Overhauser磁力仪探头激发频率测试仪研制
发布时间：2019-03-25 08:57
【摘要】：Overhauser磁力仪探头中自由基溶液激发频率的精度直接决定探头输出拉莫尔旋进信号的质量.为准确获得激发频率,本文设计了一种Overhauser磁力仪探头激发频率测试仪.针对目前测试设备存在的分辨率较低、操作复杂等问题,采用高分辨率DDS作为可控射频信号源;运用ADC同步采集技术,结合归一化数据处理方法有效解决50MHz~100MHz范围内幅频特性曲线不平坦的问题;采用射频功放、小信号放大作为辅助测量通道,实现仪器的标准、辅助测量一体化.通过对探头谐振腔的等效电路进行仿真,得到微调电容对探头谐振频率和品质因数的影响程度,并用商用探头进行测试,进一步验证仿真结果;同时得到自由基溶液的极化度与射频激发功率、激发时间的关系.最终实验结果表明,利用本文研制的Overhauser磁力仪探头激发频率测试仪,能够准确测量自由基溶液的激发频率、频率带宽以及品质因数,还可用于在磁力仪设计过程中对激发功率和激发时间的确定,为进一步设计Overhauser磁力仪奠定了基础.
[Abstract]:The precision of excitation frequency of free radical solution in the probe of Overhauser magnetometer directly determines the quality of Lamor precession signal output by probe. In order to obtain the excitation frequency accurately, a kind of Overhauser magnetometer probe excitation frequency tester is designed in this paper. In order to solve the problems of low resolution and complex operation of test equipment, high resolution DDS is used as the controlled RF signal source. The problem of amplitude-frequency characteristic curve unevenness in the range of 50MHz~100MHz is solved effectively by using ADC synchronous acquisition technology and normalized data processing method. RF power amplifier and small signal amplification are used as auxiliary measurement channels to realize the standard of instrument and the integration of auxiliary measurement. Through the simulation of the equivalent circuit of the probe resonator, the influence degree of the fine-tuning capacitance on the resonant frequency and quality factor of the probe is obtained, and the commercial probe is tested to further verify the simulation results. At the same time, the relationship between polarization degree of free radical solution and RF excitation power and excitation time is obtained. The final experimental results show that the Overhauser magnetometer probe excitation frequency tester developed in this paper can accurately measure the excitation frequency, frequency bandwidth and quality factor of free radical solution. It can also be used to determine the excitation power and time during the design of the magnetometer, which lays a foundation for the further design of the Overhauser magnetometer.
【作者单位】： 中国地质大学地球物理与空间信息学院;中国地质大学自动化学院;近地面探测技术重点实验室;
【基金】：国家自然科学基金(No.41474158,No.41504137) 国家重大科学仪器设备开发专项(No.2014YQ100817) 近地面探测技术重点实验室开放课题(No.TCGZ2015A008) 武汉市科技局应用基础研究计划项目(No.2016010101010013)
【分类号】：TM935.1
本文编号：2446827
[Abstract]:The precision of excitation frequency of free radical solution in the probe of Overhauser magnetometer directly determines the quality of Lamor precession signal output by probe. In order to obtain the excitation frequency accurately, a kind of Overhauser magnetometer probe excitation frequency tester is designed in this paper. In order to solve the problems of low resolution and complex operation of test equipment, high resolution DDS is used as the controlled RF signal source. The problem of amplitude-frequency characteristic curve unevenness in the range of 50MHz~100MHz is solved effectively by using ADC synchronous acquisition technology and normalized data processing method. RF power amplifier and small signal amplification are used as auxiliary measurement channels to realize the standard of instrument and the integration of auxiliary measurement. Through the simulation of the equivalent circuit of the probe resonator, the influence degree of the fine-tuning capacitance on the resonant frequency and quality factor of the probe is obtained, and the commercial probe is tested to further verify the simulation results. At the same time, the relationship between polarization degree of free radical solution and RF excitation power and excitation time is obtained. The final experimental results show that the Overhauser magnetometer probe excitation frequency tester developed in this paper can accurately measure the excitation frequency, frequency bandwidth and quality factor of free radical solution. It can also be used to determine the excitation power and time during the design of the magnetometer, which lays a foundation for the further design of the Overhauser magnetometer.
【作者单位】： 中国地质大学地球物理与空间信息学院;中国地质大学自动化学院;近地面探测技术重点实验室;
【基金】：国家自然科学基金(No.41474158,No.41504137) 国家重大科学仪器设备开发专项(No.2014YQ100817) 近地面探测技术重点实验室开放课题(No.TCGZ2015A008) 武汉市科技局应用基础研究计划项目(No.2016010101010013)
【分类号】：TM935.1
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