Impulse measurement of dynamic current-voltage curves of superconducting tape at various lengths and shapes of current waves

Abstract

Impulse measurement enables fast measuring at high instantaneous currents and low power loading condition. Many applications of superconductivity utilize high currents. Research of superconductivity at high continuous currents is complicated due to considerable heat load into cooled space and big dimensions of measurement apparatus. These problems can be eliminated using of impulse methods. In presented impulse measurements current impulses are supplied into the HTSC Ag/BiSCCO multifilamentary composite tape. The presented experimental results were obtained using the impulse source of unipolar current waves in millisecond and submillisecond domain with instantaneous currents up to 5 kA. The shape of almost-periodic current wave is defined by multiplication function of damped exponential and half-sinusoidal time behaviour. The impulse shaping circuit of source enables to obtain aperiodic behaviour with wide variety of generated impulse duration too. These aperiodic current waves were also used for experiment. The dynamic current-voltage curves were measured using four-point method for various lengths and shapes at comparable magnitudes of current waves. The components of voltage induced by the changing magnetic flux in a measurement loop formed by the potential wires were measured also simultaneously by another contactless loop. These voltages were used for compensation of measured signals.