Role of internal gases and creep of Ag in controlling the critical current density of Ag-sheathed Bi2Sr2CaCu2Ox wires
Role of internal gases and creep of Ag in controlling the critical current density of Ag-sheathed Bi2Sr2CaCu2Ox wires
复制标题
DOI：
10.1063/1.4807795
复制
发表时间：
2013-01
影响因子：
3.2
通讯作者：
T. Shen;A. Ghosh;L. Cooley;J. J. T. Division-J.;F. Lab;Batavia;Il;Superconducting Magnet Division;B. Lab;Brookhaven;Ny;Applied Superconductivity Center;National High Magnetic Field Laboratory;Florida State University;Tallahassee;Fl
中科院分区：
文献类型：
--
作者：
T. Shen;A. Ghosh;L. Cooley;J. J. T. Division-J.;F. Lab;Batavia;Il;Superconducting Magnet Division;B. Lab;Brookhaven;Ny;Applied Superconductivity Center;National High Magnetic Field Laboratory;Florida State University;Tallahassee;Fl
在20 T和4.2 K下，当试样长度为几厘米时，Ag包套多芯Bi_2Sr_2CaCu_2 O_x（Bi-2212）圆丝可获得大于500 A/mm ~ 2的高工程临界电流密度JE。然而，在几米长的Bi-2212导线以及缠绕成线圈的较长段中，JE（20 T）很少超过200 A/mm 2。此外，长长度的线通常在熔融加工后表现出Bi-2212泄漏的迹象，这在短的开口端样品中很少发现。我们使用质谱法研究了现有技术的管中粉末（PIT）Bi-2212线的JE的长度依赖性和在熔融加工期间由它们释放的气体，证实了JE随长度的降解是由于在升高的温度下由高内部气体压力产生的线溶胀[A. Malagoli等人，Supercond. Sci. Technol.24，075016（2011）和A. Malagoli等人，Supercond. Sci. 26，055018（2013）]。我们进一步模拟了Bi-2212线中的气体输运，并研究了临界阶段的线膨胀。
High engineering critical current density JE of > 500 A/mm2 at 20 T and 4.2 K can be regularly achieved in Ag-sheathed multifilamentary Bi2Sr2CaCu2Ox (Bi-2212) round wire when the sample length is several centimeters. However, JE(20 T) in Bi-2212 wires of several meters length, as well as longer pieces wound in coils, rarely exceeds 200 A/mm2. Moreover, long-length wires often exhibit signs of Bi-2212 leakage after melt processing that are rarely found in short, open-end samples. We studied the length dependence of JE of state-of-the-art powder-in-tube (PIT) Bi-2212 wires and gases released by them during melt processing using mass spectroscopy, confirming that JE degradation with length is due to wire swelling produced by high internal gas pressures at elevated temperatures [A. Malagoli et al. Supercond. Sci. Technol. 24, 075016 (2011) and A. Malagoli et al. Supercond. Sci. Technol. 26, 055018 (2013)]. We further modeled the gas transport in Bi-2212 wires and examined the wire expansion at critical stage...