Speaker
Tengming Shen
(Fermilab)
Description
Critical current measurement for Ag/Bi-2212 wires has been typically performed by mounting a short sample (4-10 cm long) heat treated standalone at ~830 °C on a room temperature G-10 sample holder and cooling them down to cryogenic temperatures. During this process samples experience a huge temperature and strain change. This strain effect has not been carefully considered for critical current measurement, despite that critical current of Ag/Bi-2212 wires is well known to depend on strain. At Fermilab and BNL we began to use a new protocol by reacting meter long samples on 96% pure Al2O3 ITER barrels and transferring them to test barrels made from Ti-6Al-4V alloy. We are extending the study to include tests on barrels made from 304 stainless steel, Inconel 600, and G-10. Samples that will be investigated include wires heat-treated using 1 bar partial melt processing and an overpressure partial melt processing. Initial measurements showed that samples tested on the G-10 barrel reproduce Ic for short witness samples, while the Ti-alloy barrel results in a 10% Ic reduction. Fitting these Ic measurement results into the Ic-strain curves from previous research, the thermal pre-strain for the samples measured on the Ti-alloy, Stainless Steel, and G-10 will be evaluated.
*This work is supported by the U.S. Department of Energy, Office of High Energy Physics through a FY12 early career award.*
Author
Liyang Ye
(Fermi National Accelerator Laboratory)
Co-authors
Arup Ghosh
(Brookhaven National Laboratory)
Pei Li
(Fermi National Accelerator Laboratory)
Tengming Shen
(Fermilab)
