The proton precession magnetometer uses a proton-rich hydrogen-rich liquid to generate a precession signal. The liquid it uses provides very high hydrogen density and is not hazardous during operation. Passing a polarized DC current through a coil wound around a proton-rich hydrogen liquid probe
Auxiliary flux density of 100 Gauss. The protons are polarized to a stronger net magnetization and reach a thermal equilibrium with a stronger magnetic flux density. When the auxiliary flux terminates, the "polarized" protons spin and return to the normal flux density state. According to the following formula, the proton's precession frequency f 0 is directly related to the magnetic flux density B (in Tesla-Teslas, T):
f 0 = (γ
p
/2π)Bγ p /2π=42.5763751MHz/TThe measurement of proton precession must be performed in order, that is, there is an initial polarization followed by a frequency measurement, and then the cycle is repeated. This is different from continuous measurement in which the precession measurement is performed while the hydrogen nuclei are polarized.
In layman's terms: I compare the magnetic domain of a large number of hydrogen atoms in the probe to countless small magnetic needles. From the force, the small magnetic needle is not subject to any force in the vacuum environment, so the arrangement of small magnetic needles should be Casual, disorganized, in any direction. If a small magnetic needle is placed inside the probe and an additional magnetic field is applied (polarization process), then the small magnetic needle should be subjected to two forces, one is the force of the applied magnetic field, and the other is the force of the earth's magnetic field (the compass is It has the function of helping people to indicate the direction due to the influence of the earth's magnetic field. Due to the influence of the force of the applied magnetic field, the small magnetic needles are sequentially arranged in one direction according to the direction of the applied magnetic field. If the external magnetic field is cancelled later, then the small magnetic needle is only subjected to the force of the magnetic field at the position of the measuring point. Due to the influence of the geomagnetic field force, the small magnetic needle will change from the fixed sequential direction of the appeal to the corresponding direction of the geomagnetic field under the current force requirement. At the same time, the proton rotates (spin) around its own nucleus. The form of motion exhibited by the proton under the action of the earth's magnetic field is like a tilting rotating gyro. We call it the "Larmor precession." Theoretical physics analysis shows that the angular velocity of angular proton rotation (angular velocity)
=2Ï€f, the f is the proton precession frequency) is related to the magnitude of the geomagnetic field at the measuring point. The stronger the geomagnetic field at the measuring point, the faster the precession, and the slower. Through the reasonable combination of electronic equipment, f can be measured to obtain the magnetic field strength value of the geomagnetic field at the measuring point.
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