2d numerical modelling of magnetism for lu-doped YBCO bulk superconductor using H-formulation

Remanent magnetization in a Y0.5Lu0.5Ba2Ca3Oy sample synthesized by a modified melt powder melt growth (MPMG) method at 25 K has been investigated by both experimental and numerical computation using H-formulation in the finite element method (FEM). Remanent magnetization MREM (T) accurately equals to the difference of the field cooled magnetization MFC(T) and zero field cooled magnetization MZFC (T) in the low field and low temperature range. Numerical computations based on H-formulation can reproduce quite well the experimental data for remanent magnetization as a function of temperature, which provides us an estimation of temperature dependence of the critical current density. The critical current density was estimated as 6,50x108(1-T/Tc)2,5 A/m2 from the best fit curve of MREM (T) for the sample studied. It was shown that the field dependence of the critical current density could be estimated from the comparison of experimantal data and numerical calculations using Jc(H)= Jc0/(1+H/Href) , where Href is a constant characterizing the superconducting sample. Furthermore, both flux density profile and current density profile have been obtained from the numerical calculations for various stages of the field aplications or temperature values during heating process.