Beam Induced Effects in Beam Gas Ionisation Monitors Designed for the High-Luminosity LHC Era

Beam induced RF heating has been observed in Beam Gas Ionisation (BGI) monitors of the LHC in the past. These issues will become even more prominent as the beam current is increased by almost a factor of two within the framework of the High-Luminosity (HL) LHC performance upgrade project. For these and other reasons, a redesign of the existing BGIs is therefore carried out by the beam instrumentation group (SY-BI-XEI) to meet future requirements. This report summarises electromagnetic (EM) field simulations of beam induced effects carried out in the RF group (SY-RF-BR) in support of these efforts. Results of beam impedance and coupled thermal simulations, as well as estimates of obtainable shielding of the sensitive Timepix pixel detectors, are presented and discussed. The conclusions drawn from these simulations translate to small changes in the mechanical design of the new BGIs thus significantly reducing the risk of beam induced heating during operation in the future.