cylindrical hole.

[0011] Furthermore, the switching control circuit includes a switching circuit, a current source and a controller; the switching circuit includes a relay K1, a relay K2 and a relay K3; the D1 end of the current source is electrically connected to the S1 end of the spherical coil mechanism, and the S2 end of the spherical coil mechanism is electrically connected to the moving contact of the relay K1, a fixed contact of K2 and a fixed contact of K3 respectively; the fixed contact of the relay K1 is electrically connected to the D2 end of the current source, another fixed contact of the relay K2 and another fixed contact of the relay K3 respectively; a moving contact of the relay K2 is electrically connected to the B1 end of the Helmholtz coil and a moving contact of the relay K3 respectively, and the other moving contact of the relay K2 is electrically connected to the B2 end of the Helmholtz coil and another moving contact of the relay K3 respectively; the controller is used to control the on and off of the coils of the relay K1, relay K2 and relay K3 respectively.

[0012] The present invention also provides a method for adjusting a geomagnetic field vector observation device, comprising the following steps:

[0013] Step 1: Install the non-magnetic turntable mechanism, set the foot adjustment mechanism and the bracket of the magnetic probe bracket mechanism on the observation pier and place them in the middle of the observation pier;

[0014] Step 2: Adjust the non-magnetic turntable mechanism so that the rotation axis of the Helmholtz coil is in a vertical state;

[0015] Step 3. Given a compensation current, use the compass for orientation, rotate the turntable of the non-magnetic turntable mechanism to adjust the four counterweight rods of the spherical coil mechanism to the east, west, south and north directions. First, measure the current orientation angle as the first horizontal component value, rotate the turntable 180 degrees, and then measure the current orientation angle as the second horizontal component value. The difference between the first horizontal component value and the second horizontal component value is the horizontal component steering difference. Adjust the counterweight nuts of the two spherical coil mechanisms in the north-south directions so that the horizontal component steering difference is less than 5nT. Then rotate the turntable 90 degrees, measure the horizontal component steering difference in the current direction, and adjust the two counterweight nuts in the current north-south directions so that the horizontal component steering difference is less than 5nT.

[0016] Step 4: Rotate the turntable to any angle and determine whether the current horizontal component steering difference is less than 5nT. If it is less than 5nT, proceed to the next step. If it is greater than or equal to 5nT, return to step 3.

[0017] Step 5: Orient the Helmholtz coil with the compass, set the axis of the Helmholtz coil in the magnetic east-west direction, and fine-tune the orientation angle by the turntable, so that the measured synthetic magnetic field R + and R -Equal, at this time the axis of the Helmholtz coil is the magnetic east-west direction, measure the horizontal component H1 and the horizontal component steering difference ΔH1 under the current direction, and then calculate the horizontal component value H=H1-ΔH1 / 2, and then calculate the vertical component based on the measured total magnetic field F

[0018] Step 6: Rotate the turntable of the non-magnetic turntable mechanism by 90 degrees. Set the Helmholtz coil axially in the magnetic north-south direction. Use the compensation method to measure the vertical component of the geomagnetic field. The compensation current of the vertical component of the geomagnetic field is set to H / K. h , use the attitude adjustment screw of the non-magnetic turntable mechanism to adjust the attitude of the Helmholtz coil so that the measured vertical component is equal to the calculated vertical component, and then turn the turntable back to the initial angle of this step.

[0019] Step 7, reselect a compensation current for the horizontal component, rotate the turntable to any direction, and determine whether the current horizontal component steering difference should be less than 5nT. If it is less than 5nT, the adjustment of the observation device is completed, otherwise repeat steps 3-6.

[0020] The present invention also provides a method for measuring magnetic declination of a geomagnetic field vector observation device, comprising the following steps:

[0021] Step A, measure the initial direction N of the magnetic declination m :The controller of the switching control circuit controls relays K1, K2, and K3 to be disconnected, and the axis of the spherical coil mechanism is adjusted to be vertically downward, and the axis of the Helmholtz coil points to the magnetic east-west direction. The optical pump magnetic sensor measures the initial total magnetic field F0. The initial total magnetic field F0 can be decomposed into an initial horizontal component H0 on the horizontal plane and an initial vertical component Z0 perpendicular to the horizontal plane. At this time, the direction of the initial horizontal component H0 is the initial direction N of the magnetic declination. m ;

[0022] Step B, measuring the horizontal component H and the vertical component Z: the controller of the switching control circuit controls relay K1 to close, relay K2 and relay K3 to open, and sets the current source current to I h The total magnetic field F is measured by the optically pumped magnetic sensor. The total magnetic field F can be decomposed into a horizontal component H on the horizontal plane and a vertical component Z perpendicular to the horizontal plane. At this time, the horizontal component H is related to the initial direction N of the magnetic declination. m The angle between them is θ;

[0023] Step C, measure the biased synthetic magnetic field R + :The controller of the switching control circuit controls relay K2 to close, relay K1 and relay K3 are all disconnected, and the coil constant of the spherical coil is K s , the coil constant of the Helmholtz coil is K h, the spherical coil and the Helmholtz coil pass through the current I at the same time h At this time, a compensation magnetic field C1 is generated, and I h K s = Z1 = Z, and is opposite to the vertical component Z; then the composite magnetic field R of the compensating magnetic field C1 and the total magnetic field F + On the horizontal plane, the projection of the compensation magnetic field C1 on the horizontal component H is C 1h =I h K h , then:

