n-value and second derivative of the superconductor voltage-current characteristic

The authors studied the n-value (V varies as I/sup n/) and second derivative (d/sup 2/V/dI/sup 2/) of the voltage-current curve of high- and low-temperature superconductors and superconductor simulators. They used these parameters for diagnosing problems with sample heating and data acquisition, and as indicators of the superconducting-to-normal state transition. The superconductor simulator may be useful in testing the measurement system integrity and reducing measurement variability since its characteristics are highly repeatable.<
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