Finite Element Analysis of the Temperature Evolution of Bi-2223 Stacked Conductors Under Overcurrent Operation

Abstract

The high-temperature superconductor (HTS) has important application prospects in the field of nuclear fusion. In the high-field large magnets, it is inevitable to be affected by the fault current impact. Under such extreme conditions, superconducting magnet systems will face quench problems and generate large AC loss. AC loss can cause the temperature to rise, which worsens the quench environment. Under the inrush currents, the analysis of the temperature rise pattern of the HTS plays a crucial role regarding the safe operation of the magnet system. In this paper, Comsol’s two-dimensional H method and heat transfer module are used to simulate AC loss and the temperature variation of Bi-2223 HTS conductor for different conditions under the impact of fault current. The temperature can reach up to 81.8 K, 85.2 K, and 90.7 K when the inrush current is 10 kA, 15 kA, and 20 kA, respectively, with a constant flat-topping time of 0.2 s and a ramp-up rate of 100 kA/s. The inrush current is 10 kA, and the flat-top time is 0.2 s, 0.4 s, and 0.6 s, and then, the maximum temperature can reach 81.7 K, 82.5 K, and 83.4 K, respectively. The result shows that as the peak value of the inrush current and the duration of the peak hold time increase, the AC loss and temperature of the HTS conductor increase. As the number of conductor slots increases, the temperature decreases significantly.