Abstract Details
Abstracts
Author: Nikolai N Gorelenkov
Requested Type: Poster
Submitted: 2025-03-13 12:40:36
Co-authors: V.N. DUARTE, M.V. GORELENKOVA
Contact Info:
PPPL, Princeton University
PO451
Princeton, NJ 08543
USA
Abstract Text:
We address a critical challenge for future burning plasmas: ensuring that high-energy fusion products—alpha particles and auxiliary heating beam ions—remain confined long enough to offset thermal plasma energy losses. This confinement can be disrupted by one of the most detrimental collective phenomena: the instability of low-frequency Alfvén eigenmodes (AEs), such as toroidicity-induced AEs and reversed shear Alfvén eigenmodes.
To assess the potential impact of unstable AEs on fast-ion relaxation in ITER steady-state scenario we analyze recently developed resonance-broadened quasi-linear (RBQ) code (N. N. Gorelenkov & V. N. Duarte, PLA'21), which builds upon a revised quasi-linear theory (V. N. Duarte et al., PRL'23). Our findings indicate that AE instabilities can affect both neutral beam ions and alpha particles, though fast-ion transport is expected to remain minimal in that case under the assumptions of classical particle slowing down. However, quasi-linear theory suggests that AE amplitudes could be amplified by background microturbulence—an aspect beyond the scope of this study due to the significant computational effort required for evaluation.
Our investigation studies energetic particle (EP) relaxation dynamics through multiple approaches: a detailed linear stability analysis of the sub-cyclotron Alfvénic spectrum using ideal MHD simulations with NOVA, drift-kinetic calculations with NOVA-C to assess wave-particle interactions and AE growth/damping rates, and predictive quasi-linear modeling combined with the global particle code NUBEAM to evaluate EP relaxation on the equilibrium time scale. The last step includes the renormalization of AE driven diffusion for evolving EP pressure by a fast ion pressure factor using the current state of EP confinement. One potential concern for ITER plasma operations is the effect of Alfvénic modes on current drive, which could hinder the realization of a self-sustained steady-state plasma scenario.
Characterization: 5.0
Comments: