The thermal contraction and thermal conductivity of candidate composit
e insulation systems for the International Thermonuclear Experimental
Reactor toroidal field coils were measured from 295 to 4 K. Matrix mat
erials consisted of a diglycidyl ether of bisphenol-A epoxy suitable f
or vacuum impregnation, a tetrafunctional epoxy suitable for pre-impre
gnation, a polyimide system produced by a high-pressure laminating pro
cess, and a bismaleimide system. These matrix materials were combined
with S-2 glass fabric and various barrier systems, such as ceramic and
organic coatings, polyimide film and mica/glass. Thermal contraction
was measured by the strain gauge method in which strain gauges are att
ached directly to the specimen. The thermal contraction in the through
-thickness direction was different at 4 K for each resin system and ch
anged slightly with the addition of electrical barriers. The thermal c
onductivity of the materials, with and without the electrical barriers
, was similar at 4 K, but more distinctive at higher temperatures. The
systems with the ceramic coatings exhibited the highest thermal condu
ctivities at all temperatures.