Stress and Strain Measurements on a 5 T Superconducting Magnet During Coil Excitation

A 5 T superconducting magnet with a warm bore has been successfully fabricated and tested at the Institute of Modern Physics of Chinese Academy of Science (IMPCAS). The strains of the superconducting magnet under cryogenic temperature and intense magnetic field were measured by using low-temperature resistance strain gauges where the compensation methods were introduced for eliminating noise effects of both temperature and magnetic field on the strain measurement. A slow ramp rate of the magnetic field was applied during coil excitation of the superconducting magnet to avoid the temperature risen by eddy current. A wireless strain acquisition system was used for the hoop and axial strain measurements of the magnet. It is clarified that the strains measured in the superconducting magnet give much valuable information characterizing the deformation and the stress state at cryogenic temperature and intense magnetic fields. For the purpose of comparison, the steady-state strains and central magnetic field of the superconducting magnet was valuated by means of a coupled FEM. The simulation predictions and the experimental data show good agreements.