Field and Strain Dependence of the Critical Current and the n-value for an Internal-tin Processed $Nb_3Sn$ Strand

내부확산법으로 제조된 $Nb_3Sn$ 초전도 선재의 임계전류 및 n-값의 자장, 변이 의존성

Detailed field and strain dependence of the critical current and the n-value for an internal-tin processed $Nb_3Sn$ strand have been measured. Both the compressive and tensile strain is applied reversibly using Walter spiral probe made of BeCu up to 0.73 %. There is a correlation between the critical current and the n-value for the $Nb_3Sn$ strand studied in this work and the field dependence of the n-value is in agreement with a recent empirical formula. It was further shown that the critical current can be reasonably well fitted by the scaling law based on strong-coupling theory of superconductivity using the relation between the critical current and the n-value.