Thermomechanical Analysis of Beam Dump Devices for the Large Hadron Collider

The Large Hadron Collider (LHC) is the most powerful accelerator at the European Organisation for Nuclear Research (CERN). It is used to perform fundamental physics research by colliding two counterrotating proton beams after they have been accelerated to nearly the speed of light. The Target Dump Externals (TDE) are responsible for the safe absorption of the LHC particle beams in all possible scenarios, including instances of abnormal machine operation. The LHC undergoes higher levels of stored energy in the particle beams with each operational run, leading to increased thermal loads on the beam dumps. High-Luminosity (HL) LHC is a planned upgrade that increases the stored beam energy by another 26%. Therefore a new set of beam dumps is currently in development. These new objects are foreseen to carry over numerous characteristics of the current design. This emphasises the importance of an improved comprehension of the behaviour of the beam dumps upon beam impact in order to assess their structural performance and improve their design. Thermo-mechanical Finite Element Analyses have previously been performed on the currently operational beam dumps to characterize their behaviour upon beam impact. The beam dumps experience a dynamic response due to the significant thermal loads due to the energy deposited by the particle beams. The almost adiabatic temperature increase in the vessel excites the vibrational modes of the devices due to their sudden thermal expansion. Up until now, however, the model showed limited ability to reproduce the displacements measured by the sensors installed on the devices. Furthermore, it does not include the support frame which can potentially influence the simulated vibrational response. Therefore, the reliability of these models has not yet been fully validated. Therefore, they cannot be used for detailed stress analyses. This thesis describes the development of an improved Finite Element model of the beam dumps that includes their support frames. The aim is to simulate the behaviour of the devices more accurately and to create a base for detailed stress analyses. Its validity is shown by benchmarking the simulation results with available vibrational measurement data for the operational beam dumps. The developed model compares significantly better with measurement data. This forms a validation of the developed model and the methodology of simulation, increasing security in future design and development. Furthermore, this model can be used to perform detailed sub-analysis of the support frame and its cables. This is of significant use for the design and development of the new generation of LHC beam dumps.