Magnetic Image Effect in Superconducting Magnet and Magnetization Measurement

The magnetic image effect (flux distortion due to the Meissner effect) in superconducting magnets (SCM´s) was studied both theoretically and experimentally. Changes with temperature in the magnetic moment of a current loop coil (as measured by a VSM) were observed; sudden drops at 15 K and 7 K corresponded to the superconducting temperatures of Nb3Sn and NbTi used in the SCM. Experimental results for both image effects and residual magnetic fields agreed with calculations by the finite element method. The image effect tends to cause overestimation of susceptibility and underestimation of the magnetization.