The InPairs project focuses on using self-consistent ab initio massively parallel simulations to study electron-positron pair plasmas under extreme intensities, both in laboratory and astrophysical conditions.
We first focused on acquisition and setup of an hybrid CPU/GPU machine, has the first step for the development and optimization, testing and profiling of the Osiris code at node-level parallelization. This was unique and well beyond the state-of-the-art in particle-in-cell codes and further established OSIRIS as the state-of-the-art particle-in-cell code. We have setup a new Virtual Reality system to explore novel ways for visualizing the resulting simulations with already very exciting results that is already unique.
We have developed a novel radiation diagnostic that has been incorporated into the main simulation tool, Osiris. This simulation tool is new, and is a development that goes clearly beyond the state-of-the-art because it captures the spatiotemporal profile of the radiation, because it can capture the radiation from nearly all the particles in the simulation, and because it runs at run time with the Osiris simulation.
Progress has also been made on exotic laser beams. So far most of the developments regarding the interaction of twisted light with the plasma still did not produce a fundamental difference on the structures produced in the plasma. However, our work was the first to show that the orbital angular momentum of light could be used to access previously unconsidered degrees of freedom on ultra-intense laser-matter interactions in particular on particle acceleration.
The dynamics of ultra relativistic (e-,e+) fireball beam with plasmas has also been explored in detail, by performing two-dimensional particle-in-cell simulations, and for the first time the competition between different plasma instabilities has been identified. We also have shown that the longitudinal energy spread, typical of plasma-based accelerated electron–positron fireball beams, play a minor role in the growth of kinetic plasma instabilities in these scenarios. This has been of paramount importance for a new experiment recently launched at CERN. We worked on a possible novel experimental setups to investigate the generation of Weibel magnetic fields in laser-driven plasmas. The task was complex because the small-scale Weibel fields are usually concealed by the large-scale Biermann magnetic field, which develop as result of the target heating and expansion. Performing ab initio first-principles simulations, we were able to demonstrate that with an opportune tuning of the laser parameters, it is possible to disentangle the two mechanisms and clearly observe the Weibel instability at work. Results of these works have triggered several experiment programs worldwide that now aim to observe these two regimes.
