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 (HL) upgrade of the Large Hadron Collider (LHC), scheduled for implementation in 2028, aims to significantly increase physics output of the accelerator machine. This upgrade results in stored beam energies of up to 710 MJ, imposing severe demands on the beam dump systems that must safely absorb this energy within 86 us. This work presents the design and thermo-mechanical assessment of a new vessel for the HL-LHC beam dumps capable of withstanding the increased operational loads. The response of the currently operational Run 3 beam dumps is first analysed using a combination of finite element simulations and experimental validation. The study shows that the existing design would not operate safely under HL-LHC conditions due to large oscillating stresses generated by the particle shower and associated energy deposition, which excite the structural vibration modes of the device. Based on these findings, a series of finite element based optimisation studies are performed to identify stress mitigation strategies and develop an improved beam dump design for HL. The proposed design features a titanium Grade 5 vessel, leveraging the alloy’s low stiffness, low coefficient of thermal expansion, low density, and high specific strength to reduce dynamic stresses induced 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 demonstrate that the new design pf the beam dumps for HL maintains structural integrity under HL-LHC beam impact conditions and satisfies high fatigue safety margins. This work provides a validated design solution for the HL-LHC beam dumps and supports the initiation of their production in 2026.
The High-Luminosity (HL) upgrade of the Large Hadron Collider (LHC), scheduled for implementation in 2028, aims to significantly increase physics output of the accelerator machine. This upgrade results in stored beam energies of up to 710 MJ, imposing severe demands on the beam dump systems that must safely absorb this energy within 86 us. This work presents the design and thermo-mechanical assessment of a new vessel for the HL-LHC beam dumps capable of withstanding the increased operational loads. The response of the currently operational Run 3 beam dumps is first analysed using a combination of finite element simulations and experimental validation. The study shows that the existing design would not operate safely under HL-LHC conditions due to large oscillating stresses generated by the particle shower and associated energy deposition, which excite the structural vibration modes of the device. Based on these findings, a series of finite element based optimisation studies are performed to identify stress mitigation strategies and develop an improved beam dump design for HL. The proposed design features a titanium Grade 5 vessel, leveraging the alloy’s low stiffness, low coefficient of thermal expansion, low density, and high specific strength to reduce dynamic stresses induced 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 demonstrate that the new design pf the beam dumps for HL maintains structural integrity under HL-LHC beam impact conditions and satisfies high fatigue safety margins. This work provides a validated design solution for the HL-LHC beam dumps and supports the initiation of their production in 2026.
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