17 Nov/23
16:00 - 17:00 (Europe/Zurich)

Diffusive models and chaos indicators for non-linear betatron motion


774/R-013 at CERN


"Understanding the intricate dynamics of beam-halo formation and evolution in circular particle accelerators is paramount for the design and operation of contemporary and future accelerator facilities, especially those employing superconducting magnets, such as the CERN Large Hadron Collider (LHC), its luminosity upgrade HL-LHC, and the prospective Future Circular Hadron Collider (FCC-hh). A recent diffusive framework, based on the Fokker-Planck equation with a diffusion coefficient derived from the Nekhoroshev theorem, has been introduced to model the long-term behavior of beam dynamics and particle losses.

In this seminar, we showcase the theoretical foundation of this framework and introduce a novel measurement protocol for using collimator scans to estimate the Nekhoroshev-like diffusive coefficient based on beam loss data. Despite the absence of the proposed measurement protocol in the existing Run2 LHC collimator scan data, we successfully employ the framework to analyze this data.

Additionally, we explore chaos indicators as a means to investigate the phase-space characteristics of real accelerator lattices through single-particle tracking simulations. We assess the performance of established and newly developed indicators in identifying chaotic behavior in the initial conditions of a modulated Hénon map and subsequently apply this knowledge to the study of realistic accelerator lattices. Our aim is to establish a connection between the presence of chaotic regions in phase space and Nekhoroshev-like diffusive behavior, offering valuable tools to the accelerator physics community.