The influence of tensile stress on the critical current of filamentary Nb3Sn magnet conductor

The design and construction of an experiment to measure the influence of tensile stress on the critical current properties of filamentary Nb3Sn composites is described. Special attention has been paid to obtaining design data useful for coil construction. The results obtained for one type of composite show that the critical current is reduced by tensile stress. At stresses up to 240-250MN/m²(ε~ 0.5%) the effect is reversible, being about 5-10% of the original critical current. Beyond this level permanent degradation occurs. The deterioration is progressive rather than catastrophic. The implications for magnet construction are discussed.