High-Precision Protable Proton Magnetometer For Detecting Magnetic Fields

High-Precision Protable Proton Magnetometer For Detecting Magnetic Fields

Working principle
(I) Proton precession phenomenon
The proton magnetometer works based on the principle of proton precession (precession). The magnetic moment directions of protons in many liquids containing hydrogen atoms (such as kerosene, water, etc.) are randomly distributed when there is no external magnetic field. When in a stable external magnetic field (such as the earth's magnetic field), the proton magnetic moment will be arranged along the direction of the external magnetic field. If a radio frequency pulse magnetic field perpendicular to the direction of the earth's magnetic field is applied at this time, the proton magnetic moment will deviate from the direction of the external magnetic field. When the radio frequency pulse stops, the proton magnetic moment will precess around the direction of the earth's magnetic field.
(II) Measuring the precession frequency
The proton precession frequency is proportional to the strength of the external magnetic field, and the relationship conforms to the Larmor equation: , where is the precession frequency, is the proton gyromagnetic ratio (constant), and is the strength of the external magnetic field. By measuring the precession frequency of protons, the strength of the earth's magnetic field can be accurately calculated. In a proton magnetometer, an induction coil is usually used to detect the induced electromotive force generated by the precession of protons. Its frequency is the same as the proton precession frequency. After signal processing and analysis, the magnetic field value can be obtained.

Structural composition
(I) Probe part
The probe is a key component of the proton magnetometer. It contains a container for the proton source liquid and a radio frequency coil surrounding it. The probe needs to have good sealing and stability to ensure that the proton source liquid is not disturbed by the outside world and that the radio frequency coil can accurately generate and receive signals. In order to improve the measurement accuracy, the design of the probe often uses special materials and structures to reduce the interference of external electromagnetic fields.
(II) Host part
RF pulse generator: It is responsible for generating radio frequency pulses of precise frequency and intensity, which are transmitted to the radio frequency coil of the probe to stimulate the precession of protons. The radio frequency pulse generator of modern proton magnetometers has high-precision frequency control capabilities to ensure the accuracy of measurements.
Signal amplifier and filter: The proton precession signal received from the probe induction coil is usually very weak and needs to be amplified and filtered at multiple stages. The amplifier has high gain and low noise characteristics, which can effectively enhance the signal strength, while the filter can remove clutter and interference signals to make the measurement signal purer.
Frequency counter and data processing unit: The frequency counter is used to accurately measure the frequency of proton precession, and its measurement accuracy can reach an extremely high level. The data processing unit calculates the magnetic field strength based on the measured frequency and the Larmor equation, and performs operations such as storage, display and transmission of the data.
(III) Power supply system
The power supply system provides a stable power supply for the entire proton magnetometer. Since the instrument has high precision requirements, the stability of the power supply is crucial. Some proton magnetometers are equipped with rechargeable batteries and voltage stabilization circuits to ensure normal operation in different environments such as field operations, while reducing the impact of power supply fluctuations on measurement results.

Application

Magnetic mineral exploration: For iron, nickel, cobalt and other mineral resources with obvious magnetism, the proton magnetometer can directly detect the strong magnetic field anomaly generated by the ore body, so as to quickly determine the approximate location and range of the ore body, and improve the efficiency and accuracy of mineral exploration.
Indirect exploration of non-magnetic minerals: Some non-magnetic minerals, such as gold, silver, copper, etc., although they do not have obvious magnetism, may be accompanied by the paragenesis of magnetic minerals or changes in geological structure during their formation and occurrence, resulting in abnormal magnetic fields around them. Proton magnetometers can provide clues for finding non-magnetic minerals by detecting these indirect magnetic field anomalies.

Technical specifications: