Large field generation with Hot Isostatically Pressed Powder-in-Tube MgB2 coil at 25 K

TL;DR

This paper reports the fabrication and testing of Hot-Isostatic-Pressed MgB2 coils that achieve record critical current densities and magnetic fields at 25 K, suitable for superconducting magnet applications.

Contribution

It introduces the largest reported engineering critical current density in PIT MgB2 wires and demonstrates high-field performance of a 6-layer coil at 25 K.

Findings

Achieved a critical current of over 220 A at 25 K in a 6-layer coil.

Generated magnetic fields up to 1 T at 25 K and 1.6 T at 4 K.

SiC doping improved high-field critical current density to over 10^4 A/cm^2 at 7 T.

Abstract

We present the fabrication and test results of Hot-Isostatic-Pressed (HIPed) Powder-in-Tube (PIT) MgB$_2$ coils. The coils properties were measured by transport and magnetization at different applied fields ($H$) and temperatures ($T$). The engineering critical current ($J_e$) value is the largest reported in PIT MgB$_2$ wires or tapes. At 25 K our champion 6-layer coil was able to generate a field of 1 T at self-field ($I_c >$ 220 A, $J_e \sim 2.8 \times 10^4$ A/cm$^2$). At 4 K this coil generated 1.6 T under an applied field of 1.25 T ($I_c \sim350$ A, $J_e \sim 4.5 \times 10^4$ A/cm$^2$). These magnetic fields are high enough for a superconducting transformer or magnet applications such as MRI. A SiC doped MgB$_2$ single layer coil shows a promising improvement at high fields and exhibits $J_c > 10^4$ A/cm$^2$ at 7 T.