Abstract:
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Electrical multilayer insulations made of Kapton tapes and prepreg or adhesive
Kapton tapes, used in dipole magnets, may offer a complicated arrangement of
thin helium channels which cannot be easily predicted and modelled. Several
insulation systems have been tested in order to characterize their helium
channels pattern. Heat transfer data analysis shows clearly the contribution of
superfluid channels inside the insulation. Appearance of the vortex-free regime
for very small temperature differences (10-5 to 10-3 K) and of the
Gorter-Mellink regime for higher temperature differences allows to establish the
mean value of the channels diameter. We present in this paper the thermal
behaviour of several combinations of insulating materials with different
geometrical arrangements and porosities.
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