本文探討直流高溫超導SQUID的性質,並對高溫超導SQUID在渦電流非破壞性檢測上之應用的物理問題加以分析研究。首先研究構成高溫超導SQUID的約瑟芬接面之性質,將階梯式接面中晶粒界對SQUID之電壓-磁通特性的影響加以測量並分析。此外,並研究SQUID的圖案設計,尋求增加SQUID磁量計及梯度計之有效面積的方法。在以SQUID做非破壞性檢測的研究上,則是以理論分析及實驗測量來比較並驗證SQUID所測得之缺陷磁場。研究結果發現,缺陷磁場的相位移與缺陷的深度呈線性的關係。因此,藉由測量缺陷磁場的相位移,將可對缺陷的深度作定量的分析及鑑定。
In this work, the characteristics of the high-Tc dc SQUID and the application of the SQUID to nondestructive evaluation were investigated. In probing the characteristics of the Josephson junctions for the SQUID, the first grain boundary was found to dominate the voltage-flux characteristics of the high-Tc dc SQUID with step edge junctions. In addition to the investigation in the junction-related characteristics, the pattern design of the SQUID was studied in order to explore the factors for enhancing the effective area of the directly coupled SQUID magnetometer and gradiometer. In the research for the application of the high-Tc SQUID to nondestructive evaluation, the defect field measured with the SQUID-based nondestructive evaluation system was investigated theoretically and experimentally. The eddy-current distribution of the sample and the defect field of the flaw were calculated with the finite element method. The phase of the defect field was found to exhibit the linear dependence on the depth of the flaw according to the theoretical and the experimental results. Hence, it is possible to find the depth of the flaw quantitatively by analyzing the phase of the defect field over the sample.