Test and Analysis of Electromagnetic and Mechanical Properties of HTS Coil during Quench State

This paper deals with the analysis of the electromagnetic and mechanical properties of a high-temperature superconducting (HTS) coil, as well as its characteristic as determined through tests using strain gauges. When an operating current is applied to an HTS coil, strain is generated by electromagnetic force. However, additional strain effects in the HTS coil are formed by the Joule heating during quench. Strain was measured with a full-bridge strain gauge mounted directly over the turns. We fabricated an HTS coil wound in a single pancake type to investigate strain characteristics. We also investigated structural analysis by a finite-element method to calculate the strain of the HTS coil. In tests, the strain in the HTS coil was measured during excitation. Test results of the HTS coil have been compared with the theoretical results. Finally, we performed quench propagation tests and could verify the strain effect during quench. The reaction times of the strain gauge at 30 and 80 A are 31.8 and 4.3 s, respectively.