Research And Design Of The Proton Precession Magnetometer Sensor

In the environment of Human life,it is filled with an invisible,intangible special form substance-magnetic field at all times.As one of nature’s basic field,the impact is very significant.Static geomagnetic field and dynamic electromagnetic field always exist in any corner of the world.With the development of science and technology and in-depth human cognition of nature,measurements of magnetic field has become an important means of human exploration of the nature,for the magnetic field measurement accuracy requirements are also increasing.Proton precession magnetometer is one of the magnetic field measuring instruments,which can accurately measure weak geomagnetic field signals.It is developed in use of proton Larmor precession phenomenon in the magnetic field,and now is being widely used in various fields such as energy,exploration,medicine,biology,military,scientific research and so on with the feature of stable signal,high accuracy,good reliability,affordable prices,simple operation and easy to carry.Currently,its basic development trends include high-precision,intelligent,low-power,portable etc,not only the hardware systems are maturing,the software algorithms are also developing rapidly,and the improvement of technical indicators and the enhancement of peripheral functions make it used in various environments.However inadequately,existing studies have focused on the basic electronic circuit design,data processing algorithms and use function Improvement,the research for the important part of the instrumentation system-sensor part is progressing relatively slowly,there is Less relevant literature and no relatively complete analysis and design methods,sensor’s structure form is single,directional detection and other issues have not been a good solution.The quality of sensor receiving signals directly affect the outcome of detecting,so the study of the sensor has a very important significance.Based on the "Twelfth Five-Year" national significant scientific instrument equipments developed special project "Water Disasters(Mine/Tunnel)Direct Detection Instruments and Equipment Development and Application"(2011 YQ030133),the main contents are as follows:First,in the introduction,we outline the development,application areas and other basic information of the magnetometer,and discuss the proton precession magnetometer’s basic principles,applications,development history,current domestic and foreign status and future trends as well as the significance of this paper.Second,we analyze Larmor precession phenomena,principle of Nuclear Magnetic Resonance and proton precession magnetometer works in detail.We also discuss how the synthetic magnetic moment of the proton system to form and change under the external magnetic field in classical mechanics and quantum physics point of view,then give the basic block diagram of the instrumentation system.Third,we study the traditional against-interference coil model of the sensor,get the initial signal amplitude calculation formula via mathematical derivation,combined with the synthetic magnetic moment of the proton system precession model.Also,we analyze the noise of instrumentation system and establish system own noise equivalent calculation model.Forth,according to the basic against-interference coil model,combined with limiting conditions in actual design,we analyze to get the limiting parameters and design parameters of the sensor coil design,then derive the function relationship between them,research limiting parameters’ change in the influence of the design parameters by parameters graphics processing in Matlab,finally,we get the general steps of sensor coil design and give the actual design examples.Fifth,we discuss sensor Internal solution and directional detection question,in case of water,ethanol,kerosene,analyze different parameters of sample solution affect to measurement.By analyzing reason of sensor directional detection,combined with characteristics of the sensor receiving signal,we get the basic structure of omni-directional detection sensor.Sixth,by repeated measurements of the geomagnetic field experiments,omni-directional sensor signal measurements experiments,magnetic anomaly detection experiments,we test sensors designed,they work well and the methods of analysis and design are stable and feasible.