2026-08-12 –, Room 5
Structured light in interaction with matter has been of interest, particularly as it relates to the production of high intensity gamma beams. In our package, ElectronDynamicsModels.jl, we developed a way to efficiently compute the radiated field resulting from the scattering of a Laguerre-Gauss laser beam off a thin sheet of electrons. The electrons are represented as relativistic classical particles whose motion is integrated using DifferentialEquations.jl. ModellingToolkit.jl was used to formulate the model, allowing us to take advantage of its compiler to generate efficient Julia code. Moreover, this also enables an easy scaling to parallel ensemble simulations on the CPU and GPU. Besides performance, this approach is also useful for enabling higher precision computations, which naturally leverage Julia's multiple dispatch. Once the trajectories are known, the far electromagnetic field can be computed over a grid of pixels from the Lienardt-Wiechert potentials, and finally we compute their Fourier transform.
In our thin sheet model each electron interacts only with the incident radiation and its motion is described by the manifest covariant equations of motion (used here for accuracy and speed reasons) which is a system of 8 ODEs expressed in term of proper time. Thus, by taking advantage of ModellingToolkit.jl's codegen we can readily construct a DifferentialEquations.jl EnsembleProblem in order to perform the embarrassing parallelism of solving for the particles' trajectories.
Since our goal is to compute the Fourier transform of the total radiated field with respect to laboratory time, it's necessary that for each pixel on our screen we accumulate the synchronized (for the sake of coherence) contribution. This is achieved by solving an implicit ODE relating the screen advanced time to the proper time of each particle.
Finally, using the sampled screen electromagnetic field we approximate the continuous Fourier transform using FFTW.jl in order to get the spatial profile and phase of the resulting harmonics of the Thomson scattered radiation, as well as evaluate how coherence is lost for increasingly more intense incident radiation.
- PhD student at the Faculty of Physics of the University of Bucharest.
- Research assistant at the Center of Advanced Laser Technologies (CETAL) of the National Institute for Laser Plasma and Radiation (Romania).
Software Eng. at JuliaHub & PhD student at University of Bucharest.