Numerical modelling of Alfvén waves in fusion plasmas

Alfvén waves are magnetohydrodynamic (MHD) waves that propagate in magnetized plasmas and have been the subject of intense study in laboratory, space and astrophysical plasmas in the last decades. In this study, we will investigate the mechanism of their excitation during Ohmic discharges in magnetically confined fusion plasmas with focus on reversed-field pinch (RFP) and tokamak configurations. The nonlinear 3D MHD cylindrical code SpeCyl will be used to analyze magnetic configurations with increasing level of complexity. Numerical solutions from these simulations will be analyzed by comparing them with the approximate analytical solutions obtained with the linearized ideal MHD model and cold plasma approximation. Alfvénic waves such as shear Alfvén wave (SAW), compressional Alfvén eigenmodes (CAEs) and global Alfvén eigenmode (GAE) will be identified and characterized, alongside phenomena like phase mixing of SAW and resonant absorption of CAEs. Modelling results are in good quantitative agreement with the experimentally observed Alfv´en waves in the RFX-mod device.