Design Of JOM-2 Overhauser Magnetometer

Overhauser magnetometer is a static magnetic measuring instrument based on the Overhauser effect. It has characteristics of small size, low power consumption and high sensitivity, is widely used in archaeological exploration, mineral resources exploration, oil and gas basin structure detection, prediction of engineering exploration environment, earthquakes and volcanic eruptions, object magnetic measurements and underground burial objects exploration. With high frequency excitation, it produces the non-paired valence electrons paramagnetic resonance in the free radical solution. The electrons are driven by the nucleus to produce nuclear magnetic resonance. With external magnetic field provided by direct current polarization, magnetization direction is close to magnetic field. Then quickly shut off the external magnetic field, the nuclei of the atoms will revolve around the geomagnetic field direction, which is called the Larmor precession. The magnetic field value can be calculated by measuring the Larmor signal of the coil.In this paper, we first introduce the development and research significance of Overhauser magnetometer. Then we expound the working principle and the structure design. The hardware circuit structure and the software framework of JOM-2 Overhauser magnetometer system is designed by reading related articles and debugging circuit. The influence of some parameters and methods of magnetometer sensitivity is discussed in this paper. At the same time, the influence of sensor noise, signal to noise ratio and polarization circuit of the instrument signal is studied.We successfully debugged all functional modules and produced a JOM-2 prototype. The measurement results show that the JOM-2 Overhauser magnetometer can realize the basic functions of automatic matching, signal acquisition, measurement frequency, data storage, data transmission, and waveform display and so on. The experiment results show that JOM-2 Overhauser magnetometer functions are stable and can acquire accurate and reliable measurement data of magnetic field. Contrast test of JOM-2 magnetometer and GSM-19 magnetometer indicated that the sensitivity of JOM-2 magnetometer is 0.085nT. At last, the JOM-2 Overhauser gradient magnetometer is designed. The test results show that the sensitivity of JOM-2 Overhauser gradient magnetometer is 0.059nT.