Finite element computation of self field ac losses in a HTS coil
Résumé
An important issue in the development of HTS materials concerns the determination of their ac losses. For a short sample of HTS conductor, it is very usual to determine ac losses under self field conditions either by measurement or by finite element (FE) analyses. The intrinsic E(J) law is used in the FE models which generally lead to a good estimate of the losses. It is unfortunately not the case when dealing with HTS coils (solenoid or racetrack configurations) made from a large number of wires. Indeed, it is unrealistic to consider an explicit highly nonlinear FE model with a too fine mesh. Instead, the wound region could be considered as a continuum, this lead to reduce the computation time and to simplify the problem. The model takes into account the Jc(B) as well as the n(B) laws of the superconducting material. Using this method, AC losses under sinusoidal transport current have been calculated for a BISCOO coil at different frequencies. Measurements are also carried out showing a satisfactory agreement compared to the simulations.