Equivalent-Circuit Method for Analyzing Shielding Current Density in Axisymmetric HTS Film

An equivalent-circuit method is proposed for calculating the shielding current density especially for the case with an axisymmetric high-temperature superconducting (HTS) film. For this case, the behavior of the shielding current density can be expressed by an electric circuit in which shielding currents flow in multiple HTS loops. By numerically solving the circuit equation together with I-V characteristics for HTS loops, the time variation of the shielding current can be determined. On the basis of the proposed method, the accuracy of the inductive method for measuring the critical current density and the acceleration performance of the superconducting linear acceleration (SLA) system are numerically investigated. The results of computations show that, by using the inductive method, the critical current density can be estimated with an error of 5% or less. Moreover, even for the case with a single electromagnet, the SLA system has a possibility to accelerate a pellet up to over 200 m/s.