Minimum Quench Energy Of Nb$_3$Sn Wires With High Specific Heat Tape

TL;DR

This study explores increasing the specific heat of Nb3Sn accelerator magnet wires using composite tapes to enhance quench energy and reduce training issues.

Contribution

It demonstrates the feasibility of using high-Cp composite tapes wrapped around or inserted into Rutherford cables to improve quench energy in Nb3Sn wires.

Findings

MQE increased by 2.5 times at 90% I_c and 15 T with Cu/Gd2O2S tapes.

High-Cp tapes can be integrated in various configurations around the cable.

Potential to reduce magnet training by limiting temperature rise during operation.

Abstract

A major problem of state-of-the-art Nb$_3$Sn accelerator magnets is their long training due to thermo-mechanical perturbations. Increasing the specific heat, $C_p$, of the Rutherford cable would reduce and/or eliminate training by limiting the coils temperature rise. This paper studies feasibility of increasing the $C_p$ of Rutherford-type cables by using thin composite Cu/$Gd_2$O$_3$ and Cu/$Gd_2$O$_2$S tapes produced by Hyper Tech Research, Inc. The tape can be either wrapped around the cable, placed on the cable wide faces under the insulation, and/or inserted as a core. Wire samples outfitted with these high-$C_p$ ribbons, or tapes, were prepared and tested at FNAL for their Minimum Quench Energy (MQE). At 90%I$_c$ and 15 T, the average gain of MQE of the Nb$_3$Sn wire soldered to the Cu/$Gd_2$O$_2$S 55 micrometer thick ribbon was 2.5, and further increased at larger transport currents.