[0024]

[0025] have to:

[0026] Step D, measuring the biased synthetic magnetic field R_: the controller of the switching control circuit controls relay K3 to close, relays K1 and K2 to open, and current I flows through the spherical coil and the Helmholtz coil at the same time. h , at this time, a compensation magnetic field C2 is generated, and I h K s = Z2 = Z, and is opposite to the vertical component Z; then the composite magnetic field R_ of the compensation magnetic field C2 and the total magnetic field F is on the horizontal plane, and the projection of the compensation magnetic field C2 on the horizontal component H is C 2h =I h K h , then:

[0027]

[0028] have to:

[0029] Step E: From equations (2) and (4), we can get:

[0030]

[0031] Then measure the initial direction N of the magnetic declination m The angle with the geographic north direction is D0,

[0032] Then, the magnetic declination D=D0+θ.

[0033] Compared with the prior art, the present invention has the following advantages: by adopting a spherical coil mechanism suspension and a Helmholtz coil clock, the stability of the spherical coil mechanism is ensured, so that a slight tilt of the observation pier has only a small impact on the up and down posture of the Helmholtz coil axis and does not cause rotation around the vertical axis. When the posture of the spherical coil mechanism remains unchanged, the impact on the magnetic declination measurement is extremely small and can be ignored, thereby improving the stability of the declination measurement. The spherical coil mechanism adopts a densely wound spherical coil with the characteristics of small size and large uniform space. The spherical coil mechanism is installed in the Helmholtz coil, so that after the posture of the suspended spherical coil mechanism is adjusted, it can still completely cover the uniform magnetic field space generated by the Helmholtz coil of the clock. A method of connecting the coils in series in multiple controllable modes is adopted to achieve the measurement of three components of the geomagnetic field with a set of current sources. The suspension mechanism uses the Helmholtz coil as a bracket, and the overall structure is more compact. The magnetic probe bracket mechanism has a structure that can adjust the probe posture over a wide range, adapting to the operation of sensors such as optically pumped magnetometers in different regions to avoid measurement dead zones when measuring each component. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is the main view of the geomagnetic field vector observation device;

[0035] Figure 2 This is the right view of the geomagnetic field vector observation device;

[0036] Figure 3 This is the main cross-sectional view of the geomagnetic field vector observation device;

[0037] Figure 4 This is a right sectional view of the geomagnetic field vector observation device;

[0038] Figure 5 This is a schematic diagram of the tapered internal threaded tube structure of the geomagnetic field vector observation device;

[0039] Figure 6 This is a schematic diagram of the structure of the foot adjustment mechanism of the geomagnetic field vector observation device;

[0040] Figure 7 This is a switching control circuit diagram of a geomagnetic field vector observation device;

[0041] Figure 8 This is a schematic diagram of the magnetic declination of the geomagnetic field vector observation device;

[0042] Figure 9 This is a schematic diagram of the influence of the attitude tilt of the Helmholtz coil of the geomagnetic field vector observation device;

[0043] Figure 10 This is a schematic diagram of the influence of the attitude tilt of the Helmholtz coil of the geomagnetic field vector observation device;

[0044] Figure 11This is a schematic diagram of the influence of the attitude tilt of the Helmholtz coil of the geomagnetic field vector observation device. DETAILED DESCRIPTION

[0045] The technical solution of the present invention is described in detail below with reference to the accompanying drawings, but the protection scope of the present invention is not limited to the embodiments.

[0046] Example 1:

[0047] like Figure 1-11 As shown, the geomagnetic field vector observation device disclosed in the present invention includes: a base adjustment mechanism, a non-magnetic turntable mechanism, a Helmholtz coil 9, a suspension mechanism, a spherical coil mechanism, a magnetic probe bracket mechanism and a switching control circuit;

[0048] The foot adjustment mechanism is arranged on the non-magnetic turntable mechanism, and the foot adjustment mechanism adjusts the vertical state of the rotation axis of the non-magnetic turntable mechanism; the axis of the Helmholtz coil 9 is adjustably installed on the non-magnetic turntable mechanism, and the suspension mechanism is installed on the top of the Helmholtz coil 9; the spherical coil mechanism is suspended at the bottom of the suspension mechanism and is located inside the Helmholtz coil 9, and the posture of the spherical coil mechanism is adjustable, and the spherical coil mechanism generates a larger magnetic uniform space, thereby covering the magnetic uniform space generated by the Helmholtz coil 9; the top of the magnetic probe bracket mechanism passes through the non-magnetic turntable mechanism and extends into the spherical coil mechanism, and an optical pump magnetic sensor is installed at the top of the magnetic probe bracket mechanism with an adjustable angle; the switching control circuit is electrically connected to the Helmholtz coil 9 and the spherical coil mechanism, and the switching control circuit switches the series connection mode of the Helmholtz coil 9 and the spherical coil mechanism.

