Recovery Velocities for Composite Superconductors

Abstract

In designing large superconducting magnets it is important to have an accurate estimate of the normal zone recovery velocity as a function of the current. To date, there has been only moderate success in calculating the velocity for bare composite superconductors cooled by boiling helium. Keilin et al. [¹] obtained a closed-form expression but assumed constant material properties and no current sharing. Altov et al. [²] included current sharing, but used constant material properties. Miller et al. [³] included current sharing and used temperature-dependent material properties. Most of the authors assume a constant heat transfer coefficient. For insulated wire, good agreement has been obtained using a constant heat transfer coefficient [⁴]. A detailed calculation, containing no adjustable parameters, has been made of the propagation velocities for bare wire [⁵]. In the latter work, which is probably the most thorough to date, it was reported that there was poor agreement between calculated and measured values for bare conductors.

Work supported in part by DOE through MT/FBNML Magnet Technology Development Program.