Experimental apparatus for measuring the characteristics of HTS coils under controllable magnetic field, orientation and temperature
The electric field vs. current density (E-J) characteristics of high temperature superconducting (HTS) tapes strongly depend on the magnetic field, its orientation and operation temperature. In order to investigate the current distribution and electromagnetic phenomena in HTS tapes, we have developed an experimental apparatus which can measure the characteristics of HTS tapes under various conditions of magnetic field (0-5 T), its orientation and temperature (10-150 K). The magnetic field is generated by cryocooler-cooled superconducting split coils. The field strength as well as its orientation can be freely varied in the sample space (diameter 150 mm, height 30 mm) by controlling the current and its direction of each coil. By applying HTS current-leads with Au-doped Ag-sheathed Bi-2223 tapes for the split coils (100 A) as well as for the sample coil (500 A), the heat in-leak is sufficiently reduced, and hence a flexible experiment without using liquid helium is enabled.