[0049] By using a spherical coil mechanism suspension and a Helmholtz coil 9 table clock, the stability of the spherical coil mechanism is ensured, so that a slight tilt of the observation pier only has a small impact on the up and down posture of the axis of the Helmholtz coil 9, and does not cause rotation around the vertical axis. When the posture of the spherical coil mechanism remains unchanged, the impact on the magnetic declination measurement is extremely small and can be ignored, thereby improving the stability of the declination measurement. The spherical coil mechanism uses a densely wound spherical coil with the characteristics of small size and large uniform space. The spherical coil mechanism is installed in the Helmholtz coil 9, so that after the posture of the suspended spherical coil mechanism is adjusted, it can still completely cover the uniform magnetic field space generated by the table clock Helmholtz coil 9. The coil is controlled in multiple ways in series to realize the measurement of the three components of the geomagnetic field by a set of current sources. The suspension mechanism uses the Helmholtz coil 9 as a bracket, and the overall structure is more compact. The magnetic probe bracket mechanism has a structure that can adjust the probe posture over a wide range, which adapts to the operation of sensors such as optically pumped magnetometers in different regions to avoid measurement dead zones when measuring each component.

[0050] Furthermore, the non-magnetic turntable mechanism includes a turntable 5, a base 6, an adjusting shaft 7, a level 8 and a posture adjustment screw 10; the adjusting shaft 7 is rotatably mounted on the base 6, and a scale is evenly engraved on the top side of the adjusting shaft 7, a dial is mounted on the top side of the base 6, and both the scale and the dial adopt a differential structure with a resolution of 0.1 degree; the turntable 5 is mounted on the adjusting shaft 7, and the level 8 is adjustably mounted on the adjusting shaft 7, and an adjustment seat with a triangular structure is provided on one side of the level 8, a circular hole is provided on the adjusting seat, and a level adjustment screw is threaded through the circular hole; an adjustment plate is installed on the other side, a threaded hole and a light hole are provided on the adjustment plate, and a level adjustment screw is mounted through the threaded hole and the light hole The Helmholtz coil 9 is installed on the turntable 5 through the attitude adjustment screw 10, and the attitude adjustment screw 10 is used to adjust the axial attitude of the Helmholtz coil 9. A mounting groove and a fixing hole for installing the suspension mechanism are provided on the top of the Helmholtz coil 9, which is convenient for installing the suspension mechanism. The middle taps of the two coils in the Helmholtz coil 9 are directly connected, and the two end wires are led out to the controller, and the two terminals of the Helmholtz coil 9 are B1 and B2; the horizontality of the leveler 8 can be adjusted by the level adjustment screw, the level adjustment screw and the locking screw to achieve the effect of detecting the verticality of the rotating axis of the turntable 5, so that the rotating axis of the Helmholtz coil 9 installed on the turntable 5 is in a vertical state.

[0051] Furthermore, the foot adjustment mechanism includes three foot adjustment units; the foot adjustment unit includes a pad 1, a foot screw 2, a tapered externally threaded sleeve 3 and a tapered internally threaded tube 4; both ends of the tapered internally threaded tube 4 are tapered structures, and two notches are provided at both ends of the tapered internally threaded tube 4, and the notches at both ends are orthogonal, and a mounting hole is provided on the base 6 that passes through the top and the bottom, and the bottom section of the mounting hole is a tapered section that is wide at the top and narrow at the bottom; the tapered internally threaded tube 4 is arranged in the mounting hole, and the bottom is inserted in the tapered section, the tapered externally threaded sleeve 3 is threadedly installed in the mounting hole, and the top of the tapered internally threaded tube 4 is positioned In the tapered external threaded sleeve 3; the base screw 2 is threadedly matched with the tapered internal threaded tube 4, and the bottom end is supported on the pad 1; the height and level of the base 6 can be adjusted by the base screw 2 to adjust the level of the turntable 5. After the tapered external threaded sleeve 3 and the tapered internal threaded tube 4 are locked, the two ends of the tapered internal threaded tube 4 are set as tapered structures and orthogonal notches, so that the tapered external threaded sleeve 3 is squeezed toward one side of the tapered internal threaded tube 4, which can reduce the gap between the thread fits and improve stability. At the same time, the influence of the thread gap on the turntable 5 is avoided.

[0052] Furthermore, the suspension mechanism includes an upper suspension plate 11, a middle suspension plate 12, a lower suspension plate 13, four carbon fiber springs 14 and a plurality of mounting pressure blocks 15; the upper suspension plate 11 is installed on the top of the Helmholtz coil 9 through the mounting groove and the fixing hole, the lower suspension plate 13 is installed on the spherical coil mechanism, the middle suspension plate 12 is located between the upper suspension plate 11 and the lower suspension plate 13, the two upper carbon fiber springs 14 are arranged between the upper suspension plate 11 and the middle suspension plate 12 through the mounting pressure blocks 15, and the two lower carbon fiber springs 14 are arranged between the middle suspension plate 12 and the lower suspension plate 13 through the mounting pressure blocks 15, and the two upper carbon fiber springs 14 and the two lower carbon fiber springs 14 are distributed in a cross shape up and down, and each carbon fiber spring 14 is 0.3 mm thick; the spherical coil mechanism is suspended by the suspension mechanism, and since the two groups of carbon fiber springs 14 are distributed in a cross shape, the position of the spherical coil mechanism is conveniently adjusted.

