In this work we propose a scheme for high quality beam driven plasma wakefield acceleration that exploits a combination of the wakefield generated by a low density driving bunch and an high beam loading effect of the trailing bunch. The trailing bunch is injected in a region where the focusing field generated by the driving bunch is negligible and the focusing effect derives mostly from the transverse self generated wake.
The linear cold plasma fluid equations are used to derive the transverse matching conditions for the driving bunch. We develop the trailing bunch transverse matching conditions using a variant of the ion column model. The energy spread growth is derived and minimized analytically. A realistic working point to be exploited at SPARC_LAB is designed and numerically tested using simulation codes.