Effects of the Heater Winding on the Stability Tests of the Superconductor

In order to measure the minimum propagating current of the composite superconductor, heater wire is usually wound around the superconductor to heat it up and make a small normal zone. Usually this heater wire is thermally insulated from helium by epoxy resin and these thermal insulation seems to affect on the steady state stability of the superconductor. A simple graphical scheme have been presented for incorporating heat transfer and heat generation characteristics into calculation of the stability of superconductive composite conductors with local thermal insulation, modifying the equal area method presented by Maddock et al. The effects of the local thermal insulation on the steady state stability of composite superconductors are discussed by this graphical scheme. It is shown that the minimum propagating current of the composite superconductor with the local thermal insulation is the same as that of the conductor without the thermal insulation but there are the thermal equilibrium current below the minimum propagating current.