Beam dynamics in resonant plasma wakefield acceleration at SPARC_LAB

Strategies to mitigate the increase of witness emittance and energy spread in beam driven plasma wakefield acceleration are investigated. Starting from the proposed resonant wakefield acceleration scheme in quasi-non-linear regime that is going to be carried out at SPARC_LAB, we performed systematic scans of the parameters to be used for drivers. The analysis will show that one of the main requirements to preserve witness quality during the acceleration is to have accelerating and focusing fields that are very stable during all the accelerating length. The difference between the dynamics of the leading bunch and the trailing bunch is pointed out. The classical condition on bunch length k(p)sigma(z) = root 2 seems to be an ideal condition for the first driver within long accelerating lengths. The other drivers show to follow different longitudinal matching conditions. In the end a new method for the investigation of the matching for the first driver is introduced.