The energy of ions bombarding the vacuum chamber walls. Round beams

Abstract

The ion induced pressure instability is a phenomenon, which could compromise the performance of positively charged machines. To mitigate this phenomenon, a vacuum system should be properly designed to provide sufficient pumping at correct locations, this includes an accurate gas dynamics modelling of beam vacuum chamber. The gas dynamics model requires a number of input parameters, among whose the energy of the ions bombarding vacuum chamber walls is the most critical one. This paper studies the energy of ions bombarding the vacuum chamber walls as a function of round beam parameters such as beam/bunch sizes, beam population and bunch spacing, as well as the effect of beam chamber aperture.