Studies of beam halo became unavoidable feature of high-intensity machines where uncontrolled beam loss should be kept to extremely small level. For a well controlled stable beam such a loss is typically associated with the low density halo surrounding beam core. In order to minimize uncontrolled beam loss or improve performance of an accelerator, it is very important to understand what are the sources of halo formation in a specific machine of interest. The dominant mechanisms are, in fact, different in linear accelerators, circular machines or Energy Recovering Linacs (ERL). In this paper, we summarize basic mechanisms of halo formation in high-intensity beams and discuss their application to various types of accelerators of interest, such as linacs, rings and ERL.

This book documents comprehensive reviews and state-of-the-art studies in the dynamics, diagnostics, and collimation of charged-particle beam halo and in beam-beam interaction. Challenges and solutions to major accelerator facilities in Europe, Asia, and America in the domain of high intensity, high energy, and high brightness charged particles are presented. Latest breakthroughs in physical analysis, engineering design, and experimental tests are included.