[0053] Furthermore, the spherical coil mechanism includes a spherical coil bracket 16, an upper hemispherical coil 17, a lower hemispherical coil 18, a damping box 24 and four coil counterweight units; the coil counterweight unit includes a counterweight rod 22 and a plurality of counterweight nuts 23; the thickness specifications of the plurality of counterweight nuts 23 are different, and a card slot adapted to the spherical coil bracket 16 is provided on the upper hemispherical coil 17 and the lower hemispherical coil 18, and the upper hemispherical coil 17 and the lower hemispherical coil 18 are both installed on the spherical coil bracket 16 to form a spherical coil, the upper hemispherical coil 17 and The lower hemispherical coils 18 are all densely wound spherical coils with the advantages of small size and large uniform space, which can completely cover the magnetic uniform space generated by the Helmholtz coil 9. The upper hemispherical coils 17 and the lower hemispherical coils 18 are directly connected in the middle of the tap, and the two end wires are led out to the controller. The terminals of the spherical coils formed by the upper hemispherical coils 17 and the lower hemispherical coils 18 are S1 and S2. The lead wires are made of extremely soft wires near the spherical coils to avoid the lead wires affecting the posture of the spherical coil mechanism. A counterweight is installed on the bottom thread of the spherical coil bracket 16 to lock it. Nut 21, the counterweight locking nut 21 is made of non-magnetic brass, has a large weight, and can maintain coaxiality with the spherical coil bracket 16. The counterweight rod 22 is evenly distributed and installed on the outside of the counterweight locking nut 21. Multiple counterweight nuts 23 are detachably installed on the corresponding counterweight rod 22. The damping box 24 is fixed to the turntable 5 through the support plate, and the damping box 24 is a circular ring structure. A damping liquid is provided inside the damping box 24. The damping liquid is silicone oil, which has the advantages of small surface tension and non-volatile. A sleeve is installed on the upper side of the damping box 24. The bottom of the tube extends into the damping box 24 to prevent the damping fluid inside the damping box 24 from overflowing. A notch that matches the tube sleeve is provided on the bottom side of the counterweight locking nut 21, and the bottom of the counterweight locking nut 21 extends into the damping box 24. The posture of the spherical coil bracket 16 is adjusted by the counterweight rod 22 and the counterweight nut 23 to adjust the posture of the upper hemisphere coil 17 and the lower hemisphere coil 18. The counterweight locking nut 21 is placed in the damping fluid to facilitate rapid stabilization during the adjustment of the suspension mechanism and after disturbance.

[0054] Furthermore, the magnetic probe bracket mechanism includes a spherical magnetic probe bracket 26, an inner spherical magnetic probe bracket 27, a bracket locking pressure block 28, a bracket rod 30 and a bracket seat 31; the bottom end of the bracket rod 30 is threadedly installed on the bracket seat 31, and the top end non-contactly passes through the adjustment shaft 7 and the damping box 24 to extend into the spherical coil bracket 16 and is threadedly installed on the inner spherical magnetic probe bracket 27; a wire groove is provided on the bracket rod 30, and the spherical magnetic probe bracket 26 is installed in the inner spherical magnetic probe bracket 27 in an angle-adjustable manner, and the bracket locking pressure block 28 is fixed to the bracket locking screw The nail is locked with the inner spherical magnetic probe bracket 27, and a cylindrical hole for installing the optical pump magnetic sensor is provided on the spherical magnetic probe bracket 26, and the optical pump magnetic sensor is installed in the cylindrical hole through the probe locking screw 29; by installing the magnetic probe bracket mechanism and the spherical coil mechanism in a contactless manner, the spherical magnetic probe bracket 26 and the inner spherical magnetic probe bracket 27 are completely independent of the spherical coil mechanism. During the coil adjustment process of the spherical coil mechanism, the probe direction remains unchanged, and the probe lead wire can be led out through the wire groove to avoid the probe lead wire affecting the suspension mechanism.

[0055] Furthermore, the switching control circuit includes a switching circuit, a current source, and a controller; the switching circuit includes a relay K1, a relay K2, and a relay K3; the relay K1 is a single-pole relay, the relays K2 and K3 are double-pole relays, and the relays K2 and K3 are interlocked, the Helmholtz coil 9 and the spherical coil use the same set of current sources, and the current source input terminals are D1 and D2; the D1 terminal of the current source is electrically connected to the S1 terminal of the spherical coil mechanism, and the S2 terminal of the spherical coil mechanism is electrically connected to the moving contact of the relay K1, a fixed contact of K2, and a fixed contact of K3 respectively; the relay K1 The fixed contacts of relay K1, relay K2 and relay K3 are electrically connected to the D2 terminal of the current source, the other fixed contact of relay K2 and the other fixed contact of relay K3 respectively; one moving contact of relay K2 is electrically connected to the B1 terminal of the Helmholtz coil 9 and a moving contact of relay K3 respectively, and the other moving contact of relay K2 is electrically connected to the B2 terminal of the Helmholtz coil 9 and the other moving contact of relay K3 respectively; the controller is used to control the power on and off of the coils of relay K1, relay K2 and relay K3 respectively, and relay K1, relay K2 and relay K3 can all be replaced with electronic switches with faster speed and longer life.

