CN103969603B - fluxgate magnetic gradiometer and coaxial adjusting method thereof - Google Patents

Abstract

The invention relates to a fluxgate magnetic force gradiometer and a coaxial adjustment method thereof, belonging to the field of weak magnetic field detection. A fluxgate magnetic gradiometer, in which adjustment screw holes are respectively provided on a pair of parallel side walls of the box body of the installation box at both ends of the probe rod of the gradiometer, and the two installation boxes are provided with adjustment screw holes The side walls are perpendicular to each other, and the sensitive axes of the two uniaxial fluxgate sensors are coaxially fixed in the installation box along the axial direction of the probe rod; a coaxial adjustment method of the fluxgate magnetic force gradiometer, the magnetic flux The door magnetic gradiometer is vertically fixed on the non-magnetic calibration table, and the set screws used to fix the fluxgate at both ends are repeatedly and alternately fine-tuned until the difference between the magnetic flux readings of the two fluxgates is less than 1nT, and finally the two fluxgates are It is permanently fixed in the installation box with silicone to complete the coaxial adjustment. In the fluxgate magnetic gradiometer described in the present invention, the adjustment in two directions will not interfere with each other, which effectively simplifies the coaxial adjustment process and improves the accuracy of the coaxial adjustment.

Description

Fluxgate Magnetic Gradient and Its Coaxial Adjustment Method

technical field

The invention relates to a fluxgate magnetic gradiometer, in particular to a coaxial adjustment method for a fluxgate magnetic gradiometer.

Background technique

Fluxgate magnetometers are mainly used for the measurement of weak low-frequency static magnetic fields, such as the earth's magnetic field, biological magnetic field, and the detection of underground ferromagnetic embedded parts. However, when the measured magnetic field is very weak and the ambient noise is large, the effective signal is often submerged by the ambient noise, resulting in a greatly reduced detection effect. The fluxgate magnetic gradiometer can better overcome the above limitations, and its advantage is that it can greatly eliminate the influence of external interference signals, and it can work as usual even when strong magnetic disturbances and magnetic storms occur. Fluxgate magnetic gradiometers are usually used in the fields of metal mineral resource exploration, underground pipeline detection, underground cultural relics archaeological positioning, and various weak magnetic field change monitoring and other fields. Due to the vector measurement characteristics of the fluxgate, it can monitor the change of the magnetic field component in a certain direction, especially the gradient measurement of the vertical component has a very prominent effect on the boundary determination of the detection object. At present, the common fluxgate magnetic gradiometer is to install two single-component fluxgates at both ends of a fixed probe rod, and measure the magnetic field strength at two points respectively, thereby obtaining the gradient value of the axial magnetic field of the probe rod. However, since the fluxgate sensor is a vector measuring sensor, it is very sensitive to the direction of the measured magnetic field, if the direction of the two single-component fluxgates of the above-mentioned fluxgate magnetic gradiometer deviates, the measurement results will be seriously distorted .

Taking China as an example, the vertical component value of the earth's magnetic field is about 30000nT. Assuming that the deviation angle of the two fluxgate sensors in the fluxgate magnetic gradiometer is 1°, the resulting measurement error is: 30000× (1-cos1°)=4.6(nT); In fact, the installation angle error of a general fluxgate often reaches 2° to 3° or even greater, and the resulting measurement error is very large, so when making a fluxgate When using a magnetic gradiometer, it is necessary to make precise coaxial adjustments to the directions of the two sensors so that the installation angle error of the two sensors is as small as possible, for example:

When the error angle is 0.5°, 30000×(1-cos0.5°)=1.1(nT);

When the error angle is 0.2°, 30000×(1-cos0.2°)=0.18(nT).

At present, when making a fluxgate magnetic gradiometer, usually the fluxgate sensor at one end is fixed first, and the fluxgate sensor at the other end adopts a movable connection. By adjusting the fluxgate sensor that is movable connected, the two fluxgate sensors reach coaxial. As shown in Figure 1, the fluxgate magnetic gradiometer consists of a probe rod, an installation box fixed at both ends of the probe rod, and a single-axis fluxgate sensor placed in the installation box. The installation box includes a box and a cover, one of which is A single-axis fluxgate sensor is fixedly installed in the installation box, and the bottom of the box of the other installation box and a pair of side walls adjacent to the probe rod are respectively provided with adjustment screw holes. Fixed in the installation box. When coaxially adjusting the fluxgate magnetic gradiometer, energize the two single-axis fluxgate sensors at the same time, observe their readings, and fine-tune the set screws on both sides of the box to make the single-axis fluxgate sensors in the horizontal direction For adjustment, fine-tune the set screw at the bottom of the box to adjust the single-axis fluxgate sensor in the vertical direction. After repeated and alternate fine-tuning, the coaxial adjustment of the fluxgate magnetic gradiometer is finally realized, but because only one of the single-axis The adjustment of the fluxgate sensor in the horizontal and vertical directions will cause mutual interference, and only one side of the vertical direction has an adjustment screw hole, which makes the adjustment process complicated and uncertain, and eventually leads to a large error in the fluxgate magnetic gradiometer .

