Thermal Stability Of A Quasi-isotropic HTS Strand

Over the last few years, significant progress has been made on practical high temperature superconducting (HTS) wire, especially ReBCO wire so called the second generation (2G) HTS wire, its critical current density continually increases and anisotropy is also improved. International Companies have achieved the ability to routinely manufacture kilometer-class high performing 2G HTS wire. Meanwhile, the researches on high-capacity superconductors used ReBCO wire have been made certain progress. Several of high-capacity conductors, such as CORC (Conductor On Round Core), HTS cable, Roebel Cable and TSTC (Twisted Stacked-Tapes Cable), have been put forward for power application.The thesis mainly presents the thermal stability of a quasi-isotropic strands composed of stacked 2G wires, including the calculation of the minimum quench energy (MQE) and the quench propagation velocity (QPV). The strand is fabricated by mature welding metal sheath which encases on four sub-strand made from 2G wires. The sheaths may be made from different kinds of metals such as copper, aluminum and stainless-steel. The thermal stability of the 2G HTS wire is simulated by Comsol 5.0 firstly and it is proved that the ability of the wire to resist the external heat interference is limited. Then the thermal stability of the strand is calculated and the stability of the strand is stronger than the wire. The strand is put in the external field which results in that the critical current is higher than the operating current and the heat generated in the strand would cause the quench. The simulated results are in agreement with the experimental results. The stability of strands with copper and aluminum sheaths is higher than that one with stainless steel sheath because the stainless steel has much higher resistivity and lower thermal conductivity than the one of copper or aluminum.