Overhauser磁力仪传感器研究与设计

发布时间：2018-03-31 08:16

本文选题：质子磁力仪　切入点：Overhauser磁力仪　出处：《吉林大学》2017年硕士论文

【摘要】：质子磁力仪传感器主要利用直流脉冲信号对氢质子进行极化,使其产生与地磁场垂直的极化磁场,氢质子沿地磁场与极化磁场的矢量和方向产生宏观合磁矩,撤去脉冲信号氢质子产生拉莫尔旋进现象,这种传感器存在高能耗、低精度等缺点。在质子磁力仪传感器的基础上,对Overhauser磁力仪传感器进行研制:引入射频激励信号使氮氧自由基溶液产生电子与核双共振现象(Overhauser效应),增强氢质子沿地磁场方向的磁化强度,解决质子磁力仪传感中氢质子旋进信号过弱的问题,从而提高传感器的测磁精度。本课题组已自主研制出JOM-1型和JOM-2型Overhauser磁力仪样机,二者相比较而言,它们的灵敏度分别达到0.14n T和0.08n T,说明JOM-2型磁力仪灵敏度得到较大改善,但仍存在提升空间。本文主要从射频功放电路的改进和传感器的研究与设计两个方面对JOM-2型磁力仪进行改进介绍:第一,将JOM-1型磁力仪中的DDS系统芯片更换为AD9859,实现低功耗和精准频率输出的指标;第二,将JOM-2型磁力仪中单路射频功率放大电路改进为双路射频功放电路,构成梯度仪,实现同时对两个传感器进行射频极化,降低了双路测试时传感器信号的相互影响;第三,对传感器的极化采集部分和高频激发部分进行仿真和分析,对比JOM-1型和JOM-2型磁力仪高频激发部分的优缺点,选取合适的结构组成新型传感器,并验证不同的制作材质、屏蔽材质、溶液、极化时间和功率大小等因素对传感器品质因数(Q值)、回波损耗(S11)和信号采集的影响。传感器的实验研究表明:传感器的Q值愈高,S11越小,传感器的功耗越小,对外界磁场变化愈敏感;不同浓度配比的氮氧自由基溶液具有不同的激发频率和信号采集效果。最终,成功集成了新型传感器并进行野外实测,实测结果表明:改进后的JOM-2型磁力仪各项性能稳定,磁场测试结果准确可靠,并将灵敏度提高为0.057nT。
[Abstract]:The sensor of proton magnetometer mainly uses DC pulse signal to polarize hydrogen proton to produce polarized magnetic field perpendicular to geomagnetic field. Hydrogen proton produces macroscopic magnetic moment along the vector and direction of geomagnetic field and polarization magnetic field. Removing the pulse signal from the hydrogen proton produces Lamole precession, which has the disadvantages of high energy consumption and low precision. Based on the proton magnetometer sensor, The Overhauser magnetometer sensor has been developed: introducing RF excitation signal to make nitrogen-oxygen radical solution produce electron and nuclear double resonance phenomenon overhauser effect and enhance the magnetic intensity of hydrogen proton along the direction of geomagnetic field. The problem of weak hydrogen proton precession signal in proton magnetometer sensor is solved and the magnetic precision of the sensor is improved. The prototype of JOM-1 type and JOM-2 type Overhauser magnetometer has been developed by our team. Their sensitivities reached 0.14nT and 0.08nT respectively, which indicated that the sensitivity of JOM-2 magnetometer was improved greatly. But there is still room for lifting. This paper mainly introduces the improvement of JOM-2 magnetometer from the aspects of RF power amplifier circuit improvement and sensor research and design: first, The DDS system chip in the JOM-1 magnetometer is replaced with AD9859 to realize the index of low power consumption and accurate frequency output. Secondly, the single-channel RF power amplifier circuit in the JOM-2 type magnetometer is improved to a two-channel RF power amplifier circuit to form a gradiometer. At the same time, the two sensors are polarized at the same time, which reduces the mutual influence of sensor signals. Thirdly, the polarization acquisition part and the high-frequency excitation part of the sensor are simulated and analyzed. Comparing the advantages and disadvantages of the high frequency excitation parts of JOM-1 and JOM-2 magnetometers, choosing the appropriate structure to form a new type sensor, and verifying the different fabrication materials, shielding materials, solutions, The effects of polarization time and power on the sensor quality factor (Q value), echo loss (S 11) and signal acquisition. The experimental study of the sensor shows that the higher the Q value of the sensor is, the smaller the S11 is, and the smaller the power consumption of the sensor is. The more sensitive to the change of external magnetic field, the more sensitive the nitrogen-oxygen free radical solution with different concentration has different excitation frequency and signal acquisition effect. Finally, the new sensor has been successfully integrated and tested in the field. The measured results show that the improved JOM-2 magnetometer has stable properties, accurate and reliable magnetic field test results, and the sensitivity is increased to 0.057nT.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TP212

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