Detection of Current Distribution in Bulk Samples With Artificial Defects From Inversion of Hall Magnetic Maps

A two-sided inverse Biot-Savart algorithm for the computation of critical current distributions in high temperature superconductor (HTS) pellets is introduced. It is based on simultaneous measurement of the magnetic field on top and bottom of the bulk sample with a double Hall probe, and the authors' discretization and QR inversion scheme. It yields current maps which are detailed in the ab-plane for each half of the bulk sample along the c-axis. The computed current is a O(1/z)-weighted average of the real current along the c-axis over each slice. This is the best possible resolution for current maps along the c-axis, regardless of inversion scheme. We demonstrate the new procedure by analyzing a non-c-homo- geneous simulation and a real HTS pellet of cylindrical geometry with asymmetrically drilled holes on both faces.