Liquid helium-cooled high-purity copper coil for generation of long pulsed magnetic fields

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 m Omega (300 K) to 19.3 m Omega (77.3 K) and to below similar to 0.15 m Omega (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.

Automated summary

In order to generate long-duration pulsed magnetic fields with low energy consumption, a practical setup using an electromagnet made of high-purity copper (99.9999%) is presented. The resistance of the high-purity copper coil significantly decreases at low temperatures, resulting in a high residual resistance ratio and a reduction in Joule loss. Through the use of an electric-double-layer-capacitor bank, a pulsed magnetic field with a total duration of over 1 s and a field strength of 19.8 T is generated. The low resistance of the coil and low Joule heating effect explain the improvements in accessible field strength, making it suitable for further investigation on low-impedance pulsed magnets consisting of high-purity metals.