2026/02/05 by Greg A. Riggs, Mark E Koepke, William W Heidbrink +2 · 1 voice
Physics and Astronomy · #Magnetic confinement fusion research #Nuclear physics research studies #Laser-Plasma Interactions and Diagnostics
paper · doi:10.1088/1741-4326/ae424a
openalex publication_date 2026/02/05 · openalex created_date 2026/02/07 · openalex updated_date 2026/06/11
Abstract In magnetic confinement fusion, toroidicity-induced Alfvén eigenmodes (TAEs) are well-studied, weakly stable solutions of the linearized ideal magnetohydrodynamic equations. Driven unstable by suprathermal populations of energetic particles, TAE pose a key vulnerability to the confinement of high-energy alpha particles generated by fusion reactions. Hence, it is paramount to understand TAE dynamics if a working reactor is to be realized. In this work, we detect and characterize signatures of nonstationary nonlinear coupling between TAE using a novel, time-resolved bispectral analysis; results are supported by analytic signal of band-passed data. Crucially, a stationary phase relationship between two TAE and a nascent low frequency fluctuation is observed precisely when the triple product of magnetic fluctuation amplitudes is enhanced. Local mode number and frequency spectrum, gleaned from beam-emission spectroscopy, corroborates simultaneous satisfaction of nonlinear matching conditions, and provides a tool to identify theorized pathways of energy transfer, e.g. TAE parametric instability.