Qualification of a Material and a Process for Insulating the LHC Magnet Instrumentation Wiring

The tests described in this note follow an initial series made on various types of instrumentation wiring as described in the LHC project notes 46 and 57. [1]-[2] One limit to the insulation tests in liquid helium was caused by the presence of gaseous helium in part of the experimental set-up, which gave rise to breakdowns which could not be ascribed with certainty to the sample being tested but were more likely to be caused by the contiguous sample sections in the gas. A new set of measurements was therefore made with a more appropriate cryogenic test set-up. In addition, in order to make the best possible allowance for the conditions in which these wires are in the LHC magnets, tests were also made on irradiated samples and in gaseous helium; the latter check was necessitated by the choice of the feed-through tube which takes the wires from the cold masses to the normal environment.