Novel radio frequency excitation system based on overhauser effect

Abstract

The invention provides a novel radio frequency excitation system based on an overhauser effect, which belongs to the technical field of magnetic field measurement sensors. The system comprises a radiofrequency signal source module, a radio frequency power amplification module and a radio frequency excitation module. The radio frequency excitation module adopts an Alderman-Grant coil to replace atraditional structure, the quality factor of the coil is higher, the sensitivity of an output signal is improved, and the polarization degree of a working substance in the overhauser magnetometer is high. Under the condition that the size of the coil is fixed, the resonant frequency required by the coil can be obtained only by adjusting the tuning capacitance value in the simulation process, so that the coil can adapt to different working substances. The coil equivalent circuit is simple in structure, and the coil can be tuned in a required frequency range more easily.

Description

technical field [0001] The invention belongs to the technical field of magnetic field measurement sensors, in particular to a novel radio frequency excitation system based on the overhauser effect. Background technique [0002] The proton magnetometer is an important scientific instrument for measuring the geomagnetic field. The ordinary proton magnetometer mainly adopts the static polarization method. By passing direct current to the coil, the excitation current is cut off after a period of time. At this time, a magnetic field is induced on the coil. A Larmor precession signal, the precession frequency of the signal has a certain proportional relationship with the strength of the earth's magnetic field, and the total strength of the earth's magnetic field can be calculated by measuring the precession frequency of protons. However, in the static polarization mode, the degree of proton excitation is low, so that the amplitude of the output signal is extremely weak, and the se...

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Problems solved by technology

For the capacitance-loaded coaxial resonant cavity, since its resonant frequency is related to various parameters such as the size of the resonant cavity and the tuning capacitance value, it is necessary to change the parameters such as the size of the resonant cavity and the tuning capacitance value at the same time to carry out various simulation experiments. Huge amount, more difficult

For the cage coil, its quality factor is too low, and the power loss is very large. Most of the power sent by the RF excitation is consumed by the cage coil instead of being stored inside the cage coil. This phenomenon has a great impact on the free radical solution. RF polarization is very unfavorable, it will affect the acquisition quality of Larmor precession signal and affect the sensitivity of magnetometer

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