博士 / 國立臺灣師範大學 / 物理研究所 / 89 / 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.
CHAPTER 2. Experimental Details ...............4
2.1 Fabrication of the Josephson junction and the dc SQUID .........................................4
2.2 Measurement systems for Josephson junctions and dc SQUIDs ....................................... 5
2.3 Details of the SQUID-based nondestructive evaluation system ........................................12
2.4 Calibration of the nondestructive evaluation system ........................................19
CHAPTER 3. Characteristics of YBCO Josephson Junctions and dc SQUIDs on SrTiO3 Step-edge Substrates ....................................23
3.1 Theories of high-Tc Josephson junctions and dc SQUIDs ........................................23
3.2 YBCO Josephson junctions on SrTiO3 step-edge substrates ....................................28
3.3 YBCO dc SQUIDs fabricated on SrTiO3 step-edge substrates ....................................33
3.4 Summary ...................................44
CHAPTER 4. Application of High-Tc SQUID to Nondestructive Evaluation ....................................45
4.1 Theories for the SQUID-based nondestructive evaluation ....................................45
4.2 Finite element analysis for eddy-current distribution ..................................50
4.3 Eddy-current nondestructive evaluation using a high-Tc SQUID .........................................60
4.4 Summary ...................................78
CHAPTER 5. Conclusion .........................80
REFERENCES ....................................82
APPENDIX ......................................86
ACKNOWLEDGEMENTS ............................. 90
| Identifer | oai:union.ndltd.org:TW/089NTNU0198005 |
| Date | January 2001 |
| Creators | JENG, JEN-TZONG, 鄭振宗 |
| Contributors | HORNG, HERNG-ER, 洪姮娥 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | en_US |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 90 |
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