Stability criteria for cable-in-conduit superconducting cables for steady or slow pulse operation

摘要

In the design of CIC conductors using NbTi or Nb3Sn strands cooled with supercritical He, the choice of stability criteria for near steady state operation presents a problem. The disturbances are small, under 10 mJ/cm3of cable material, too small for design significance. The main parameters affected by the choice of stability criteria are temperature margin and Cu:nonCu ratio, both of which strongly affect cable cost and overall current density. Methods quantifying the copper required for stability have been elementary, mostly using cryogenic stability (the well-cooled condition). Recent experimental and analytical work on the electric field achieved before quench Eq suggest a more exact method. Cable quench is modeled by a simple stability simulation, including copper conduction and the superconducting transition. A heat transfer coefficient is derived from ITER model coil data. As an example it is applied to conductor design for the ITER fusion reactor magnets.