高温超导材料交流损耗测试方法及应用研究

发布时间：2018-01-14 05:28

本文关键词：高温超导材料交流损耗测试方法及应用研究　出处：《兰州大学》2017年博士论文　论文类型：学位论文

【摘要】：超导体与传统导体的本质区别在于其所具有的无阻载流特性,正是这一特征吸引着众多研究人员的目光,在新型超导材料制备、物理机制揭示及工程实际应用领域开展了不懈探索,取得了重要的研究成果。以具有实用化前景的非理想二类超导体为例,当其承载不超过临界电流的直流电流时,超导体内部没有任何能量损耗,这时该超导体处于稳定运行状态。然而,在超导体实际应用过程中,承载电流变化或所处环境电磁场的变化均不可避免,会给超导体带来能量损耗,通常将其定义为交流损耗。交流损耗的产生会造成超导体内部局部温度升高并伴随着钉扎性能和临界电流的降低,给超导装置带来巨大的安全隐患。如2008年欧洲强子对撞机巨型超导磁体的爆炸事故就是源于超导材料局部失超而引起液氦蒸发所致,造成历时14个月,耗资6千万美元的停机整修。因此,超导材料的交流损耗特征已成为超导器件安全性设计的重要参数之一,相应的超导材料交流损耗的测试方法研究引起了众多学者的关注。另外,对于临界温度高于液氮沸点的氧化物陶瓷类高温超导材料,制备和应用过程中微裂纹的出现不可避免。因此,对于含裂纹超导材料的交流损耗特征也成为前沿问题之一,主要原因在于在裂纹尖端屏蔽电流分布的复杂性导致该区域的能量损耗难以采用传统的方法进行测试。为此,本博士学位论文在开展传统绝热测温法的关键参数、测试误差等研究的基础上,首次获得了高温超导材料焊接接头的交流损耗特征及其内部电流和电阻的变化规律。通过对该方法测试原理的研究将其测试功能扩展,首次得到了含裂纹超导材料的交流损耗。最后采用电测法对这类样品的交流损耗也进行了测试,对比结果表明本文所提出的绝热测温升法的可靠性。主要工作如下:首先,详细介绍了自行组建的绝热测温升法和电测法实验测试系统。接着采用这两种测试方法对YBCO涂层导体的交流损耗进行了测试,并把实验结果与Norris理论计算结果进行了比较,验证了本文自行组建的两套交流损耗测试系统的可靠性。然后针对绝热测温升法的实验影响因素进行了详细研究,获得了测试临界电流和校正曲线所需的最优直流电加载速度和加载区间,并通过对绝热测温升法的实验误差分析得到了最优电流加载时间47s。其次,采用绝热测温升法对YBCO焊接接头和完整超导样品在不同排布方式下的交流损耗进行了测量。通过对超导焊接接头和完整样品的交流损耗进行比较发现接头长度对其损耗影响较小,并且超导接头处的发热量不会影响整个装置运行的稳定性。同时提出了一种超导焊接接头电流分布的实验测试方法和理论模型,其理论计算与实验结果相吻合表明本文提出的理论模型的正确性。通过对实验原理的研究实现了传统绝热测温升法测试功能的扩展,并以此获得了含裂纹超导体交流损耗的特征。实验结果表明随着裂纹长度的增加,裂纹对完整超导样品损耗功率的影响急剧增大,严重影响超导装置运行的安全性。最后,采用电测法对受横向载荷作用和含裂纹超导样品的交流损耗进行了测量。弄清了横向压应力对超导样品交流损耗的影响规律,并将其与轴向拉伸对样品交流损耗的影响进行了对比。随后采用电测发对含裂纹超导样品交流损耗进行测试,并与之前的绝热测温升法结果进行对比。结果显示这两种方法获得的交流损耗随着加载电流和裂纹长度的变化规律一致,证实了扩展后绝热测温升法的可靠性。
[Abstract]:The essential difference between superconductor and traditional conductor is no resistance current carrying its characteristic, it is this feature attracts many researchers attention in the new superconducting materials preparation, physical mechanism and actual application in the project areas to carry out the unremitting exploration and made important research results. With the practical prospects the non ideal two superconductors, for example, when the carrying DC current does not exceed the critical current, the superconductor without any loss of energy, then the superconductor in steady state operation. However, in the superconductor in practical application process, changes in current carrying or changes in environment field are inevitable, will bring the energy loss to the superconductor, usually defined as the AC loss. AC losses generated will cause local temperature superconductors with reduced nail proof performance and the critical current, to super The guide device is a huge security risks. As of 2008 the European Hadron Collider giant superconducting magnet explosion is derived from superconducting material local quench caused by evaporation of liquid helium, which lasted 14 months, at a cost of $60 million renovation shutdown. Therefore, the AC loss characteristics of superconducting materials has become one of the important parameters of superconducting device safety design and Research on the test method of AC loss of the corresponding superconducting materials has attracted attention of many scholars. In addition, the critical temperature is higher than the boiling point of liquid nitrogen oxide ceramic superconducting materials, preparation and application of micro cracks appear inevitable. Therefore, it has become a key problem for one of the characteristics of AC losses of superconducting materials with cracks the main reason lies in the complexity, crack tip shielding current distribution leads to energy loss in the region is difficult to use the traditional method. For the test. Therefore, this dissertation carried out the key parameters in the traditional adiabatic temperature measurement method, based on test error and so on, for the first time variation of welded joint of high temperature superconducting materials AC loss characteristics and current and internal resistance. Through the research on the method of testing the principle of the test function expansion, for the first time the AC losses of superconducting materials with crack. Finally the AC loss of electric measurement on this kind of samples were also tested, comparison results show that the reliability of the adiabatic temperature rise method proposed in this paper. The main work is as follows: first, introduces the temperature rise to the formation of adiabatic method and electric measurement test system. Then using the two kinds of test methods for AC loss of YBCO coated conductors were tested, and the experimental results and theoretical calculation results of Norris were compared to verify the self The reliability for formation of two sets of AC loss test system. Then according to the affecting factors of temperature rise of adiabatic method were studied to obtain optimal critical current test and calibration curve for DC loading speed and loading range, and through the analysis of test error on the adiabatic temperature rise measurement method to get the optimal loading current the second time 47s., the adiabatic temperature rise of AC losses of joint and complete superconducting samples in different arrangements of YBCO welding was measured. The AC loss of HTS welded joints and complete samples were compared with that joint length has little influence on the heat loss, and will not affect the stability of superconducting junction device operation. At the same time put forward a superconducting welded joint current distribution test method and theoretical model, the theoretical calculation and experimental results of kiss He showed the correctness of the theoretical model proposed in this paper. Through the research on the extension principle of the traditional adiabatic temperature rise test function, and in order to get the characteristics of the cracked superconductor AC loss. The experimental results show that with the increase of the crack length, the crack on the end effect of full superconducting sample power loss increases rapidly. Seriously affect the safety operation of superconducting devices. Finally, the electrometric method of transverse load and crack of superconducting samples of AC losses were measured. To ascertain the transverse compressive stress on AC losses of superconducting samples the influence rule, and compares them with axial strain on the samples. Then the influence of AC loss the electrical measurement test of hair crack superconducting samples of AC losses, and temperature rise before the adiabatic method were compared. The result shows that AC loss obtained by these two methods The reliability of the extended adiabatic temperature measurement method is confirmed by the uniform variation of the load current and the crack length.

【学位授予单位】：兰州大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TM26

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