[0056] The present invention provides a method for adjusting a geomagnetic field vector observation device, comprising the following steps:

[0057] Step 1: Install the non-magnetic turntable mechanism, set the foot adjustment mechanism and the bracket 31 of the magnetic probe bracket mechanism on the observation pier and place it in the middle of the observation pier;

[0058] Step 1.1: Place the connecting line of the two foot screws 2 of the foot adjustment mechanism in the magnetic north-south or east-west direction, align the center of the turntable 5 of the non-magnetic turntable mechanism and the center of the bracket 31 of the magnetic probe bracket mechanism with the center of the observation pier, and adjust the posture of the optical pump magnetic sensor so that the horizontal component, vertical component, total field, R + and R - Avoid the measurement dead zone of optically pumped magnetic sensors;

[0059] Step 1.2: Glue the pad 1 of the foot adjustment mechanism to the pier surface of the observation pier.

[0060] Step 2: Adjust the non-magnetic turntable mechanism so that the rotation axis of the Helmholtz coil 9 is in a vertical state;

[0061] Step 2.1: Rotate the level 8 of the non-magnetic turntable mechanism to the direction of the line connecting the two foot screws 2 of the foot adjustment mechanism, and rotate the foot screws 2 to adjust the bubble of the level 8 to the middle position;

[0062] Step 2.2, rotate the turntable 5 of the non-magnetic turntable mechanism 180°, adjust half of the bubble deviation with the level adjustment screw on one side of the level 8, and adjust the other half with the base screw 2;

[0063] Step 2.3, repeat steps 2.1 and 2.2 until the difference in the bubble reading on the level 8 in that direction does not exceed 0.2 grids;

[0064] Step 2.4, rotate the turntable 5 of the non-magnetic turntable mechanism 120 degrees, and repeat the above steps 2.1 and 2.2 until the bubble of the level 8 is in the middle position when the turntable table is rotated to any angle.

[0065] Step 3. Given a compensation current, use the compass for orientation, rotate the turntable 5 to adjust the four counterweight rods 22 of the spherical coil mechanism to the east, west, south and north directions. First, measure the current orientation angle as the first horizontal component value, rotate the turntable 5 180 degrees, and then measure the current orientation angle as the second horizontal component value. The difference between the first horizontal component value and the second horizontal component value is the horizontal component steering difference. Adjust the counterweight nuts 23 of the two spherical coil mechanisms in the north-south direction so that the horizontal component steering difference is less than 5nT. Then rotate the turntable 5 90 degrees, measure the horizontal component steering difference in the current direction, and adjust the two counterweight nuts 23 in the current north-south direction so that the horizontal component steering difference is less than 5nT.

[0066] Step 4: Rotate the turntable 5 to any angle and determine whether the current horizontal component steering difference is less than 5nT. If it is less than 5nT, proceed to the next step; if it is greater than or equal to 5nT, return to step 3.

[0067] Step 5: Orient the Helmholtz coil 9 in the magnetic east-west direction using the compass, and adjust the orientation angle by the turntable 5 so that the measured synthetic magnetic field R + and R - Equal, at this time the axial direction of the Helmholtz coil 9 is the magnetic east-west direction, the horizontal component H1 and the horizontal component steering difference ΔH1 under the current direction are measured, the horizontal component value is H=H1-ΔH1 / 2, and then the vertical component is calculated based on the measured total magnetic field F

[0068] Step 6: Rotate the turntable 5 of the non-magnetic turntable mechanism by 90 degrees so that the Helmholtz coil 9 is axially arranged in the magnetic north-south direction, and use the compensation method to measure the vertical component of the geomagnetic field, K h is the coil constant of the Helmholtz coil 9, and the compensation current of the vertical component of the geomagnetic field is set to H / K h , use the attitude adjustment screw 10 of the non-magnetic turntable mechanism to adjust the attitude of the Helmholtz coil 9 so that the measured vertical component is equal to the calculated vertical component, and then turn the turntable 5 back to the initial angle of this step.

[0069] Step 7, reselect a compensation current for the horizontal component, rotate the turntable 5 to any direction, and determine whether the current horizontal component steering difference should be less than 5nT. If it is less than 5nT, the adjustment of the observation device is completed, otherwise repeat steps 3-6.

[0070] The present invention also provides a method for measuring magnetic declination of a geomagnetic field vector observation device, comprising the following steps:

[0071] Step A, measure the initial direction N of the magnetic declination m :The controller of the switching control circuit controls relays K1, K2, and K3 to be disconnected, adjusts the axis of the spherical coil vertically downward, and the axis of the Helmholtz coil 9 points to the magnetic east-west direction. The optical pump magnetic sensor measures the initial total magnetic field F0. The initial total magnetic field F0 can be decomposed into an initial horizontal component H0 on the horizontal plane and an initial vertical component Z0 perpendicular to the horizontal plane. At this time, the direction of the initial horizontal component H0 is the initial direction N of the magnetic declination. m ;

[0072] Step B, measuring the horizontal component H and the vertical component Z: the controller of the switching control circuit controls relay K1 to close, relays K2 and K3 to open, and the classic Nelson method is used to obtain the compensation current I of the horizontal component H. h , will I hThe current set as the current source remains unchanged or remains unchanged within each measurement cycle. The current is tracked in real time after each measurement cycle. The total magnetic field F is measured by the optically pumped magnetic sensor. The total magnetic field F can be decomposed into a horizontal component H on the horizontal plane and a vertical component Z perpendicular to the horizontal plane. At this time, the horizontal component H is related to the initial direction N of the magnetic declination angle. m The angle between them is θ;

