Abstract Details
Abstracts
Author: Simone Cavallero
Requested Type: Poster
Submitted: 2026-03-19 12:28:27
Co-authors: F. Porcelli, V. Duarte
Contact Info:
Politecnico di Torino and PPPL
100 Stellarator Road
Princeton, New Jersey 08540
US
Abstract Text:
The physics of axisymmetric (n=0) perturbations in magnetically confined plasmas is typically described within the framework of linear MHD, where different classes of modes have been associated with distinct oscillation mechanisms. In particular, macroscopic instabilities such as Vertical Displacement Oscillatory Modes (VDOMs) and wave-like solutions such as Global Alfvén Eigenmodes (GAEs) are usually treated within separate interpretive frameworks, despite following from closely related equations. Within an analytical and numerical analysis of the linear MHD eigenvalue problem in the n=0 limit, we show that both VDOM-like and GAE-like solutions can be obtained as distinct branches of the same underlying system. These solutions coexist within the same formalism and arise from different eigenstructures and balances between restoring forces, providing a unified interpretation of axisymmetric modes as multiple solutions to a single linear problem. Motivated by this interpretation, we investigate how to formulate a wave–particle description of VDOM-like solutions beyond the linear regime. Extending the analysis to quasilinear and nonlinear dynamics requires expressing the problem in a form suitable for wave–particle interaction theory. Our ongoing work focuses on identifying the resonance structure and phase-space formulation needed to describe the interaction between the mode and particles. In this context, we aim to apply nonlinear wave–particle theory to derive analytical predictions for the saturation and temporal evolution of VDOMs, with possible extensions to GAE-like branches. The main challenge lies in making these theories analytically tractable for n=0 modes, where the definition of coupling coefficients and resonant dynamics is nontrivial. The goal is to construct a framework enabling a first-principles description of the interaction, aiming to identify parametric dependencies for saturation levels to predict and interpret experimental outcomes.
Characterization: 4.0
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