Investigation of electron beam emittance and acceleration in interaction of an energetic proton beam with plasma

One of the new approaches in plasma accelerators is to use high-energy proton beam as a driven beam to produce plasma wave. In this approach, the energy of the proton beam is transferred through the formed plasma wave to the witness electron beam for achieving high energies. In this paper, using two-dimensional particle simulation, the interaction of a Gaussian high-energy ion beam with plasma containing linear density with density gradient of 0.03% along the beam propagation direction has been investigated in order to produce a high energy electron beam with a high quality. To investigate the electron acceleration, an 18 MeV witness electron beam is sent to the plasma at the back of the ion beam. The simulation results show that, due to the interaction of the energetic proton beam with plasma, the strong plasma wave field with amplitude 400 MeV/m is created to accelerate the trapped electrons of witness beam to high energy gradients in order of several hundred MeV. Moreover, the evolution of the electron beam emittance as an important parameter in the investigation of the accelerated beam quality, indicates by considering the appropriate parameters for the plasma, proton and electron beams, the emittance of the witness electron beam grows less than 50% compared to its initial value.