[0073] Step C, measure the biased synthetic magnetic field R + :The controller of the switching control circuit controls relay K2 to close, and relays K1 and K3 are all disconnected, so that the spherical coil and the Helmholtz coil 9 are connected in series. The coil constant of the spherical coil is K s , the coil constant of the Helmholtz coil 9 is K h , the spherical coil and the Helmholtz coil 9 pass current I at the same time h At this time, a compensation magnetic field C1 is generated, and I h K s = Z1 = Z, and is opposite to the vertical component Z; then the composite magnetic field R of the compensating magnetic field C1 and the total magnetic field F + On the horizontal plane, the projection of the compensation magnetic field C1 on the horizontal component H is C 1h =I h K h , then:

[0074]

[0075] have to:

[0076] Step D, measuring the biased synthetic magnetic field R_: the controller of the switching control circuit controls the relay K3 to be closed, and the relays K1 and K2 to be disconnected, so that the spherical coil and the Helmholtz coil 9 are connected in series in reverse, and the spherical coil and the Helmholtz coil 9 pass the current I at the same time. h , at this time, a compensation magnetic field C2 is generated, and I h K s = Z2 = Z, and is opposite to the vertical component Z; then the composite magnetic field R_ of the compensation magnetic field C2 and the total magnetic field F is on the horizontal plane, and the projection of the compensation magnetic field C2 on the horizontal component H is C 2h =I h K h , then:

[0077]

[0078] have to:

[0079] Step E: From equations (2) and (4), we can get:

[0080]

[0081] Then measure the initial direction N of the magnetic declination m The angle with the geographic north direction is D0,

[0082] Then, the magnetic declination D=D0+θ.

[0083] Since the coil constant K of the spherical coil s and the coil constant K of the Helmholtz coil 9 h , roughly consistent with K s / K h =Z / H, thus meeting the application requirements in different latitudes.

[0084] When the geomagnetic field vector observation device of the present invention is performing observations, the posture of the spherical coil remains unchanged. When the Helmholtz coil 9 is slightly tilted, the magnitude and direction of the compensation magnetic field are not affected, and therefore the horizontal component observation results are not affected. The specific verification method is as follows:

[0085] When the spherical coil posture remains unchanged, the Helmholtz coil 9 is perpendicular to the initial direction N of the magnetic declination. m When tilting ε2, it will not affect the bias magnetic field C + and C - The magnitude and direction of θ will not affect the observed results of the relative magnetic declination θ.

[0086] When the spherical coil posture remains unchanged, the Helmholtz coil 9 is along the initial direction N of the magnetic declination. m When tilted ε1, the artificial bias magnetic field C after tilting + ′ and C - The resultant magnetic field of ′ and the horizontal component H is R + ′ and R - ′, where the artificial bias magnetic field C + ′ and C - The projection of ′ on the horizontal plane is C + ″ and C - ″, synthetic magnetic field R + ′ and R - The projection of ′ on the horizontal plane is R + ″ and R - ″, the direction of the initial magnetic field H0′ after tilt is N m ′In the artificial bias magnetic field C + ′ and C - ′ and the horizontal component H, and the vertical artificial bias magnetic field C + and C - ′, horizontal component H and tilted magnetic field direction N m ′ is θ′,

[0087] According to the three cosine theorem: cosγ=cosα×cosβ,

[0088] And: α=ε1, γ=θ′+90, β=θ+90,

[0089] Then: cos(90+θ′)=cosε1×cos(90+θ),

[0090] sinθ′=cosε1×sinθ,

[0091] When θ and θ′ are both very small, we have: sin(θ′)≈θ′, sin(θ≈θ,

[0092] So we get:

[0093] θ′=θcosε1,

[0094] Then the Δθ introduced by the tilt change of the Helmholtz coil 9 is:

[0095] Δθ=θ-θ′,

[0096] Δθ=θ(1-cosε1),

[0097] When the instrument is working normally, ε1 is much smaller than 60′, and θ is usually not greater than 20′, then Δθ<0.003′,

[0098] Therefore, when the posture of the spherical coil remains unchanged and the Helmholtz coil 9 tilts slightly, the effect on the observation result is extremely small and can be ignored.

[0099] As described above, although the present invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the present invention itself. Various changes may be made to it in form and detail without departing from the spirit and scope of the present invention as defined in the appended claims.

