NONINTRUSIVE PHOTOACOUSTIC CHARACTERIZATION OF CRITICAL PROPERTIES IN HIGH TC SUPERCONDUCTING MATERIALS

THE RECENT DISCOVERY OF NEW HIGH TEMPERATURE SUPERCONDUCTOR SYSTEMS HAS CREATED A NEED TO DEVELOP COMPATIBLE MEASUREMENTTECHNIQUES TO CHARACTERIZE THE ELECTRICAL, STRUCTURAL, ACOUSTIC AND OPTICAL PROPERTIES OF THESE MATERIALS. ALTHOUGH MANY STANDARD METHODS OF MEASURING CONVENTIONAL SUPERCONDUCTING MATERIALS CAN BE ADAPTED TO NEW HIGH TC SUPERCONDUCTOR SYSTEMS, EFFECTIVE MEASUREMENT OF CRITICAL PROPERTIES IS DIFFICULT. CONVENTIONAL ACOUSTIC TECHNIQUES TO MEASURE THE PHYSICAL PROPERTIES OF SUPERCONDUCTING MATERIALS NORMALLY REQUIRE CONTACT BETWEEN THE SENSOR AND THE SUPERCONDUCTING MATERIAL UNDER TEST. THIS PROPOSAL SUGGESTS THE USE OF NONCONTACTING LASER-BASED ULTRASONICS ASA MEANS OF ACCURATE, NON-INTRUSIVE MEASUREMENT OF THE ELECTRONIC, VIBRATIONAL AND OPTICAL PROPERTIES OF NEW HIGH TC SUPERCONDUCTING MATERIALS. THE PHASE I RESEARCH OBJECTIVES INCLUDE STUDY OF HIGH-ENERGY LASER-INDUCED PHOTOACOUSTIC EFFECTS, EVALUATION OF LASER-BASED ULTRASONIC SYSTEM PARAMETERS, INTEGRATION OF SPECKLE-BASED ACOUSTIC DETECTION SUBSYSTEM, ASSESSMENT OF PHOTOACOUSTIC PARAMETERS AND DESIGN OF A PROOF-OF-CONCEPT NONCONTACTING PHOTOACOUSTIC SENSOR USING REMOTE EXCITATION BY LASERS AND REMOTE SENSING BY INTERFEROMETERS. SUCCESSFUL COMPLETION OFTHESE OBJECTIVES WOULD RESULT IN A RESEARCH TECHNIQUE FOR IMPROVED MATERIAL CHARACTERIZATION IN SUPERCONDUCTING PEROVSKITE STRUCTURES IN ENVIRONMENTS AT LOWER THAN ROOM TEMPERATURE. THE SIGNIFICANCE OF THE PROPOSED PROGRAM IS THE DEVELOPMENT OF NONCONTACT AND VERSATILE ULTRASONIC MONITORING SYSTEM FOR FABRICATION PROCESSES AND OF ACOUSTIC VIBRATIONAL MODE MEASUREMENTS FOR SUPERCONDUCTING DEVICE PERFORMANCE. IT IS EXPECTED THAT THE PROPOSED TECHNOLOGY WILL ENHANCE THE COMMERCIAL USE OF SUPERCONDUCTING ELECTRONIC DEVICES, SYSTEMS AND HIGH-SPEED COMPUTERS.