Fermilab, Batavia, USA
CERN, Geneva, Switzerland
EPFL, Lausanne, Switzerland
Collimation with hollow electron beams is a technique for halo removal in high-power hadron beams. The concept was tested experimentally at the Fermilab Tevatron collider using a hollow electron gun installed in one of the Tevatron electron lenses. Within the US LHC Accelerator Research Program and the European HiLumi LHC Design Study, we are investigating the applicability of this technique to the Large Hadron Collider and a conceptual design is being developed. We review some of the main topics related to this study: motivation; halo removal processes; development of hollow electron guns; effects on the proton beam core; and integration in the LHC machine.
Fermilab, Batavia, USA
Pusan National University, Pusan, Republic of Korea
EPFL, Lausanne, Switzerland
Collimation with hollow electron beams is a technique for halo removal in high-power hadron beams. It was experimentally studied at the Fermilab Tevatron collider using electron lenses and it is being considered as an option to complement the collimation system for the LHC upgrades. In the ideal case, the magnetically confined electron beam has a hollow, axially symmetric current-density distribution, whose fields affect the beam halo, leaving the core of the circulating beam unperturbed. We address the effects of imperfections in the current density based upon profiles measured in the Fermilab electron lens test stand. We also study the effect of the bends used to inject and to extract the electron beam from the overlap region. The calculated field distributions will serve as inputs for tracking simulations, which are needed to estimate the effects of the electron lens imperfections on beam core dynamics, such as nonlinearities and emittance growth.