Abstract
The High-Luminosity upgrade of the Large Hadron Collider (HL-LHC) will increase the accelerator’s luminosity by a factor 10 beyond its original design value, giving rise to more collisions and generating an intense flow of debris. A new beam screen has been designed for the inner triplets that incorporates tungsten alloy blocks to shield the superconducting magnets and the 1.9 K superfluid helium bath from incoming radiation. These screens will operate between 60 K and 80 K and are designed to sustain a nominal head load of 15 Wm−1, over 10 times the nominal heat load for the original LHC design. Their overall new and more complex design requires them and their constituent parts to be characterised from a thermal performance standpoint. In this paper we describe the experimental parametric study carried out on two principal thermal components: a representative sample of the beam screen with a tungsten-based alloy block and thermal link and the supporting structure composed of an assembly of ceramic spheres and titanium springs. Results from both studies are shown and discussed regarding their impact on the baseline considerations for the thermal design of the beam screens.
Highlights
In the framework of the High-Luminosity upgrade of the LHC, new screens have been designed for the inner triplets Qx and for D1 [1]
Results are divided into the evaluation of the beam screen thermal pathways and into the thermal conductance measurements of the supporting structure in contact with the cold bore
The most relevant results are the ones obtained for the nominal heat load of 15 W m−1 on the beam screen inner surface and on the tungsten block
Summary
In the framework of the High-Luminosity upgrade of the LHC, new screens have been designed for the inner triplets Qx and for D1 (quadrupoles and dipole in the insertion regions) [1]. They are directly brazed to the tungsten block on one side and to a pad on the other, which in turn is welded to the cooling tube This pad is made out of stainless steel with an 80 μm copper layer, and its purpose is to ensure a weldable surface to the cooling tube while providing a better distribution of the incoming heat load onto its surface. ZrO2 combines excellent mechanical properties with a low thermal conductivity [5] These spheres are the only point of contact between the beam screen and the cold bore (32 per section, 6 mm for Q1 and 4 mm for D1 and the other triplets). The second part focused on assessing the thermal conductance of the supporting spring components in order to estimate the heat load reaching the 1.9 K cold bore
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