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High Superconductor Fraction, High Engineering Critical Current Density Bi-2212/Ag Wires Fabricated by Ultrasonic Wire Drawing--Global Research and Development, Inc., 110 E. Canal Street, Troy, OH 45373; 937-332-0348
Dr. Florin Buta, Principal Investigator, florin.buta@scientist.com
Mr.
Michael J. Tomsic, Business Official,
DOE Grant No. DE-FG02-04ER83969
Amount: $100,000
Recent work
has shown that Bi:2212/Ag superconducting multifilament wires can be
successfully used to wind Rutherford cables for particle collider magnets, but
the engineering (overall) current density needs to be improved.
Although the critical current density in the superconducting filaments is
quite high, the presence of a large amount of Ag or Ag alloy in the composite
(needed for mechanical strength during the drawing process) limits the
engineering current density. Attempts
to draw composites with higher filling factor (e.g., lower amounts of Ag or Ag
alloy) have either failed or, when drawn with using techniques to reduce the
drawing force, have led to wires with heavily distorted filaments.
This project will develop a new technique for drawing wires with lower
amounts of Ag or Ag alloy, in which ultrasonic vibrations are applied to the
wire drawing die, permitting very large reductions (by a factor as high as
seven) in the drawing force without distortion.
The lower Ag or Ag alloy content increases the superconductor fraction
and hence the engineering current density. In
Phase I, an optimized set of dies will be built for ultrasonic drawing of
Bi:2212/Ag wires. Three billets with
different superconductor fractions will be assembled and drawn, both with
conventional drawing and ultrasonic drawing.
After heat treatment, short samples of wires will be characterized in
terms of filament uniformity, superconducting properties, and mechanical
properties.
Commercial
Applications and Other Benefits as described by the awardee:
Bi:2212/Ag wires with high critical currents in high magnetic fields
should enable particle collider superconducting magnets to generate fields in
excess of 20T, increasing the attainable energy or reducing the size (and
consequently the cost) of future particle colliders. The
technology also could be used to upgrades to existing colliders, such as those
at Fermilab and CERN.