Design of the High Luminosity Large Hadron Collider Beam Dump Vessel
Author
Lund, Asbjørn Lassen
Term
4. term
Education
Publication year
2026
Submitted on
2026-03-13
Pages
60
Abstract
The High-Luminosity upgrade of the Large Hadron Collider (HL-LHC), planned for 2028, will increase the machine’s physics output. It also raises the energy stored in the particle beams to up to 710 MJ, which the beam dump system (the device that safely absorbs and stops the beam) must take in just 86 μs. This thesis presents the design and thermo-mechanical assessment of a new vessel for the HL-LHC beam dumps that can withstand these higher loads. We first analyze the currently operational Run 3 beam dumps using a combination of finite element simulations—computer models that divide the structure into many small elements—and experimental validation. The study shows that the existing design would not operate safely under HL-LHC conditions, because the particle shower and associated energy deposition create oscillating stresses that excite the structure’s natural vibration modes. Guided by these findings, we perform finite element–based optimization studies to identify stress-mitigation strategies and develop an improved HL design. The proposed design uses a titanium Grade 5 vessel; the alloy’s low stiffness, low coefficient of thermal expansion, low density, and high specific strength help reduce dynamic stresses during beam impact. The design is validated through thermo-mechanical simulations and detailed fatigue analyses, including assessment of the vessel, the electron beam welded joints, the beam windows, and their bolted flange connection. The results show that the HL design maintains structural integrity under HL-LHC beam impacts and achieves high fatigue safety margins. This work provides a validated design solution for the HL-LHC beam dumps and supports starting production in 2026.
HL-opgraderingen af Large Hadron Collider (HL-LHC), planlagt til 2028, vil øge acceleratorens videnskabelige udbytte. Den øger også den energi, der er lagret i partikelstrålerne, til op til 710 MJ, som beamdump-systemet (en anordning der sikkert absorberer strålen) skal optage på kun 86 μs. Dette arbejde præsenterer design og termomekanisk vurdering af en ny beholder (vessel) til HL-LHCs beamdumps, som kan modstå de forøgede driftsbelastninger. Først analyseres de nuværende Run 3-beamdumps med en kombination af finite element-simuleringer—computerberegninger, der opdeler strukturen i mange små elementer—og eksperimentel validering. Studiet viser, at den eksisterende konstruktion ikke vil være sikker under HL-LHC-forhold, fordi partikelbruseren og den tilhørende energideponering skaber store oscillerende spændinger, som exciterer komponentens naturlige vibrationstilstande. På den baggrund udføres finite element-baserede optimeringsstudier for at finde strategier til at dæmpe spændinger og udvikle et forbedret HL-design. Det foreslåede design anvender en beholder i titanium Grade 5; legeringens lave stivhed, lave termiske udvidelseskoefficient, lave densitet og høje specifikke styrke hjælper med at reducere de dynamiske spændinger under stråleimpact. Designet valideres med termomekaniske simuleringer og detaljerede udmattelsesanalyser, inklusive vurdering af beholderen, de elektronstrålesvejsede samlinger, strålevinduerne og deres boltede flangeforbindelse. Resultaterne viser, at HL-designet bevarer sin strukturelle integritet under HL-LHC-stråleimpact og opfylder høje udmattelsessikkerhedsmarginer. Arbejdet giver en valideret designløsning for HL-LHCs beamdumps og understøtter igangsættelse af produktionen i 2026.
[This apstract has been rewritten with the help of AI based on the project's original abstract]