Relativistic particle beams are unique tools to explore the frontiers of physics: whether they are used in a particle collider to explore the subatomic world, or to generate X-rays that allow to study the structure and dynamics of atoms and molecules. However, the particle accelerators producing the energetic particle beams can span several kilometers in length. Our vision is that more compact particle sources, based on laser-plasma accelerators, could become a viable complement to the large scale facilities.
By focusing a high-power laser pulse, extreme light intensities are created. Atoms in a gas are rapidly ionised and the main part of the laser pulse interacts with a plasma. The electrons are rapidly pushed out from regions of high intensities while the positively charged ions are immobile on the short time scale of the laser pulse. This leads to a significant space-charge separation and strong electric fields which follow the laser pulse in the form of a plasma wave. A co-propagating electron beam can be accelerated by the plasma wave to high energies in distances that are up to 10,000 times shorter than in conventional accelerators.
At the Lund Laser Centre (LLC), experimental studies of laser-plasma electron acceleration is and has been pursued for several years. This project aims to model the experiments using Particle-in-Cell (PIC) simulations of the laser-plasma interaction. CALDER-CIRC is a relativistic, parallelised, and fully scalable 3D PIC code which is optimised for this problem. As part of a scientific collaboration with the code developers at CEA and LOA/ENSTA (France), simulations will be performed to study several aspects of the physics of laser-plasma accelerators and parametric dependencies supporting the LLC experiments.
This project is a direct continuation of an ongoing project (2017/1-10) and the code CALDER-CIRC is currently running routinely on Aurora at Lunarc. The migration from Alarik to Aurora was very smooth, and with Aurora the efficiency of the code has increased significantly, reducing our demands for core-hours by almost a factor 2. The project is going well, and in addition to ten conference contributions, three journal articles were published, presenting the results from simulations at Lunarc:
H Ekerfelt et al, Scientific Reports 7, 12229 (2017)
M Hansson et al, Plasma Phys Control Fusion 58, 55009 (2016)
M Hansson et al, Phys Rev ST AB 18, 071303 (2015)
We are now planning for more demanding computational studies to solve large problems. We also intend to develop a post-processing tool to model the generation of x-rays in the laser-plasma interactions. To complete this task, we therefore ask for continued access to computational resources for the coming year.