STUDY OF FILAMENT INSTABILITY IN MULTIFILAMENTARY NBTI/CU COMPOSITES

CRITICAL CURRENT DENSITIES (JC) AS HIGH AS 3500 A/MM2 AT 5 TESLA HAVE BEEN DEMONSTRATED IN EXPERIMENTAL NBTI SUPERCONDUCTOR SAMPLES. IN PRACTICAL MULTIFILAMENTARY NBTI/CU SUPERCONDUCTORS, HOWEVER, THIS HIGH JC HAS NOT BEEN ACHIEVED SO FAR DUE TO FILAMENT INSTABILITY. THE INSTABILITY LEADING TO FILAMENT SAUSAGING AND EVENTUAL FRACTURING HAS BECOME A MAJOR HURDLE IN THE RECENT DEVELOPMENTAL CONDUCTORS CONTAINING 2.5 TO 5 MICROMETER FILAMENTS. THE PROPOSED RESEARCH WILL FOCUS EFFORTS TO IDENTIFY THE FACTORS RESPONSIBLE FOR THE ONSET OF INSTABILITY. GEOMETRICAL PARAMETERS AND MATERIAL CHARACTERISTICS ARE CONSIDERED MOST CRITICAL AND THESE WILL BE INVESTIGATED. MODEL COMPOSITES WILL BE DESIGNED AND PROCESSED TO FINAL SIZE. THE FINISHED PRODUCT WILL HAVE NBTI FILAMENTS IN THE SIZE RANGE OF 2 TO 10 MICROMETERS SUITABLE FOR THE SUPERCONDUCTING SUPER COLLIDER (S.S.C.). THE DETAILS OF THE COMPOSITE DESIGN AND PROCESSING WILL BE BASED UPON THE MOST UP-TO-DATE UNDERSTANDING OF THE METAL FLOW IN COMPOSITES AND OF METALLURGICAL/MICROSTRUCTURAL REQUIREMENTS FOR OPTIMIZING JC.