Temporal resistance variation of the second generation HTS tape during superconducting-to-normal state transition
BackgroundThe quench process in high-temperature superconducting (HTS) wires plays an important role in superconducting power devices, such as fault current limiters, magnets, cables, etc. The superconducting device should survive after the overheating due to quench.MethodsWe studied the evolution of the resistance of the YBCO tape wire during the quench process with 1 ms time resolution for various excitation voltages.FindingsThe resistive normal zone was found to be located in a domain of about 1-4 cm long. The normal state nucleation begins in 40-60 ms after voltage is applied across the HTS tape. In subsequent 200-300 ms other normal state regions appear. The normal domain heating continues in the following 5-10s that results in a factor of 2–3 increase of its resistance.ConclusionsFormation of the normal domain during the quench process follows the same stages for different excitation voltages. Characteristic domain sizes, lifetimes and temperatures are determined for all stages.
Investigation on the Superconducting Properties of YGBCO/STO/YGBCO Trilayer
Superconductor/insulator/superconductor trilayer structure can be used to increase the superconducting properties in self-field of thick REBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-δ</sub> (RE = rare metal) films by inhibiting the thickness effect, as well as improving in-field properties through the interlayer, which acts as a flux pinning interface. The conventional trilayer structure was always prepared symmetrically, namely, the bottom superconducting layer has the same thickness with the top superconducting layer. In this paper, Y<sub>0.5</sub>Gd<sub> 0.5</sub>Ba<sub>2</sub>Cu<sub>3</sub>O<sub>7-δ</sub>/SrTiO<sub>3</sub>/Y<sub>0.5</sub>Gd<sub>0.5</sub>Ba <sub>2</sub>Cu<sub>3</sub>O<sub>7-δ</sub> (YGBCO/STO/Y-GBCO) trilayer films were prepared asymmetrically by pulsed laser deposition on CeO<sub>2</sub> buffered IBAD-MgO tapes, which means the bottom superconducting layer has a different thickness than the top superconducting layer. YGBCO/STO/YGBCO trilayer structure had the same total YGBCO layer thickness of 720 nm and STO interlayer thickness of 80 nm, but a bottom YGBCO superconducting layer of different thickness. Microstructure, surface morphology, and self-field and in-field superconducting properties were systematically investigated. It was found that thicker bottom-layer had almost no internal residual stress, better crystalline quality, and surface morphology, which contributed to better superconducting properties of the YGBCO/STO/YGBCO trilayer sample both under self-field and magnetic field. The phenomenon was explained by the growth model. These results can provide useful information for fabricating trilayer structure with high in-field performance.
Lupin alkaloids from teratogenic and nonteratogenic lupins. II. Identification of the major alkaloids by tandem gas chromatography-mass spectrometry in plants producing crooked calf disease.
The major alkaloids of lupin plants producing crooked calf disease were identified by tandem gas chromatography-mass spectrometry and infrared analysis. The gas chromatography peak invariably present in teratogenic plants proved to be anagyrine. A minor but irregular contaminant of the peak was α-isolupanine. Other alkaloids present but apparently not associated with crooked calf disease were lupanine and two others that were probably epimethoxylupanine and 5,6-dehydrolupanine.