QuickPIC Simulations on Recent PWFA Experiments at FACET

The plasma wake field accelerator (PWFA) is a promising advanced accelerator concept for making a more compact and cheaper future high energy accelerator. We present QuickPIC simulations of three PWFA experiments at FACET, SLAC. The first one demonstrated high efficiency, high gradient acceleration of electrons with low energy spread through the ``two-bunch'' scheme, in which an electron drive bunch excites a wake while and a second trailing bunch surfing the wake gets accelerated. The second one demonstrates high energy gain of positrons with low energy spread through a ``self-load'' scheme, in which a single positron bunch propagating in the plasma drives a wake wave and the rear part of the positron bunch loads and surfs the wake to high energy. The third one is electron acceleration in a plasma hollow channel, in which an electron bunch propagates through a plasma hollow channel that is pre-ionized by a Bessel laser beam.