Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan.
Department of Physics, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan.
Rev Sci Instrum. 2023 Jul 1;94(7). doi: 10.1063/5.0147438.
To generate long-duration pulsed magnetic fields with low energy consumption, we present a practical setup that implements an electromagnet made of high-purity copper (99.9999%). The resistance of the high-purity copper coil decreases from 171 mΩ (300 K) to 19.3 mΩ (77.3 K) and to below ∼0.15 mΩ (4.2 K), indicating a high residual resistance ratio of 1140 and a substantial reduction in Joule loss at low temperature. Using a 157.5 F electric-double-layer-capacitor bank with a charged voltage of 100 V, a pulsed magnetic field of 19.8 T with a total field duration of more than 1 s is generated. The field strength of the liquid helium-cooled high-purity copper coil is approximately double that of a liquid nitrogen-cooled one. The low resistance of the coil and the resultant low Joule heating effect explain the improvements in accessible field strength. The low electric energy used for field generation warrants further investigation on low-impedance pulsed magnets consisting of high-purity metals.
为了以低能耗产生长持续时间的脉冲磁场，我们提出了一种实用的设置，该设置实现了由高纯度铜（99.9999%）制成的电磁铁。高纯度铜线圈的电阻从 171 mΩ（300 K）降至 19.3 mΩ（77.3 K），再降至约 0.15 mΩ（4.2 K），表明高残余电阻比为 1140，低温下焦耳损耗大幅降低。使用带有 100 V 充电电压的 157.5 F 双电层电容器组，可产生 19.8 T 的脉冲磁场，总场持续时间超过 1 s。液氦冷却的高纯度铜线圈的磁场强度大约是液氮冷却的两倍。线圈的低电阻和由此产生的低焦耳加热效应解释了可达到的场强的提高。用于产生场的低电能需要进一步研究由高纯度金属组成的低阻抗脉冲磁铁。
