OVH magnetic sensor cavity based on capacitance loading coaxial resonant cavity

Abstract

The invention discloses an OVH magnetic sensor cavity based on a capacitor loading coaxial resonant cavity. The OVH magnetic sensor cavity comprises a cavity conductor, a loading capacitor, an adjustable capacitor and a connecting capacitor, wherein the cavity conductor is a concentric cylinder and comprises an inner conductor and an outer conductor; the inner conductor is a hollow cylinder with a closed top end and an unclosed bottom end, the outer conductor is provided with a plurality of open holes from a lower end to a top end, the outer conductor is divided into a plurality of strips, the top end is equally divided into four groups, and every two adjacent groups are connected through a connecting capacitor; the inner conductor and the outer conductor are directly connected at a bottom end to form short circuit; top ends of the inner conductor and the outer conductor are connected through a loading capacitor to form an open circuit; the adjustable capacitor is arranged in the center of the top end of the inner conductor. According to the sensor cavity, the resonant frequency of the cavity can be changed by adjusting the loading capacitor and the adjustable capacitor, so effective excitation of free radical solutions at different excitation frequency points is realized; the eddy current generated by the radio frequency magnetic field in the cavity conductor is inhibited under the strip-shaped structure of the outer conductor, so energy loss is reduced, and excitation efficiency is improved.

Description

technical field [0001] The invention relates to the technical field of geomagnetic field measurement sensors, in particular to an OVH magnetic sensor cavity based on a capacitively loaded coaxial resonant cavity. Background technique [0002] The Overhauser (OVH) magnetic sensor is a weak magnetic measurement sensor based on the Dynamic Nuclear Polarization (DNP) effect of free radicals. It has the characteristics of high precision and high sensitivity. Measurement, military and various engineering fields have been widely used. The dynamic nuclear polarization of free radicals in the OVH magnetic sensor is the key to the sensor's work. Only by effectively exciting the free radical solution and generating high-quality FID signals can the value of the geomagnetic field be accurately measured. According to the electron paramagnetic resonance theory, the frequencies required for the dynamic nuclear polarization of different free radical solutions are not exactly the same. In or...

AI Technical Summary

Problems solved by technology

However, the OVH magnetic sensor needs high-frequency excitation, and the LC resonant circuit has great disadvantages when the frequency is high: the size of the LC element is too small at high-frequency resonance, which is not conducive to production; the energy storage of the circuit is reduced, and the quality factor is significantly reduced. Large loss

The structure of the cage coil is simple and easy to realize, but the power loss in the coil is large, resulting in low polarization efficiency of free radicals, and the radius of the end ring of the cage coil, the length of the rung, the number of rungs and the matching capacitance are all aligned with the frequency point Once the structure is determined, the frequency point adjustment will become less easy, and the operation difficulty will be greatly increased when dealing with free radicals with different excitation frequencies

[0003] Therefore, the traditional OVH magnetic sensor has the following technical problems: (1) the size of the LC element is too small when the LC resonant circuit resonates at a high frequency, which is not conducive to production, the energy storage of the circuit is reduced, the quality factor is significantly reduced, and the circuit loss is large; (2) ) The typical resonant cavity is too large and inconvenient to manufacture and carry; (3) The quality factor of the cage coil is low, the power loss is large, and the polarization efficiency is low, and the design difficulty increases when facing free radicals with different excitation frequencies

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