Multischaalmodellering van de dynamica van energetische deeltjes en hun radioemissie in coronale en heliosferische plasma’s

Modern society is becoming increasingly dependent on space-based and ground-based technologies that are vulnerable to harsh space weather events. Phenomena such as solar flares and coronal mass ejections (CMEs) are capable to generate solar energetic particles (SEPs) with energies up to several GeV per nucleon for ions and several tens of MeV for electrons, posing serious hazards to astronauts and spacecraft. It is therefore crucial to enhance our understanding of SEP acceleration and transport processes, together with their associated radio signatures, in order to improve forecasting capabilities and take appropriate measures to protect humans and technology. This thesis contributes to these efforts by presenting a novel modelling framework for simulating the acceleration, transport, and radio emission of SEPs in realistic coronal and solar wind environments. The framework was developed in three stages. Starting from an earlier coupled model consisting of the magnetohydrodynamic (MHD) model EUHFORIA and the focused transport code PARADISE, we first improved the modelling of SEP dynamics in the inner heliosphere by replacing EUHFORIA with the more advanced solar wind code Icarus, which supports localised grid refinements and thus higher shock resolutions via adaptive mesh refinement or grid stretching. In the second stage, we extended the domain of study to heliocentric distances below 0.1 au, into the lower corona, by coupling PARADISE to the coronal MHD model COCONUT. In the final stage, we integrated the Ultimate Fast Gyrosynchrotron (GS) Codes into the framework to compute GS and synchrotron from energetic electrons confined in a CME flux rope. Dedicated applications for each stage demonstrate significant advances in modelling particle dynamics in both the corona and the inner heliosphere. The new framework enables realistic simulations of particle acceleration and transport at finely resolved shocks, yielding a more accurate representation of shock effects; the study of confinement and escape of energetic particles in low-coronal magnetic flux ropes, highlighting the role of perpendicular diffusion; and the computation of synthetic type IV radio spectra containing GS emission, offering a valuable diagnostic tool for CME magnetic fields and SEP properties close to the Sun. Moreover, the integration of coronal and heliospheric MHD models represents a crucial step towards global-scale simulations of CME and SEP events from the solar surface to Earth's orbit and beyond, supporting future efforts to disentangle the complex, interconnected processes that govern space plasmas.