Because the proof of principle of operation of plasma-based accelerators is firmly established, much effort is currently been put in demonstrating the generation of relativistic electron bunches with the required quality for various scientific and technological applications. In addition to high-quality beams, several applications also demand very high repetition rates. Here, the long-term plasma dynamics can have a dramatic role in determining beam quality. Understanding the self-consistent interaction between relativistic plasma electrons and the background plasma ions is critical to understand the long-term plasma dynamics, but many open questions still remain.
In this work, we perform particle-in-cell simulations with the code OSIRIS modeling plasma wakefield acceleration experiments done at SLAC-FACET. A beam driver with an energy of 20GeV is used to ionize and drive wakefields in an initially neutral Lithium column. We focus on both the beam dynamics as it passes through the oven and explain and model the ion and electron dynamics for time delays smaller than 200ps, where we show that the Lithium column dynamics is dominated by their initial interaction with the wakefields excited by the driver. We find good agreement between experimental data and simulations at this time scale before impact ionization becomes relevant. We also compare our results with a similar setup where the plasma is pre-ionized, pointing out the main differences and its possible effects on the long-time plasma dynamics.
|Working group||Laser-driven electron acceleration|