Improved Method for Determining the n-Value of HTS Bulks

International audienceThe complete penetration magnetic field Bp is the main feature of a superconducting pellet submitted to an axial applied magnetic field. The electric E-J characteristics of HTS bulk is generally described by a power law E(J) = Ec(J/Jc)^n. The influence of the n-value and applied magnetic field rise rate Vb on the Bp of a HTS cylindrical pellet has been presented in a previous paper. The numerical results presented come from numerical resolution of a non linear diffusion problem. With the help of these simulations a linear relationship between Bp, ln Vb and n-value has been deduced. This comparison allows determining the critical current density Jc and the n-value of the power law based on direct measurement of Bp in the gap between two bulk HTS pellets. In this paper, an improvement of this method is presented. The influence of geometric parameters R and L is studied to give generality to the relationship between Bp, Vb and n-value. Previous Bp formula is confirmed by these new simulations. To correctly connect simulation and experimental results, the influence of spacing e between bulks is studied and presented. A relationship between Bp and measured complete penetration magnetic field Bpm is determined