Study on I-V Behavior of YBCO Film on 5 mm × 10 mm LAO Under DC Pulse by Electric Transport Method.

A set of DC pulse devices was built to measure the 5 mm × 10 mm YBCO sheet in order to evaluate the impact of thermal effect on the superconducting I-V curve (77 K, self-field). Firstly, metal organic deposition method was used to prepare YBCO precursor film on a 5 × 10mm2 lanthanum aluminate single crystal. With the aid of a mask plate, a 15-W laser was used to graphically process the YBCO film after pyrolysis and sintering, or before oxygen absorption, so that the silver gel curing and YBCO oxygen absorption processes could be performed simultaneously. In order to realize two modes of continuous loading current and pulse loading current, a set of power supply and test equipment consisting of a Keithley 6500 multimeter, a Keithley 2280 power supply, two simple programmable controllers, a special fixture, and a stepping motor with deceleration device was designed. This equipment is used to test Tc and Ic of graphically processed YBCO film. YBCO film displayed comparable critical current values in both continuous loading current mode and pulse loading current mode at the same current loading rate. After YBCO film enters the stage of loss of superconductivity, the method of pulse loading current shows lower resistivity than that of continuous loading current, and the ratio of the two resistivities increases further with the increasing of current, which may be because the method of pulse loading current provides more sufficient heat dissipation interval for YBCO. [ABSTRACT FROM AUTHOR]