Future high energy physics colliders could benefit from accelerator magnets based on high-temperature superconductors, which may reach magnetic fields of up to 45 T at 4.2 K, twice the field limit of the two Nb-based superconductors. Bi₂Sr₂CaCu₂O_8-x (Bi-2212) is the only high-T _c cuprate material available as a twisted, multifilamentary and isotropic round wire. However, it has been hitherto unclear how an accelerator magnet can be fabricated from Bi-2212 round wires and whether high field quality can be achieved. This paper reports on the first demonstration of high current Bi-2212 coils using Rutherford cable based on a canted-cosine-theta (CCT) design and an overpressure processing heat treatment. Two Bi-2212 CCT coils, BIN5a and BIN5b, were made from a nine-strand Rutherford cable. Their electromagnetic design is identical, but they were fabricated differently: both coils underwent heat treatment in their aluminum–bronze mandrels, but unlike BIN5a that was impregnated with epoxy in its reaction mandrel, the conductor of BIN5b was transferred to a 3D printed Accura Bluestone mandrel after the heat treatment, a process attempted here for the first time, and was not impregnated. BIN5a reached a peak current of 4.1 kA with a self-field of 1.34 T in the bore. This corresponds to a wire engineering current density (J _e) of 912 A mm⁻², which is two times that of BIN2-IL, a previous Bi-2212 CCT coil fabricated at LBNL, which used a six-around-one cable processed with the conventional 1 bar pressure melt processing. On the other hand, BIN5b reached 3.1 kA. The coils exhibited no quench training. All the quenches were thermal runaways that occurred at the same location. In addition, we report on the field quality and ramp-dependent hysteresis measurements taken during the test of BIN5a at 4.2 K. Overall, our results demonstrate that the CCT technology is a route that should be further investigated for making high field, potentially quench training free dipole magnets with Bi-2212 cables.

未来的高能物理对撞机可能会受益于基于高温超导体的加速器磁体，该加速器磁体在4.2 K时的磁场强度最高可达45 T，是两个Nb基超导体的磁场极限的两倍。Bi ₂ Sr ₂ CaCu ₂ O _8-x（Bi-2212）是唯一的高T _c铜酸盐材料有双绞，多丝和各向同性的圆线。然而，迄今还不清楚如何由Bi-2212圆线制造加速器磁体以及是否可以实现高磁场质量。本文报道了使用卢瑟福电缆进行的首次大电流Bi-2212线圈演示，该线圈基于倾斜余弦角（CCT）设计和超压处理热处理。两个Bi-2212 CCT线圈BIN5a和BIN5b由一根九股卢瑟福电缆制成。它们的电磁设计相同，但制造方式不同：两个线圈均在其铝青铜心轴中进行了热处理，但与在反应心轴中浸有环氧树脂的BIN5a不同，BIN5b的导体转移到了3D打印的Accura蓝宝石心轴中热处理后 此过程是第一次尝试在这里进行，没有被浸渍。BIN5a在孔中的自电场为1.34 T时达到了4.1 kA的峰值电流。这对应于电线工程电流密度（J _e）为912 A mm ^-2，是BIN2-IL的两倍，BIN2-IL是在LBNL制造的先前Bi-2212 CCT线圈的两倍，该线圈使用经过六圈一根的电缆进行常规1 bar压力熔融处理。另一方面，BIN5b达到3.1kA。线圈没有淬火训练。所有的淬火都是在同一位置发生的热失控。此外，我们报告了在BIN5a在4.2 K的测试过程中进行的场质量和与斜坡有关的磁滞测量。总体而言，我们的结果表明，CCT技术是进行高场，潜在淬火培训应进一步研究的途径带有Bi-2212电缆的免费偶极磁体。