Upper Limit Estimation of Resistive Heating Made by No-Insulation HTS Magnet Having Defects

Abstract

Seoul National University and Hanmi Techwin Inc. have launched a program for the development of a large bore, low field, and low-cost high temperature superconductor (HTS) magnet for industrial applications. HTS coils exhibit defect-irrelevant behaviors when wound using no-insulation (NI) technique, i.e., wound without turn-to-turn insulation. Incorporation of defect-irrelevant winding (DIW) technique would be favorable to constructions of HTS magnets as it may drive the cost of production down and curtail construction time if used appropriately. An HTS magnet having a center magnetic field of 2 T and cold bore size of 230 mm has been designed, and charging simulation was performed using a turn distributed circuit model. Defect-irrelevant behaviors are examined stochastically, considering random occurrences of defective turns. Using the turn distributed circuit model indicates that the magnitudes of defects have limited effects on resistive heatings in both steady state and transient operations. The upper bounds of excess heat contributed by defective turns are numerically formulated using characteristic resistances and operating currents.