Contents of the invention

The technical problem to be solved by the present invention is to provide a fluxgate magnetic gradiometer, which can simplify the coaxial adjustment process and improve the accuracy of the fluxgate magnetic gradiometer.

The present invention is achieved through the following technical solutions:

A fluxgate magnetic gradiometer, comprising a probe rod, an installation box and a single-axis fluxgate sensor, the installation box includes a box body and a cover, the probe rod and the installation box are made of non-magnetic aluminum, the A pair of parallel side walls of the box body are provided with symmetrical adjustment screw holes, and the uniaxial fluxgate sensor is fixed in the installation box by set screws, and the installation boxes are respectively fixed at both ends of the probe rod, and installed A pair of parallel side walls with adjustment screw holes in the box are respectively perpendicular to the end of the probe rod, and the two pairs of parallel side walls with adjustment screw holes on the two installation boxes at both ends of the probe rod are perpendicular to each other, and The sensitive axis of the single-axis fluxgate sensor in the installation box is arranged coaxially along the axial direction of the probe rod.

A method for coaxial adjustment of the aforementioned fluxgate magnetic gradiometer, comprising the steps of:

Step 1. Select an area where the geomagnetic field is relatively stable as the measurement site for the non-magnetic calibration table, fix the fluxgate magnetic gradiometer vertically on the non-magnetic calibration table, and connect two single-axis fluxgate sensors to the computer. Observe the magnetic flux readings measured by the two single-axis fluxgate sensors from the computer;

Step 2. Repeatedly and alternately adjust the set screws on the installation boxes at both ends of the fluxgate magnetic gradiometer, so that the single-axis fluxgate sensors in the two installation boxes move in two mutually perpendicular directions, and adjust to two The difference between the magnetic flux readings of the single-axis fluxgate sensor is less than 1nT;

Step 3. Use quick-drying glue to fix the two single-axis fluxgate sensors in the installation boxes at both ends of the fluxgate magnetic force gradiometer, and then use insulating silicone to permanently fix the two single-axis fluxgate sensors to complete the fluxgate. Coaxial adjustment of the gate magnetic gradiometer.

The intentional effect of the present invention is that the two installation boxes are respectively provided with adjustment screw holes, the two uniaxial fluxgate sensors are adjusted in two mutually perpendicular single directions, and the adjustments in the two directions will not interfere with each other , which effectively simplifies the coaxial adjustment process and improves the accuracy of the coaxial adjustment.

Description of drawings

Fig. 1 is the structural representation of existing fluxgate magnetic force gradiometer;

Fig. 2 is the structural representation of fluxgate magnetic gradiometer of the present invention;

Fig. 3 is the partially enlarged schematic view of the fluxgate magnetic gradiometer of the present invention;

Fig. 4 is a schematic diagram of the coaxial adjustment method of the fluxgate magnetic gradiometer of the present invention.

Among them: 1-JJG-2 non-magnetic calibration table, 11-fixture, 2-computer, 3-fluxgate magnetic gradient meter, 31-uniaxial fluxgate sensor, 32-probing rod.

detailed description

The present invention will be further described below in conjunction with specific embodiments and accompanying drawings.

As shown in Figure 2 and Figure 3, it is a schematic structural diagram of a fluxgate magnetic gradiometer, including a probe rod, two installation boxes and two single-axis fluxgate sensors, the installation box includes a box body and a cover, and the Both the probe rod and the installation box are made of non-magnetic aluminum, symmetrical adjustment screw holes are provided on a pair of parallel side walls of the box body, and the single-axis fluxgate sensor is fixed in the installation box by set screws , the installation boxes are respectively fixed on the two ends of the probe rod, the installation box is provided with a pair of parallel side walls of the adjustment screw holes which are respectively perpendicular to the ends of the probe rod, and the two installation boxes at the two ends of the probe rod are provided with adjustment The two pairs of parallel side walls of the screw holes are perpendicular to each other, and the sensitive axes of the single-axis fluxgate sensors in the two installation boxes are arranged coaxially along the axial direction of the probe rod. When the fluxgate magnetic gradiometer with this structure is coaxially adjusted, the uniaxial fluxgate sensors at both ends of the gradiometer only move in a single direction without mutual interference, which can effectively simplify the coaxial adjustment process.

