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Dr.
Eric Gregory, Principal Investigator, ericgregory@charter.net
Mr.
Bruce Zeitlin, Business Official,
DOE
Grant No. DE-FG02-02ER83541
Amount:
$749,821
Although internal tin Nb3Sn superconductors have
been shown to have current densities (Jc) close to the objectives of magnet
designers for future particle accelerators, the AC losses and costs are too
high. This project will combine the
best features of the internal tin and modified jelly roll processes to reduce
these losses and costs. In Phase I,
multiple-barrier restacks were made from single-barrier material and Mono
Element Internal Tin (MEIT) processed material, with and without internal fins.
Each configuration was tested, and comparisons were made among them.
In the material without fins, Jc was maintained, and the
losses were significantly reduced—but not to less than 40µm as desired.
The problem was that in the material containing Ti in the Sn core, strand
breakage was experienced when the subelements were small, and the subelement
material could not be reduced below 0.8mm. Material
without Ti in the core was processed without breakage down to 0.17mm, even
though it had Cu in the Sn. Based on
these results, Phase II will process multiple-barrier subelement billets, both
with and without fins, using NbTa 7.5wt% filaments with no Ti in the cores, and
with thicker barriers and larger filaments than used in Phase I.
A series of restacks, including “double stacked” arrays will be made
and tested to determine the best combination of billet design and restack
procedure. Once this has been
determined with small billets, three larger billets will be made and processed
to yield material that will be supplied to DOE for testing in magnets.
Commercial
Applications and Other Benefits
as described by awardee: Applications
for the technology include open area MRI (MRI is the largest commercial
application of low temperature superconductors), small magnets for high field
laboratory applications and NMR, and fusion and levitated transportation
projects.