THE EFFECT OF DIFFERENT LEVELS OF MANGANESE ON MECHANICAL PROPERTIES AND COUPLING

AT FIELDS OF 0 TO 0.3 T, AS USED IN THE SUPERCONDUCTING SUPER COLLIDER INJECTION FIELD, COUPLING BETWEEN NBTI FILAMENTS IN FINE FILAMENTARY COMPOSITES HAS BEEN FOUND TO OCCUR IN SOME MATERIALS. THIS IS PARTICULARLY TRUE WHEN THEINTERFILAMENTARY SPACING FALLS BELOW 0.35 M AND THE MATRIX MATERIAL IS HIGH PURITY COPPER. SEVERAL METHODS OF REDUCING THIS COUPLING HAVE BEEN PROPOSED AND SOME ARE BEING INVESTIGATED. THESE METHODS FALL INTO TWO PRINCIPAL GROUPS: THOSE THAT OPERATE BY SUPPRESSING THE MEAN FREE PATH OF THE ELECTRONS, A ROUTE THAT LEADS TO A HIGH RESISTIVITY SOLID SOLUTION ALLOY MATRIX (E.G. CUNI) AND THOSE THAT EMPLOY ELECTRON-SPIN-FLIP SCATTERING BY SOLUTE IONS CARRYING LOCALIZED MAGNETIC MOMENTS (E.G. MN). IT CAN BE SHOWN THEORETICALLY THAT MN CAN BE AN ORDER OF MAGNITUDE MORE EFFECTIVE THAN NONMAGNETIC SOLUTES IN REDUCING THE PENETRATION DISTANCE OF SUPER ELECTRONS. ALTHOUGH RELATIVELY SMALL PERCENTAGES OF MN IN COPPER MAY BEEFFECTIVE IN REDUCING THE COUPLING, THE EFFECT OF A RANGE OF MN LEVELS ON THE FABRICABILITY OF THESE ALLOYS, PARTICULARLY WHEN IN THE FORM OF A COMPOSITE WITH NBTI, NEEDS TO BE DETERMINED. IN PHASE I, THE EFFECTIVENESS OF MNIN REDUCING COUPLING WILL BE EXPLORED. IN ADDITION, THE EFFECT OF VARIOUS LEVELS OF MN ON THE MECHANICAL AND ELECTRICAL PROPERTIES OF THE CU ALLOYS WITHOUT THE PRESENCE OF NBTI WILL BE DETERMINED. IN PHASE II, FULL SIZE MULTIFILAMENTARY COMPOSITES WILL BE MADE WITH VARIOUS SELECTED CUMN ALLOYS AND THE EFFECTS OBSERVED ON FABRICABILITY, STABILITY, AND COUPLING.