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I n the framework of the development of superconducting coils for the stellarator Wendelstein 7-X, the reduction of the critical current due to thermal treatment was investigated. During production steps like the extrusion of the Aljacket onto the superconducting cable and also during welding and soldering, heat flux into the NbTi-strands occurs. For optimized NbTi-strands a degradation of the critical current was expected. The results of measurements of the critical current of a n annealed N b T i multifilamentary superconductor at 4.2 K in the field range from 2 T to 10 T are presented. The commercially availahle conductor has been annealed at various temperatures up to 600 OC and times up to 120 s in order to simulate the conditions during such production steps. Special attention is paid to the shape of the voltage-current transition which is characterized on the one hand hy a power law and on the other hand by an exponential function.

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