MgB₂ cables made of thin wires manufactured by IMD process

Abstract

This paper presents the properties of cables made of thin MgB2 wires with different sheaths manufactured by IMD process. Strong effect of the outer sheath on the Je(B) performance was observed and the best properties were obtained for the strongest Cu sheath. It was found that the transversal and longitudinal cables uniformity affects the critical currents in MgB2 wires made by IMD considerably. We have analyzed the quench dynamics in Rutherford cables with Al+1.5%Al2O3 sheath, when subjected to heat disturbances. Quench triggered in the strands in direct contact with the heater, observing important delays in quench development among strands. Low AC losses were measured for the extra-light Rutherford cable with Ti barrier and Al+1.5%Al2O3 sheath due to an increased barrier resisitivity and surface Al sheath oxidation, which reduces coupling current loss component effectivelly.

Low‐purity Cu and Al sheathed multi‐core MgB2 wires made by IMD process

“…But, figure 5(b) shows the in-field critical current density (J c ) and engineering current density (J e ) at 4.2 K, which are actually 2.02 and 4.1 times higher for 7Cu, respectively. Similar ratios with 2-4 times higher engineering current densities were measured for MgB 2 cables made of thin Cu sheathed IMD wires compared to Al sheathed ones [21]. It indicates that wire deformation in the harder Cu sheath (see table 2) allows to more densify the boron powder than in the mechanically softer Al.…”

Longitudinal uniformity of MgB2 wires made by an internal magnesium diffusion process

“…While area of boron is larger than Mg in as-drawn wire 7CuD (Mg/B = 0.81-0.87, see figure 10(a)), it is in opposite ratio in as-rolled wire 7CuR (Mg/B = 1.21-1.38, see figure 10(b)). It is due to more densified boron powder by rolling deformation in comparison to drawing [22].…”

Transport and structural properties of MgB2/Fe wires produced by redesigning internal Mg diffusion process

“…The core uniformity is also challenging in the production of long IMD wires due to the variations in the packing density of boron powder along the IMD wire, leading to changes in the superconducting properties after heat treatment. Therefore, improving the longitudinal uniformity and J e in IMD wires is essential for large-scale applications [11,[16][17][18][19][20][21].…”