超导性.第1部分:临界电流测量.铌-钛复合超导体的临界直流电流

[中文适用范围]： IEC 61788 的这一部分涵盖了用于确定铜/超导体比率大于 1 的 Cu/Nb-Ti 复合超导体或具有铜/超导体比率大于0.9，铜合金(Cu-Ni)/超导体比率大于0.2，其中Nb-Ti超导丝的直径大于1μm。附录 C 中描述了 Cu/Cu-Ni/Nb-Ti 的变化。Cu-Ni 使用了标准的所有主要部分，但附录 C 中列出的例外情况除外，这些例外情况取代了（并且在某些情况下相反）正文中的一些步骤。该方法适用于在标准测试条件下且磁场小于或等于上临界磁场 0.7 时临界电流小于 1 000 A 且 n 值大于 12 的超导体。测试过程中将测试样品浸入已知温度的液氦浴中。测试导体为整体结构，横截面积小于2mm2的圆形或矩形。该测试方法中使用的样本几何形状是感应线圈样本。本标准给出了例行试验所允许的与本试验方法的偏差以及其他具体限制。临界电流高于 1 000 A 或横截面积大于 2 mm2 的测试导体可以用本方法进行测量，预计不确定性会增加，自场效应会更显着（见附件 B）。其他更专业的样本测试几何形状可能更适合较大的导体测试，为简单起见并保留较低的不确定性，本标准已省略这些几何形状。本标准给出的测试方法经过适当修改后预计适用于其他超导复合线材。 [外文原描述]： This part of IEC 61788 covers a test method for the determination of the d.c. critical current of either Cu/Nb-Ti composite superconductors that have a copper/superconductor ratio larger than 1 or Cu/Cu-Ni/Nb-Ti wires that have a copper/superconductor ratio larger than 0,9 and a copper alloy (Cu-Ni)/superconductor ratio larger than 0,2, where the diameter of Nb-Ti superconducting filaments is larger than 1 micrometre. The changes for the Cu/Cu-Ni/Nb-Ti are described in Annex C. The Cu-Ni uses all of the main part of the standard with the exceptions listed in Annex C that replace (and in some cases are counter to) some of the steps inthe main text. This method is intended for use with superconductors that have critical currents less than 1 000 A and n-values larger than 12, under standard test conditions and at magnetic fields less than or equal to 0,7 of the upper critical magnetic field. The test specimen is immersed in a liquid helium bath at a known temperature during testing. The test conductor has a monolithic structure with a round or rectangular cross-sectional area that is less than 2 mm2. The specimen geometry used in this test method is an inductively coiled specimen. Deviations from this test method that are allowed for routine tests and other specific restrictions are given in this standard. Test conductors with critical currents above 1 000 A or cross-sectional areas greater than 2 mm2 could be measured with the present method with an anticipated increase in uncertainty and a more significant self-field effect (see Annex B). Other, more specialized, specimen test geometries may be more appropriate for larger conductor testing which have been omitted from this present standard for simplicity and to retain a lower uncertainty. The test method given in this standard is expected to apply to other superconducting composite wires after some appropriate modifications.