Quench characteristics of a stabilizer-free 2G HTS conductor

The prospect of medium/high field superconducting magnets using second generation (2G) HTS tapes is approaching reality with continued enhancement in the performance of these conductors. While the cryogenic stability and quench propagation are fundamental issues for the design and safe operation of superconducting magnets, there is insufficient understanding and experimental data for 2G HTS conductors, in particular for the high field scenario at low temperature (<77 K) where the current sharing regime is much larger than in low temperature superconductors. The present work includes a systematic characterization of the relevant thermal-electrical properties used for both qualitative discussion and numerical analysis. Direct measurements of one dimensional adiabatic quench initiation and propagation of a stabilizer-free 2G conductor have been carried out with spatial-temporal recording of temperature and voltage following the deposition of varying local heat pulses to the conductor at different temperatures between 30 K and 77 K carrying different transport currents. The minimum quench energy, and the heat generation in the minimum propagation zone (MPZ) have been obtained as a function of temperature and transport current. The results show quench features unique to HTS such as an increasing MPZ with transport current and higher quench energies at lower temperatures. The experimental results are discussed in the context of current sharing over a large temperature range

The development of high field magnets utilizing Bi-2212 wind & react insert coils

Wind & react Bi-2212 inserts have been manufactured and tested inside a wide-bore NbTi-Nb3Sn magnet providing a background field up to 20T at 4.2K. A pair of six-layer concentric coils both achieved critical currents of 350 A (JE = 200 A/mm2) in a 20T background field. A thicker 14-layer insert made from 119m of round wire had a critical quench current IQ of 287A (JE = 162 A/mm2) at the same field and contributed to a combined central field of 22.5 T. This is a record for a fully superconducting magnet at 4.2 K. The 14-layer coil, equipped with an external protective shunt, was used for an extensive series of quench measurements and endured >150 quenches without damage. Minimum quench energies were found to be in the range of 200-500mJ in background fields of 15-20T when the coil carried 70-95% of its critical quench current

Dataset for "Optimisation of processing conditions during CVD growth of 2D WS2 films from a chloride precursor"

The dataset represents the results of a CVD growth study of monolayer WS2 films on sapphire substrates and underpins the figures in the main manuscript of "Optimisation of processing conditions during CVD growth of 2D WS2 films from a chloride precursor" that has appeared in the Journal of Materials Science. The manuscript describes an annealing protocol that was developed for the Oxford Instruments Nanofab cold wall CVD reactor to optimise the optical properties of the films. The improvement in quality is demonstrated through a systematic analysis of Raman and photoluminescence spectra and line shapes, including 2D maps generated across large area samples. Atomic force microscopy is used to confirm that the films are indeed uniform single monolayers. Finally, a wet transfer process from sapphire to Si/SiO2 substrates is used to demonstrate that the quality of the films remains unaffected