Simulations of Electron-Proton Beam Interaction before Plasma in the AWAKE Experiment

The on-axis injection of electron bunches in the proton-driven plasma wake at the AWAKE experiment at CERN implies co-propagation of a low-energy electron beam with the long high-energy proton beam in a common beam pipe over several meters upstream of the plasma chamber. The possible effects of the proton-induced wakefields on the electron bunch phase space in the common beam pipe region may have crucial implications for subsequent electron trapping and acceleration in plasma. We present the CST Studio simulations of the tentative common beam pipe setup and the two beam co-propagating in it. Simulated effects of the proton wakefields on electrons are analysed and compared to analytical predictions.