Application of FAR3d gyro-Landau fluid model for analyzing AE instability in stellarators

Stellarators are promising fusion devices that aim to achieve controlled nuclear fusion by confining plasma using complex magnetic field configurations. However, the presence of energetic particles (EPs) within the plasma can give rise to instabilities such as Alfvén eigenmodes (AEs) that can degrade plasma confinement. Simulation codes can be extremely useful in understanding the nature of these instabilities and mitigating them. Both global and flux-tube gyrokinetic simulations have been employed for studying plasma instabilities and turbulence in different stellarator devices. These studies highlight the importance of choosing the range of computational domain for the convergence of frequency and growth rate calculations for these modes. In present study, we aim to apply a global gyrofluid code FAR3d to analyze EP driven instabilities in stellarators. Our goal is to identify how the computational domain such as radial resolution, number of toroidal families in simulation, etc., impact the convergence of frequency and growth rate calculations of the AEs, specifically when helical couplings are included. The role of plasma profiles and parameters on AE instability in stellarators shall also be studied.