A Thermomechanical and Electromagnetic Approach For The Design Of High-Intensity Accelerator Components

At the European Council for Nuclear Research (CERN) two projects call for an upgrade of the laboratory particle accelerators to find new physics results: the High-Luminosity Large Hadron Collider (HL-LHC) and the LHC Injection Upgrade (LIU). In this context, beam characteristics such as intensity and stored energy will be doubled. Some of the current accelerator components cannot safely perform their main tasks with these new conditions. As an example, it was demonstrated that the majority of the devices responsible for partially or totally absorbing the beam, the so-called beam intercepting devices (BIDs), have to be redesigned to face the new challenging scenario. These devices, because of their specific functional requirements, usually, have strong electromagnetic interaction with the beam, i.e. high impedance. They are among the strongest impedance sources in the CERN accelerators. Devices with high impedance could generate beam instabilities or they could be overheated because of RF-heating. Thus, at CERN, an impedance minimization campaign for the new BIDs was started, and this thesis reports the results of the campaign. In particular, the manuscript analyzes the impedance of LIU and HL-LHC devices via simulations and measurements. It defines a series of guidelines for minimizing the device impedance and shows examples of the successful application of these guidelines. Furthermore, the impedance induced heating thermo-mechanical effects are also discussed, a new method to simulate them is developed and successfully benchmarked against experimental data. Finally, the manuscript tackles the problem of determining the wakefield and the impedance induced heating of two counterrotating beams passing in the same vacuum chamber. On this topic, some extensions to the present theory are reported.