Novel Use of Water Soluble "Aquapour" As A Temporary Spacer During Coil Winding For The NSTX-U Centerstack
Authors: M. Mardenfeld, J. Chrzanowski, M. Anderson, E. Kearns, C. McFarlane, S. Raftopoulos, W. Reese and R. Tucker
Abstract:
A major facility upgrade to the National
Spherical Torus eXperiment (NSTX-U) is currently underway at
Princeton Plasma Physics Laboratory (PPPL). A key component
of NSTX-U is the fabrication of a new, higher field centerstack
(CS). In order to simultaneously provide robust joints between
the inner and outer legs of the Toroidal Field Coils (TF) and
minimize radial build, the NSTX-U CS design requires that the
Ohmic Heating solenoid (OH) be wound directly on the inner TF
bundle. To protect the OH against thermal expansion stress
during scenarios where the inner TF bundle is hot but the OH is
relatively cool, the completed CS will have a 0.100 inch annular
gap between the outer diameter of the TF bundle and the inner
diameter of the OH solenoid. "Aquapour", a proprietary
material produced by the Advanced Ceramics Manufacturing
Company will be used during manufacture to produce this gap.
After the TF bundle is vacuum pressure impregnated
and cured, a cylindrical "clam shell" mold will be assembled
around it, and a slurry of powdered Aquapour and water will be
pumped into the annular space between the mold and TF bundle.
Subsequent baking will turn the Aquapour solid, and a protective
layer of wet lay-up fiberglass and resin will be added. The OH
solenoid will be wound directly on this wet lay-up shell. After
vacuum pressure impregnation of the OH, the water soluble
Aquapour will be washed away, leaving the required radial
clearance between the TF and OH.
This paper will describe prototyping and testing of this
process, and plans for use on the actual CS fabrication.
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Submitted to: SOFE 2013 Proeedings (June 0213) 25th Symposium on Fusion Engineering, San Francisco, CA (June 10-14, 2013)
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Download PPPL-4924 (pdf 877 KB 4 pp)
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