An investigation of the effective parameters causing the critical current drop in a small high temperature superconducting D-shaped coil

In this paper, the dependency of the critical current on the magnetic field, temperature, and different curvature radii for a specific sample of Bi-2223/AgMg composite tape are investigated. By using this superconducting tape, a D-shaped pancake coil is designed and built. The coil critical current degradation at liquid nitrogen temperature with respect to a straight short sample of the same tape is reported, and also the portion of the bending and self-field contribution in the critical current drop is indicated separately. The hysteresis behavior as a function of the current rate during ramp up and ramp down cases on the voltage-current curve at liquid nitrogen temperature is examined. In addition, the quenching propagation speed is measured at two different radii of curvature of the designed magnet.