Evaluation of critical current density based on percolation model in carbohydrate doped MgB_2 wires

摘要

The low field region is somewhat different. The critical current density at low field is mostly determined by the pinning force maximum and the obtained F_m listed in Table I is quite reliable. Consistent with the conventional argument concerning the size dependence of the grain boundary pinning, there is a clear enhancement in the pinning at low sintering temperature for both doped and un-doped samples. On the other hand, contrary to the usual discussion on carbon doping in MgB_2, the pinning force did not increase, but decreased. Comprehensive study has reported in our previous work.