Halo Diagnostics Overview

Beam halo imaging with a digital optical mask

“…Several approaches have been used to measure halo. These include 1) mechanical devices such as a wire scanners and beam scrappers, which are used to detect halo particles electronically or detect them via induced radiation [3,12]; 2) indirect or secondary emission monitors, which are used to measure particles or induced radiation produced when the beam interacts with residual or purposely injected gas [13] in the accelerator; and 3) direct imaging of beam produced optical radiation that is linearly proportional to the beam charge distribution, e.g. phosphor light, transition, synchrotron, edge and undulator radiation.…”

“…These studies have shown that there are many factors which can contribute [12], e.g., intrabeam scattering, collective instabilities, misalignments, magnet errors, noise, and resonances associated with both intrinsic incoherent processes and collective space charge forces. However, despite a wealth of theoretical and simulation studies, the mechanisms controlling the formation of halo and their interactions are not well understood.…”