Exploration of LWFA Parameter Regimes Using Truncated Azimuthal Modal Geometry in the OSIRIS Simulation Framework

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. Numerous particle-in-cell (PIC) simulations are conducted in order to study various methods of injection and the ideal parameters thereof. 2D slab-geometry simulations are computationally inexpensive, but they are quantitatively, and sometimes even qualitatively inaccurate. One method for reducing the computational load of a 3D simulation is by utilizing a truncated azimuthal mode expansion into the OSIRIS simulation framework [A. Lifschitz et. al 228 (5) (2009)]. Comparison with 3D LWFA simulations shows a great degree of consistency in the characteristics of the self-trapped beam. In addition, higher order cylindrical modes may capture effects such as beam hosing and asymmetric spot size modulation. With this highly efficient 2D-hybrid algorithm it is possible to simulate parameter regimes and scaling laws that are difficult to do in a full 3D Cartesian simulation. Relativistic spot-size self-focusing, which cannot be accurately described in a 2D slab geometry, is also studied.