Electron cloud studies for the LHC TDI and HL-LHC TDIS

The LHC injection beam stopper (TDI) is designed to protect the machine in case of injection kicker malfunctioning. During the operation it was observed that electron cloud can build up inside the TDI chamber especially for certain openings of movable jaws. Numerical studies were done to estimate the electron flux on the internal surfaces of the device for the present TDI and the future TDIS beam stoppers foreseen for the HL-LHC. Different configurations of the devices as well as possible coating options to reduce electron multipacting are discussed in this report. The results presented here will be used by the vacuum team to quantify the detrimental effect of the electron cloud on the vacuum pressure.