The Development Programme of Cathodes and Electron Guns for the Hollow Electron Lenses of the High Luminosity LHC Project

Electron lenses: historical overview and outlook

“…Following recommendations of the 2017 review [80], work on the LHC hollow electron beam for active control of the HL-LHC beam halo removal proceeds along several lines: besides the overall design of the 3 m long system (𝐽 𝑒 = 3 A, 𝑈 𝑒 = 10 kV, solenoid fields 4-6 T, 1/2 mm minimum/maximum electron beam radius), several components get developed, constructed and tested at the CERN and Fermilab test stands [81,82]. Comprehensive simulations on the effects of the electron lens -see figure 11 -on the HL-LHC halo population depletion have been carried out, and different operational modes and interplay with the non-linearities introduced by the collider octupoles and chromaticity have been explored [83].…”

Beam physics research with the IOTA electron lens

“…In the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory, electron lenses allowed experiments to reach significantly higher luminosities [23]. Recently, hollow electron lenses for active halo control were included among the upgrades of the Large Hadron Collider at CERN to reach higher luminosities (HL-LHC Project) [24][25][26][27][28][29][30]. Future applications also include space-charge compensation in synchrotrons at FAIR [31].…”

“…In collaboration with CERN [26,105], they are being considered in cases where larger current densities or lower operating temperatures are required. Although we have not been able to pursue it so far, another development that would significantly simplify the design of compact electron lenses are axially symmetric sources and collectors mounted around the main beam pipe, eliminating the need for the toroidal sections [106][107][108].…”