  We investigate beam loading and emittance preservation for a high-charge
electron beam being accelerated in quasi-linear plasma wakefields driven by a
short proton beam. The structure of the studied wakefields are similar to those
of a long, modulated proton beam, such as the AWAKE proton driver. We show that
by properly choosing the electron beam parameters and exploiting two well known
effects, beam loading of the wakefield and full blow out of plasma electrons by
the accelerated beam, the electron beam can gain large amounts of energy with a
narrow final energy spread (%-level) and without significant emittance growth.
