A MORE ECONOMICAL LOW LOSS NB3SN FOR PULSED FIELD APPLICATIONS, MADE BY A MODIFIED "INTERNAL TIN" PROCESS.

THE AIM OF THE PROPOSED WORK IS TO MODIFY THE "INTERNAL TIN"PROCESS TO PROVIDE AN ECONOMICAL, HIGH JC, NB3SN MATERIAL WITH LOW LOSSES IN PULSED FIELD APPLICATIONS. IT WILL BE MANUFACTURED IN THE UNITED STATES TO COMPETE WITH THE OVERSEAS SUPPLIERS OF BRONZE PROCESSED MATERIAL WHICH HAS A HIGHER COST AND LOWER PERFORMANCE CAPABILITY. IGC/ASI HAS BEEN DEVELOPING THE INTERNAL TIN PROCESS FOR THEMANUFACTURE OF NB3SN FOR MANY YEARS AND RECENTLY HAS IMPROVED THE DESIGN AND FABRICATION PROCEDURES TO INCREASE THE PIECE LENGTH AND FURTHER ENHANCE THE PROPERTIES. THE LOSSES IN PULSED APPLICATIONS HAVE NOW BEEN REDUCED TO THE POINT WHERE THOSE DUE TO THE PRESENCE OF SUPERCONDUCTOR ON THE INSIDE OF THE BARRIER ARE APPARENT AS A SIGNIFICANT PART OF THE OVERALL LOSSES. IT IS THE PURPOSE OF THE WORK PROPOSED HERE TO REDUCE THESE BARRIER LOSSES. THE STRAIGHT REPLACEMENT OF NB BY TA OR V, WHILE IT MAY SOLVE THE ELECTRICAL PROBLEMS, WILL INCREASE THE COST OF THE CONDUCTOR. IT MAY ALSO BE DIFFICULT TO ACHIEVE THE REPLACEMENT, PARTICULARLY WITH TA, USING THE CONVENTIONAL EXTRUSION AND HIP'ING METHODS OF MAKING THE STABILIZER. WE WILL, THEREFORE, EXPLORE THREE NEW WAYS TO INTRODUCE TA AND V BARRIERS IN AN ECONOMICAL MANNER, SO AS TO KEEP THE COST OF THE NB3SN PRODUCT TO A MINIMUM AND IMPROVE THE MATERIAL'S PULSED PERFORMANCE, WITHOUT SACRIFICING ON JC AND PIECE LENGTH. THREE APPROACHES WILL BE TRIED IN PHASE I. A. ROLLED UP AND OVERLAPPED TANTALUM FOIL INSIDE A COPPER STABILIZER TUBE. B. ROLLED UP AND OVERLAPPED TANTALUM FOIL INSIDE A COPPER TUBE, HIP'D AFTER ASSEMBLY. C. A NB FOIL WITH V STRIPS ATTACHED, ROLLED UP AND OVERLAPPED INSIDE A COPPER TUBE. FOR REASONS OF COST AND TIME WE WILL CONCENTRATE IN PHASE I WORK ON THE BARRIERS USING THE RELATIVELY LOW COST CU AND CUNI AS CORE MATERIALS. IN PHASE II WE WILL REPLACE THESE CORES BY SUPERCONDUCTING SUBELEMENTS AND SCALE UP THE PROCESS.