抄録
We have proposed the new method for measuring transport critical current density Jct of high-Tc polycrystalline superconductors on the basis of the exponential critical-state model Jct=J0 exp(- Binter/B0), where J0 and B0 are constant, andBinter is intergrain magnetic-flux density. Full-penetration field Hp and remnant-magnetization saturating field H6 are measured directly from the magnetization hysteresis and the remnant-magnetization curve of the sample, respectively. The model parameters J0 and B0 are derived by substituting Hp and Hs into critical-state equations. A critical current density measured by four-probe method is averaged one of local Jct over the sample exposed to self magnetic field generated by applied current, and increases with decreasing the cross-sectional area of the sample, while the intrinsic property of local Jct can be estimated by the method proposed in this work.
