| Thesis | |
| Report number | CERN-THESIS-2023-382 ; DOI:10.18452/28273 |
| Title | Corrections of high-order nonlinearities in the LHC and High-Luminosity LHC beam optics |
| Author(s) | Dilly, Joschua Werner (CERN) |
| Publication | 2024 - 233. |
| Thesis note | PhD : Humboldt U., Berlin : 2023-09-07 |
| Thesis supervisor(s) | Jankowiak, Andreas ; Tomás, Rogelio |
| Note | Presented 09 Feb 2024 |
| Subject category | Accelerators and Storage Rings |
| Accelerator/Facility, Experiment | CERN HL-LHC CERN LHC |
| Abstract | The impact of high-order nonlinear magnetic field errors on the performance of the Large Hadron Collider (LHC) and its planned High-Luminosity upgrade, the HL-LHC, has been extensively studied. Particularly, the presence of such errors in the Insertion Regions (IR) has shown significant repercussions due to the high beta-functions and feed-down to lower orders caused by crossing schemes. This thesis aims to explore different methods for effectively addressing these high-order errors, with the ultimate goal of identifying and correcting them to optimize beam optics and enhance machine performance. Simulation studies are employed, using a novel and flexible correction algorithm developed during the course of this PhD research. Various strategies are investigated to improve corrections by targeting Resonance Driving Terms (RDTs) associated with diverse error sources. Notably, the algorithm accounts for the feed-down effects and avoids symmetry assumptions between the counter-circulating particle beams. Special attention is devoted to decapole and dodecapole errors, which have demonstrated detrimental effects on amplitude detuning due to feed-down based on previous measurements in the LHC. The anticipated increase in optics sensitivity to errors in the IRs of the HL-LHC further underscores the importance of addressing these errors. The thesis also investigates the influence of misalignments within the IRs housing the detector experiments of both, LHC and HL-LHC, machine configurations, in particular in the final focusing triplets and the nonlinear corrector packages. Correction options are evaluated, focusing on the utilization of the nonlinear corrector packages to address errors in the new separation and recombination dipoles in the HL-LHC, where increased decapole errors had been expected. Experimental studies are conducted to validate the findings. These studies involve replicating the nonlinear errors anticipated in the HL-LHC by powering the correctors in the LHC. Additionally, significant efforts are dedicated to mitigating the feed-down effects arising from decapole and dodecapole field errors in order to minimize amplitude detuning, which plays a crucial role in maintaining optimal beam stability and performance. To address this challenge, novel corrections involving the operational implementation of dodecapole correctors in the IRs have been introduced for the first time. These corrections have demonstrated their efficacy in successfully reducing the undesired feed-down effects. The results of these experiments provide valuable insights into the mitigation of high-order errors and contribute to the overall understanding of beam dynamics in advanced particle accelerators. |
| DOI | 10.18452/28273 |
| Copyright/License | CC BY 4.0 |
Corresponding record in: Inspire
Email contact: [email protected]
Record created 2024-04-16, last modified 2024-11-13
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