Heat Transfer Through the Electrical Insulation of $Nb_{3}Sn$ Cables

For the LHC upgrade projects, CERN will rely on the Nb₃Sn technology to build high field dipole and quadrupole superconducting magnets. In the frame of this R&D program, cooling studies are carried out to determine the heat extraction from this new type of accelerator magnets and the relevant quench limits. In this paper, we present and discuss experimental results of heat transfer through the electrical insulation of Nb₃Sn cables. A cable-stack was prepared using fiberglass sleeves and CTD-101K impregnation resin. Two different measurement methods were compared, consisting of instrumenting the sample before or after the vacuum impregnation. The tests were performed both in 1.9 K superfluid and 4.2 K liquid helium baths, using different heating configurations. We also present results of the numerical model developed to reproduce the experimental results.

I. Introduction

The Large Hadron Collider (LHC) [1] has operated for a few years and produced new physics, while working at about half its nominal beam energy [2]. The full energy will be reached after consolidation of the defective splices of the magnet interconnections, taking place in 2013/2014 [3]. In the meantime, CERN has defined a plan to upgrade the LHC, starting with a Luminosity upgrade, High Luminosity LHC (HL-LHC) from around 2020, possibly followed by an Energy upgrade, High Energy LHC (HE-LHC), around 2030. This plan consists of several projects requiring the development of new superconducting accelerator magnets beyond 10 T [4]: FRESCA2 [5], the 11 T dipole [6], MQXF [7] and a 20 T dipole for HE-LHC [8].