Coherent Effects and Impedance (CEI)


The Coherent Effects and Impedances (CEI) section oversees the study of beam coherent collective effects and stability, and provides expertise in the field of beam coupling impedance computation, optimization and specification. Specifically, the section is responsible for:

  • Theoretical and numerical modelling of high-intensity, high-brightness beams, and experimental applications;
  • Development and maintenance of software tools to study coherent multi-particle beam dynamics (e.g. macro-particle, Vlasov);
  • Studies of the coherent effects limiting the performance of the CERN accelerators (due to e.g. beam coupling impedance, space charge, beam-beam, electron cloud, ions) and of their mitigation, in the current frameworks of operation and upgrade (LIU and HL-LHC);
  • Studies of the coherent effects relevant for future synchrotrons and colliders, as defined by the ESPP (PBC, FCC, CLIC, Muon collider, etc.);
  • Development and maintenance of the beam coupling impedance models of present and future CERN accelerators;
  • Beam-induced heating computations, measurements and follow-up;
  • Contribution to machine coordination and beam physics support for the recommissioning of the CERN synchrotrons, their performance ramp up and operation.

The section members actively cover a number of coordination or management roles in

  • Beam physics support for commissioning and operation (e.g., parameter definition, strategy, measurement procedures) of all CERN hadron synchrotron through machine supervision 
  • Machine development studies of the LHC injectors complex
  • LHC Injectors Upgrade (LIU) project and Injectors Performance Panel
  • HL-LHC Work Package 2 - Beam Dynamics (WP2)
  • Interdepartmental impedance activities (Impedance Working Group) and databasing of impedance models of the CERN machines
  • Electron cloud studies across groups and departments (Electron Cloud Working Group)
  • Computing activities within the ABP group and link to IT for the BE department (ABP Computing Panel)