Lorentz Force Density Distribution of a Current Carrying Superconducting Tape in a Perpendicular Magnetic Field

The Lorentz force distribution of a high $T_c$ superconducting tape with increasing transport currents in magnetic field ($H_a$) was visualized. The external magnetic field was applied normally to the coated conductor tape surface after zero-field cooling, and the transport current ($I_a$) was increased stepwise from 0 to 90 % of the values of the critical current ($I_c$ ($H_a$)) at applied filed, Ha. The field distribution (H(x)) near the sample surface across the tape width (2w) was measured using the scanning Hall probe method. Applying an inversion to the measured field distribution, we obtained the underlying current distribution (J(x)), from which the magnetic induction, B(x) was calculated with Biot-Savart law. Then Lorentz force per unit length was calculated using F(x)=J(x)${\times}$B(x), which appears to be very inhomogeneous along the tape width due to the complicated distributions of J(x) and B(x).