Claims

1. A geomagnetic field vector observation device, characterized in that: It includes a foot adjustment mechanism, a non-magnetic turntable mechanism, a Helmholtz coil (9), a suspension mechanism, a spherical coil mechanism, a magnetic probe bracket mechanism, and a switching control circuit; The foot adjustment mechanism is arranged on the non-magnetic turntable mechanism, and the foot adjustment mechanism adjusts the vertical state of the rotation axis of the non-magnetic turntable mechanism; the axis of the Helmholtz coil (9) is adjustably mounted on the non-magnetic turntable mechanism, and the suspension mechanism is mounted on the top of the Helmholtz coil (9); the spherical coil mechanism is suspended at the bottom of the suspension mechanism and is located inside the Helmholtz coil (9), and the posture of the spherical coil mechanism is adjustable; the top of the magnetic probe bracket mechanism passes through the non-magnetic turntable mechanism and extends into the spherical coil mechanism, and an optical pump magnetic sensor is installed at the top of the magnetic probe bracket mechanism in an angle-adjustable manner; the switching control circuit is electrically connected to the Helmholtz coil (9) and the spherical coil mechanism, and the switching control circuit switches the series connection mode of the Helmholtz coil (9) and the spherical coil mechanism; The spherical coil mechanism comprises a spherical coil bracket (16), an upper hemisphere coil (17), a lower hemisphere coil (18), a counterweight locking nut (21) and four coil counterweight units; the coil counterweight unit comprises a counterweight rod (22) and a plurality of counterweight nuts (23) with different thickness specifications; the upper hemisphere coil (17) and the lower hemisphere coil (18) are both mounted on the spherical coil bracket (16) to form a spherical coil; a damping box (24) is provided on the non-magnetic turntable mechanism; the counterweight locking nut (21) is threadedly mounted on the bottom of the spherical coil bracket (16), and the bottom of the counterweight locking nut (21) extends into the damping box (24); the counterweight rod (22) is mounted on the outside of the counterweight locking nut (21), and a plurality of counterweight nuts (23) are detachably mounted on the corresponding counterweight rod (22).

2. The geomagnetic field vector observation device according to claim 1, characterized in that: The non-magnetic turntable mechanism comprises a turntable (5), a base (6), an adjusting shaft (7), a leveler (8) and an attitude adjustment screw (10); the adjusting shaft (7) is rotatably mounted on the base (6), and the leveler (8) is adjustably mounted on the adjusting shaft (7); the turntable (5) is mounted on the upper side of the adjusting shaft (7); and the Helmholtz coil (9) is mounted on the turntable (5) via the attitude adjustment screw (10).

3. The geomagnetic field vector observation device according to claim 2, characterized in that: The foot adjustment mechanism comprises three foot adjustment units; the foot adjustment unit comprises a pad (1), a foot screw (2), a tapered external threaded sleeve (3) and a tapered internal threaded tube (4); a mounting hole is provided on the base (6), and the bottom section of the mounting hole is a tapered section; both ends of the tapered internal threaded tube (4) are tapered structures, and two notches are provided at both ends; the tapered internal threaded tube (4) is provided in the mounting hole, and the bottom is inserted into the tapered section; the tapered external threaded sleeve (3) is threadedly installed in the mounting hole, and the top of the tapered internal threaded sleeve (4) is located in the tapered internal threaded sleeve (3); the foot screw (2) is threadedly matched with the tapered internal threaded tube (4), and the bottom end is supported on the pad (1).

4. The geomagnetic field vector observation device according to claim 1, characterized in that: The suspension mechanism comprises an upper suspension plate (11), a middle suspension plate (12), a lower suspension plate (13) and four carbon fiber springs (14); the upper suspension plate (11) is mounted on the top of the Helmholtz coil (9), the lower suspension plate (13) is mounted on the spherical coil mechanism, and the middle suspension plate (12) is located between the upper suspension plate (11) and the lower suspension plate (13); the two upper carbon fiber springs (14) are arranged between the upper suspension plate (11) and the middle suspension plate (12), and the two lower carbon fiber springs (14) are arranged between the middle suspension plate (12) and the lower suspension plate (13), and the two upper carbon fiber springs (14) and the two lower carbon fiber springs (14) are distributed in a cross shape.

5. The geomagnetic field vector observation device according to claim 1, characterized in that: The magnetic probe bracket mechanism comprises a spherical magnetic probe bracket (26), an inner spherical magnetic probe bracket (27), a bracket locking pressure block (28), a bracket rod (30) and a bracket seat (31); the bottom end of the bracket rod (30) is threadedly mounted on the bracket seat (31), and the top end passes through the non-magnetic turntable mechanism and the damping box (24) to extend into the spherical coil bracket (16) and is threadedly mounted on the inner spherical magnetic probe bracket (27); the spherical magnetic probe bracket (26) is angle-adjustably mounted in the inner spherical magnetic probe bracket (27) and is locked with the inner spherical magnetic probe bracket (27) by the bracket locking pressure block (28); a cylindrical hole is provided on the spherical magnetic probe bracket (26), and an optical pump magnetic sensor is mounted in the cylindrical hole.

6. The geomagnetic field vector observation device according to claim 1, characterized in that: The switching control circuit includes a switching circuit, a current source and a controller; the switching circuit includes a relay K1, a relay K2 and a relay K3; the D1 end of the current source is electrically connected to the S1 end of the spherical coil mechanism, and the S2 end of the spherical coil mechanism is electrically connected to the moving contact of the relay K1, one fixed contact of K2 and one fixed contact of K3 respectively; the fixed contact of the relay K1 is electrically connected to the D2 end of the current source, another fixed contact of the relay K2 and another fixed contact of the relay K3 respectively; one moving contact of the relay K2 is electrically connected to the B1 end of the Helmholtz coil (9) and one moving contact of the relay K3 respectively, and the other moving contact of the relay K2 is electrically connected to the B2 end of the Helmholtz coil (9) and another moving contact of the relay K3 respectively; the controller is used for controlling the on / off power of the coils of the relay K1, the relay K2 and the relay K3 respectively.