As shown in FIG. 4 , it is a schematic diagram of the connection of the fluxgate magnetic gradiometer 3 when performing coaxial adjustment.

When the fluxgate magnetic force gradiometer 3 was adjusted coaxially, the following equipment was used: JJG-2 non-magnetic correction table 1, computer 2 and fluxgate magnetic force gradiometer 3 based on single-axis fluxgate sensor technology, described The fluxgate magnetic gradiometer 3 includes a probe rod 32, two square installation boxes and two uniaxial fluxgate sensors 31, wherein the probe rod 32 and the installation box are both made of non-magnetic aluminum, and the installation box is made of the box body and cover composition.

A coaxial adjustment method of a fluxgate magnetic gradiometer 3 specifically includes the following steps:

Step 1. Select an area where the geomagnetic field is relatively stable as the measurement site for placing the JJG-2 non-magnetic calibration table 1, and fix the probe rod 32 of the fluxgate magnetic gradiometer 3 vertically through the jig 11 of the JJG-2 non-magnetic calibration table 1 On the JJG-2 non-magnetic correction table 1, connect two uniaxial fluxgate sensors 31 to the computer 2, and observe the magnetic flux readings measured by the two uniaxial fluxgate sensors 31 from the computer 2;

Step 2. First adjust the set screw of the uniaxial fluxgate sensor 31 at one end so that the magnetic flux readings of the two uniaxial fluxgate sensors 31 tend to be equal, and then adjust the uniaxial fluxgate sensor 31 at the other end. Tighten the screw so that the difference between the magnetic flux readings of the two uniaxial fluxgate sensors 31 is further reduced, so that the difference between the magnetic flux readings of the two uniaxial fluxgate sensors 31 is adjusted alternately to less than 1nT;

Step 6. First fix the two single-axis fluxgate sensors 31 in the installation boxes at both ends of the fluxgate magnetic force gradiometer 3 with quick-drying glue, and then use insulating silica gel to permanently fix the two single-axis fluxgate sensors 31 , and cover the cover of the installation box to complete the coaxial adjustment of the fluxgate magnetic gradiometer 3 .

Claims (1)

1. A coaxial adjustment method of a fluxgate magnetic gradiometer, the fluxgate magnetic gradiometer includes a probe rod, an installation box and a single-axis fluxgate sensor, and the installation box includes a box body and a cover, and the Both the probe rod and the installation box are made of non-magnetic aluminum, symmetrical adjustment screw holes are provided on a pair of parallel side walls of the box body, and the single-axis fluxgate sensor is fixed on the installation box by set screws. Inside, the installation boxes are respectively fixed on the two ends of the probe rod, the installation box is provided with a pair of parallel side walls of the adjustment screw holes which are respectively perpendicular to the ends of the probe rod, and the two installation boxes at the two ends of the probe rod are provided with The two pairs of parallel side walls of the adjustment screw holes are perpendicular to each other, and the sensitive axes of the uniaxial fluxgate sensors in the two installation boxes are arranged coaxially along the axial direction of the probe rod; it is characterized in that the method includes the following step: Step 1. Select an area where the geomagnetic field is relatively stable as the measurement site for the non-magnetic calibration table, fix the fluxgate magnetic gradiometer vertically on the non-magnetic calibration table, and connect two single-axis fluxgate sensors to the computer. Observe the magnetic flux readings measured by the two single-axis fluxgate sensors from the computer; Step 2. Repeatedly and alternately adjust the set screws on the installation boxes at both ends of the fluxgate magnetic gradiometer, so that the single-axis fluxgate sensors in the two installation boxes move in two mutually perpendicular directions, and adjust to two The difference between the magnetic flux readings of the single-axis fluxgate sensor is less than 1nT; Step 3. Use quick-drying glue to fix the two single-axis fluxgate sensors in the installation boxes at both ends of the fluxgate magnetic force gradiometer, and then use insulating silicone to permanently fix the two single-axis fluxgate sensors to complete the fluxgate. Coaxial adjustment of the gate magnetic gradiometer.