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Main Authors: Yan, Qinghao, Diamond, P. H.
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2502.20691
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author Yan, Qinghao
Diamond, P. H.
author_facet Yan, Qinghao
Diamond, P. H.
contents In scenarios where a sustained energetic particle source strongly drives toroidal Alfvén eigenmodes (TAE), and phase-space transport is insufficient to saturate TAE, this novel theory of TAE-zonal mode (ZM)-turbulence -- self-regulated by cross-scale interactions (including collisionless ZF damping) -- merits consideration. Zonal modes are driven by Reynolds and Maxwell stresses, without the onset of modulational instability. TAE evolution in the presence of ZMs conserves energy and closes the system feedback loop. The saturated zonal shears can be sufficient to suppress ambient drift-ITG turbulence, achieving an enhanced core confinement regime. The necessary mechanism is identified. The saturated state is regulated by linear and turbulent zonal flow drag. This regulation leads to bursty TAE spectral oscillations, which overshoot while approaching saturation. Heating by both collisional and collisionless ZM damping deposits alpha particle energy into the thermal plasma, achieving effective alpha channeling. This theory offers a mechanism for EP-induced transport barrier formation, and predicts a novel thermal ion heating mechanism.
format Preprint
id arxiv_https___arxiv_org_abs_2502_20691
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle AE-driven Zonal Modes Produce Transport Barriers and Heat Thermal Ions by Cross-Scale Interactions
Yan, Qinghao
Diamond, P. H.
Plasma Physics
In scenarios where a sustained energetic particle source strongly drives toroidal Alfvén eigenmodes (TAE), and phase-space transport is insufficient to saturate TAE, this novel theory of TAE-zonal mode (ZM)-turbulence -- self-regulated by cross-scale interactions (including collisionless ZF damping) -- merits consideration. Zonal modes are driven by Reynolds and Maxwell stresses, without the onset of modulational instability. TAE evolution in the presence of ZMs conserves energy and closes the system feedback loop. The saturated zonal shears can be sufficient to suppress ambient drift-ITG turbulence, achieving an enhanced core confinement regime. The necessary mechanism is identified. The saturated state is regulated by linear and turbulent zonal flow drag. This regulation leads to bursty TAE spectral oscillations, which overshoot while approaching saturation. Heating by both collisional and collisionless ZM damping deposits alpha particle energy into the thermal plasma, achieving effective alpha channeling. This theory offers a mechanism for EP-induced transport barrier formation, and predicts a novel thermal ion heating mechanism.
title AE-driven Zonal Modes Produce Transport Barriers and Heat Thermal Ions by Cross-Scale Interactions
topic Plasma Physics
url https://arxiv.org/abs/2502.20691