7. A method for adjusting the geomagnetic field vector observation device according to any one of claims 1 to 6, characterized in that: The steps include: Step 1, installing the non-magnetic turntable mechanism, placing the foot adjustment mechanism and the support seat (31) of the magnetic probe support mechanism on the observation pier and placing them in the middle of the observation pier; Step 2, adjusting the non-magnetic turntable mechanism so that the rotation axis of the Helmholtz coil (9) is in a vertical state; Step 3, given a compensation current, using a compass orientation, rotating the turntable (5) of the non-magnetic turntable mechanism to adjust the four counterweight rods (22) of the spherical coil mechanism to the four directions of east, west, south and north, first measuring the current orientation angle as the first horizontal component value, rotating the turntable (5) 180 degrees, and then measuring the current orientation angle as the second horizontal component value, then the difference between the first horizontal component value and the second horizontal component value is the horizontal component steering difference, adjusting the counterweight nuts (23) of the two spherical coil mechanisms in the north-south direction so that the horizontal component steering difference is less than 5nT, then rotating the turntable (5) 90 degrees, measuring the horizontal component steering difference in the current direction, and adjusting the two counterweight nuts (23) in the current north-south direction so that the horizontal component steering difference is less than 5nT; Step 4, rotate the turntable (5) to any angle, and determine whether the current horizontal component steering difference is less than 5nT. If it is less than 5nT, proceed to the next step; if it is greater than or equal to 5nT, return to step 3; Step 5: Orient the Helmholtz coil (9) with the compass, set the axial direction in the magnetic east-west direction, and fine-tune the orientation angle by the turntable (5), so that the measured synthetic magnetic field R + and R - Equal, at this time the axis of the Helmholtz coil (9) is the magnetic east-west direction, the horizontal component H1 and the horizontal component steering difference ΔH1 under the current direction are measured, and then the horizontal component value is calculated as H=H1-ΔH1 / 2, and then the vertical component is calculated based on the measured total magnetic field F Step 6: Rotate the turntable (5) of the non-magnetic turntable mechanism by 90 degrees, set the Helmholtz coil (9) axially in the magnetic north-south direction, measure the vertical component of the geomagnetic field, and set the compensation current of the vertical component of the geomagnetic field to H / K. h , K h is the coil constant of the Helmholtz coil (9), and the attitude adjustment screw (10) of the non-magnetic turntable mechanism is used to adjust the attitude of the Helmholtz coil (9) so that the measured vertical component is equal to the calculated vertical component, and then the turntable (5) is turned back to the initial angle of this step; Step 7, reselect a compensation current of the horizontal component, rotate the turntable (5) to any direction, and judge whether the current horizontal component steering difference should be less than 5nT. If it is less than, the adjustment of the observation device is completed, otherwise repeat steps 3-6.

8. A method for measuring magnetic declination based on the geomagnetic field vector observation device according to claim 6, characterized in that: The steps include: Step A, measure the initial direction N of the magnetic declination m :The controller of the switching control circuit controls relays K1, K2 and K3 to be disconnected, and the axis of the spherical coil of the spherical coil mechanism is adjusted to be vertically downward, and the axis of the Helmholtz coil (9) points to the magnetic east-west direction. The optical pump magnetic sensor measures the initial magnetic field total field F0. The initial magnetic field total field F0 can be decomposed into an initial horizontal component H0 on the horizontal plane and an initial vertical component Z0 perpendicular to the horizontal plane. At this time, the direction of the initial horizontal component H0 is the initial direction N of the magnetic declination angle. m ; Step B, measuring the horizontal component H and the vertical component Z: the controller of the switching control circuit controls relay K1 to close, relay K2 and relay K3 to open, and sets the current source current to I h The total magnetic field F is measured by the optically pumped magnetic sensor. The total magnetic field F can be decomposed into a horizontal component H on the horizontal plane and a vertical component Z perpendicular to the horizontal plane. At this time, the horizontal component H is related to the initial direction N of the magnetic declination. m The angle between them is θ; Step C, measure the biased synthetic magnetic field R + :The controller of the switching control circuit controls relay K2 to close, relay K1 and relay K3 are all disconnected, and the coil constant of the spherical coil is K s , the coil constant of the Helmholtz coil (9) is K h , the spherical coil and the Helmholtz coil (9) are simultaneously passed through the current I h At this time, a compensation magnetic field C1 is generated, and I h K s = Z1 = Z, and is opposite to the vertical component Z; then the composite magnetic field R of the compensating magnetic field C1 and the total magnetic field F + On the horizontal plane, the projection of the compensation magnetic field C1 on the horizontal component H is C 1h =I h K h , then: have to: Step D, measure the biased synthetic magnetic field R - :The controller of the switching control circuit controls the relay K3 to close, the relay K1 and the relay K2 are all disconnected, and the spherical coil and the Helmholtz coil (9) pass the current I at the same time. h , at this time, a compensation magnetic field C2 is generated, and I h K s = Z2 = Z, and is in the opposite direction to the vertical component Z; then the resultant magnetic field R of the compensating magnetic field C2 and the total magnetic field F is - On the horizontal plane, the projection of the compensation magnetic field C2 on the horizontal component H is C 2h =I h K h , then: have to: Step E: From equations (2) and (4), we can get: Then measure the initial direction N of the magnetic declination m The angle with the geographic north direction is D0, Then, the magnetic declination D=D0+θ.

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