Characterizing thermal runaway in HTS current leads

Following a brief review of the many issues pertinent to HTS current lead design, we describe the performance of a pair of 1500 A HTS current leads during the transient warm-up following a loss of intercept cooling. Results describing the subsequent temperature evolution are provided both from experimental measurements and from an associated ANSYS model. The study confirms that HTS current leads must be analyzed on a system basis-incorporating the thermal and electrical characteristics of all components-to provide useful information for the end user. A performance contrast is provided between conduction-cooled and convection-cooled modes. It is found that when heat generation in the HTS conductor exceeds convective cooling by a factor of 10 or more, that part of the current lead is thermally decoupled from the rest of the lead.