Finite-Element Analysis of Transverse Compressive and Thermal Loads on Nb3Sn Wires With Voids

High-field superconducting magnets play a very important role in many large-scale physics experiments, particularly particle colliders and fusion confinement devices such as Large Hadron Collider (LHC) and International Thermonuclear Experimental Reactor (ITER). The two most common superconductors used in these applications are NbTi and Nb
₃
Sn. Nb
₃
Sn wires are favored because of their significantly higher J
_c
(critical current density) for higher field applications. The main disadvantage of Nb
₃
Sn is that the superconducting performance of the wire is highly strain sensitive and it is very brittle. This strain sensitivity is strongly influenced by two factors: plasticity and cracked filaments. Cracks are induced by large stress concentrators that can be traced to the presence of voids in the wire. We develop detailed 2-D and 3-D finite-element models containing wire filaments and different possible distributions of voids in a bronze-route Nb
₃
Sn wire. We apply compressive transverse loads for various cases of void distributions to simulate the stress and strain response of a Nb
₃
Sn wire under the Lorentz force. This paper improves our understanding of the effect voids have on the Nb
₃
Sn wire's mechanical properties, and in so, the connection between the distribution of voids and performance degradation such as the correlation between irreversible strain limit and the void-induced local stress concentrations.