Development of a Process to Build Polyimide Insulated Magnets For Operation at 350C
Authors: I.J. Zatz and S. Jurczynski
Abstract:
An extensive R&D program has been conducted that
has confirmed the feasibility of designing and fabricating copper
alloy magnets that can successfully operate at temperatures as
high as 350C. The process, originally developed for the
possibility of manufacturing in-vessel resonant magnetic field
perturbation (RMP) coils for JET, has been optimized for
insulated magnet (and, potentially, other high temperature
component) applications. One of the benefits of high
temperature operation is that active cooling may no longer be
required, greatly simplifying magnet/component design. These
elevated temperatures are beyond the safe operating limits of
conventional OFHC copper and the epoxies that bond and
insulate the turns of typical magnets. This would necessitate the
use an alternative copper alloy conductor such as C18150
(CuCrZr). Coil manufacture with polyimide is very similar to
conventional epoxy bonded coils. Conductors would be dry
wound then impregnated with polyimide of low enough viscosity
to permit saturation, then cured; similar to the vacuum pressure
impregnation process used for conventional epoxy bonded coils.
Representative polyimide insulated coils were mechanically
tested at both room temperature and 350C. Mechanical tests
included turn-to-turn shear bond strength and overall polyimide
adhesion strength, as well as the flexural strength of a 48-turn
polyimide-bonded coil bundle. This paper will detail the results
of the testing program on coil samples. These results demonstrate
mechanical properties as good, or better than epoxy bonded
magnets, even at 350C.
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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-4927 (pdf 275 KB 5 pp)
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