Multifilamant Nb<inf>3</inf>Sn multistrand cable performance using supercritical helium

Abstract

We have measured the effect of change of supercritical helium flow on stability of a cabled multifilamentary (MF) Nb <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> Sn conductor. We varied the flow of supercritical He through the cable and measured the ability of the cable to absorb single pulses of magnetic energy while the cable was carrying about 73% of its measured critical current in an applied 9.0T magnetic field. We have quantified the pulse energies in terms of the thermodynamic behavior of the helium fluid within the cable. Varying fluid mass flow rate <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">G</tex> in the range <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0 \leq G \leq 36</tex> g/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> s, we have observed stability of the MF Nb <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> Sn cable which is apparently as independent of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">G</tex> as were previously investigated MF NbTi cables. Thus our present and previous findings in 3m length MF superconductor cables suggest the dominance by flow independent heat transfer mechanisms, rather than the flow generated turbulence previously considered dominant.