AN AUTOMATED-SYSTEM FOR CURRENT-VOLTAGE CHARACTERIZATION OF CERAMIC SUPERCONDUCTORS

An automated system for determinations of transport current-voltage. ( I-V) characteristics as a function of temperature (25-125 K), magnetic field (0-1.6 T), and magnetic field orientation (-125 to +145 degrees ) is described. Currents of up to 100 A are applied either as a contin uous ramp or as pulses of 2-100 ms duration. A closed-cycle helium ref rigerator provides a rapid (similar to 45 min), convenient, cost effec tive, cooldown from 300 to 25 K. Control of current, temperature, magn etic field, and field orientation is fully automated and requires no u ser interaction. The characterization of performance of a ceramic supe rconductor typically involves several temperatures, fields, and orient ations and requires 8-30 h to complete. (C) 1996 American Institute of Physics.