磁场均匀性对光学磁力仪共振线宽的影响

发布时间：2019-06-12 19:59

【摘要】：微弱磁场的精确测量,作为研究磁体、分析物质形态及性质的一种重要手段,在实际应用中,例如医学中生物体磁场的测量、地质勘查中地形地貌的研究、工艺加工中材料缺陷的检测以及矿产油气勘察、水下磁性目标定位和考古学等领域中起着重要作用。目前已广泛应用的、技术比较成熟的磁力仪种类包括磁通门磁力仪、核子旋进磁力仪,光泵磁力仪和超导磁力仪等,这些磁力仪的灵敏度都比较高。在磁力仪测磁灵敏度方面,我们主要依靠原子磁共振光谱谱线的线宽与磁场的关系进行测量。而磁场本身会受到空间、温度、湿度等因素的影响,即使在稳态环境中,也还是会随时间的变化而发生改变,所以我们考虑采用磁场的均匀程度代替磁场进行测量。本文首先讲述了磁力仪在多个领域的重要应用;阐述了磁共振光谱的线宽与磁场的关系对原子磁力仪的重要影响;给出了原子磁力仪相关光谱线型及线宽的主要特征及其影响因素;随后针对本课题组要求的磁场的均匀性,对不同形状的载流线圈产生的磁场进行仿真计算;按照仿真设计的尺寸制作实物矩形线圈组并进行测量;最后针对弱磁场和强磁场下的磁共振光谱与磁场均匀性分析研究。以下是本文的主要研究内容:1、详细介绍了磁测技术的应用及意义,给出几种磁力仪的设计方案,并针对磁场均匀性对磁力仪及其灵敏度的意义进行分析,引出本文的主要内容。2、说明了选择Cs原子作为工作物质的优势所在,针对本文中涉及的磁共振线宽的基本理论进行详细介绍,给出几种线宽对磁力仪的影响,并在此基础上讨论了传统载流圆形线圈—亥姆霍兹线圈产生磁场的特性及铯原子磁力仪的系统。3、系统地分析研究了常用的圆形线圈及优化的矩形线圈产生的磁场,及相应的在实验部分中的均匀性。通过仿真计算载流圆形、矩形线圈中心部分的磁场,对它们进行对比分析,并得出了矩形线圈更适用于高灵敏度的原子磁力仪的结论。4、根据磁屏蔽装置,设计适合的矩形线圈尺寸并仿真计算,分析产生磁场的均匀区域。针对磁力仪的需求,选择合适的材料制作实物,并对缠制好的矩形线圈进行测量,符合预期对均匀性的要求。5、分析了铯原子磁力仪的灵敏度及共振光谱的谱线宽度会对磁力仪的影响,针对不同磁场情况下,研究了磁场对Cs原子D1线共振光谱的影响以及磁场与共振谱线线宽的关系,研究表明:外磁场的变化能够导致闭合跃迁Fg=3→Fe=4对应极化谱线宽的展宽以及零点的频移;另外还指出,磁场强度的增大还可以导致极化谱的相对强度的衰减。本章为后续对大磁场的测量打下基础,分析可能出现的谱线特征,并且得到相应结论。本文的主要创新性成果包括:1、考虑到磁力仪灵敏度受磁共振光谱线宽及磁场均匀性的双重影响,针对共振光谱及磁场均匀性分别进行研究;2、打破传统对亥姆霍兹线圈产生磁场均匀性的局限性,尝试使用矩形线圈组,结果显示产生的磁场更加均匀,在铯泡范围内变化不超过1%;3、对于磁屏蔽装置内的强磁环境,考虑非线性塞曼效应的影响,深入研究磁共振光谱线宽与磁场均匀性关系。
[Abstract]:The precise measurement of the weak magnetic field, as an important means to study the shape and properties of the magnet, can be used in the practical application, such as the measurement of the biological magnetic field in the medicine, the study of the topography in the geological survey, the detection of the material defects in the process and the exploration of the mineral oil and gas, It plays an important role in the field of underwater magnetic target location and archaeology. The types of magnetometers which are widely used are magnetic flux gate magnetometer, nuclear precession magnetometer, optical pump magnetometer and superconducting magnetometer, and the sensitivity of these magnetometers is high. In that aspect of the magnetic sensitivity of a magnetometer, we mainly measure the relationship between the line width and the magnetic field of the atomic magnetic resonance spectral line. The magnetic field itself can be influenced by the factors such as space, temperature and humidity. Even in the steady-state environment, the magnetic field can change over time, so we consider the use of the uniform degree of the magnetic field instead of the magnetic field to measure. In this paper, the important application of the magnetometer in a number of fields is described first, the important influence of the relationship between the line width and the magnetic field of the magnetic resonance spectrum on the atomic magnetometer is described, and the main characteristics and the influencing factors of the relevant spectral line type and the line width of the atomic magnetometer are given. then the magnetic field generated by the current-carrying coil of different shapes is simulated and calculated according to the uniformity of the magnetic field required by the research group, and a physical rectangular coil group is manufactured according to the size of the simulation design, and the measurement is carried out; Finally, the magnetic resonance spectrum and the magnetic field homogeneity in the weak magnetic field and the strong magnetic field are studied. The main contents of this paper are as follows:1. The application and significance of the magnetic measurement technology are introduced in detail. The design scheme of several magnetometers is given, and the significance of the magnetic field uniformity to the magnetometer and its sensitivity is analyzed and the main contents of this paper are drawn out. The advantage of selecting Cs atom as a working substance is described, and the basic theory of the magnetic resonance line width involved in this paper is introduced in detail, and the influence of several line widths on the magnetometer is given. In this paper, the characteristics of the magnetic field generated by the traditional current-carrying circular coil and the Helmholtz coil and the system of the cesium atom magnetometer are discussed. The magnetic field generated by the commonly used circular coil and the optimized rectangular coil and the uniformity of the corresponding magnetic field in the experimental part are analyzed systematically. The magnetic field of the current-carrying circular and rectangular coil central part is simulated and analyzed, and the comparison and analysis are carried out, and the conclusion that the rectangular coil is more suitable for the high-sensitivity atomic magnetometer is obtained. The uniform region of the magnetic field is analyzed. according to the requirement of the magnetometer, a suitable material is selected to make a physical object, and the winding rectangular coil is measured to meet the expected uniformity requirement; and 5, the influence of the sensitivity of the cesium atom magnetometer and the spectral line width of the resonance spectrum on the magnetometer is analyzed, In that case of different magnetic field, the influence of the magnetic field on the resonance spectrum of the Cs atom D1 line and the relation between the magnetic field and the line width of the resonance line are studied. An increase in the magnetic field strength may also result in an attenuation of the relative intensity of the polarization spectrum. This chapter lays the foundation for the subsequent measurement of the large magnetic field, analyzes the possible spectral line characteristics, and gets the corresponding conclusion. The main innovative achievements of this paper are as follows:1. Considering the dual effects of the sensitivity of the magnetometer to the width of the magnetic resonance spectral line and the uniformity of the magnetic field, the resonance spectrum and the magnetic field uniformity are studied respectively, and the limitation of the uniformity of the magnetic field generated by the traditional Helmholtz coil is broken, The results show that the magnetic field is more uniform, the change of the magnetic field is not more than 1% in the range of the cesium bubble, and 3. For the strong magnetic environment in the magnetic shielding device, the influence of the non-linear seeman effect is taken into account, and the relationship between the width of the magnetic resonance spectral line and the magnetic field is further studied.
【学位授予单位】：哈尔滨工程大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM936.1

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