Ricardo Fonseca

Positron plasma wakefield acceleration in a self-driven hollow channel

In this work we propose a novel positron driven plasma wakefield acceleration configuration in the non linear regime using tightly focused positron drive beams to create a hollow plasma channel with no background plasma ions, where positrons can accelerate to high energy. A simplified model for the background plasma ion motion in this scenario was analyzed. The proposed scheme was explored numerically resorting to multi-dimensional PIC simulations using the numerical code OSIRS.In this work we propose a novel positron driven plasma wakefield acceleration configuration in the non linear regime using tightly focused positron drive beams to create a hollow plasma channel with no background plasma ions, where positrons can accelerate to high energy. A simplified model for the background plasma ion motion in this scenario was analyzed. The proposed scheme was explored numerically resorting to multi-dimensional PIC simulations using the numerical code OSIRS.

3D simulations of pre-ionized and two-stage ionization injected laser wakefield accelerators

In plasma based accelerators (LWFA and PWFA), the methods of injecting high quality electron bunches into the accelerating wakefield is of utmost importance for various applications. To fully understand the numerical effect of simulating the trapping process, numerous numerical convergence tests were performed to ensure the correctness of preionized simulations which confirm the physical picture first proposed in [1]. We Further investigate the use of a two-stage ionization injected LWFA to achieve high quality monoenergetic beams through the use of 3D PIC simulations. The first stage constitutes the Injection Regime, which is 99.5% He and 0.5% N, while the second stage constitutes the Acceleration Regime, which is entirely composed of He. Two of the simulations model the parameters of the LWFA experiments for the LLNL Callisto laser, at laser powers of 90 and 100TW. energies as high as 680MeV were observed in the 90TW simulation, and those as high as 1.44GeV were observed in the 100TW simulation. The aff...

Exploring the future of laser-plasma acceleration with massively parallel simulations in OSIRIS

The next decade promises tremendous developments in laser plasma interaction experiments, as a new generation of more powerful lasers becomes available. As in the past, numerical simulations will play a critical role, not only to determine optimal experimental parameters, but also as a tool to explore new ideas and concepts. The challenge, however, is that accurate one‐to‐one simulations of these new extreme scenarios are very computationally demanding, even by current standards, where very large infrastructures are typically available. We describe the recent developments in the OSIRIS framework that enable, for the first time, the full‐scale simulation of several future laser‐plasma configurations. The computational advances include, among others, efficient algorithms scalable to hundreds of thousands of CPUs, new hardware features (e.g. GPUs and vector units), novel techniques (e.g. optimal Lorentz frames), detailed diagnostics for direct comparison with experimental results (e.g., radiation emission), ...