Theory and simulations of beam dynamics and radiation emission in plasma-based devices

Plasma-based particle acceleration has emerged as a promising alternative to conventional radio-frequency accelerators, offering accelerating gradients in the 10–100 GV/m range and enabling compact and cost-effective accelerator infrastructures. By exploiting plasma wakefields, driven by intense laser pulses or relativistic particle beams, and discharge-generated magnetic fields, plasma-based devices can simultaneously provide accelerating and focusing fields, allowing the generation of high-brightness relativistic electron beams suitable for advanced radiation sources. Within this context, this thesis develops theoretical and numerical tools for the study of beam dynamics and radiation emission in plasma-based devices, with the dual objective of supporting experimental activities and extending the current theoretical framework for plasma-based beam manipulation and radiation production. Three interconnected research directions are addressed. The first concerns the calculation of electromagnetic radiation from relativistic charged particles. A dedicated numerical framework based on Liénard–Wiechert fields was developed for the parallel computation of incoherent and coherent radiation from arbitrary particle trajectories, providing full temporal and spectral resolution. The radiation module, coupled to a fully relativistic tracking code, was developed independently and validated against analytical test cases. It is employed both as a verification tool for the theoretical models presented in this work and as a post-processing framework for particle-in-cell simulation outputs. The second part is devoted to the theoretical study of betatron radiation in plasma channels, with particular emphasis on regimes involving longitudinal particle acceleration and nonlinear transverse oscillations. Extended analytical models are formulated to describe angularly resolved spectra and emission properties, including detailed features of relativistic transverse dynamics and the effects of radiation recoil, while also identifying intrinsic limitations to the achievable spectral purity in systems based on internal particle injection. The third research direction focuses on beam manipulation in curved plasma channels, referred to as Active Plasma Bending devices. A comprehensive theoretical and numerical framework is developed to describe single-particle and beam dynamics, chromatic effects, and radiation emission in these systems, providing practical design equations and highlighting their potential as ultracompact alternatives to conventional magnetic bending elements for beam transport and steering. Overall, the work presented in this thesis contributes to the development of a coherent and flexible modeling framework for next-generation plasma-based accelerators and radiation sources.