Abstract Details
| status: | file name: | submitted: | by: |
|---|---|---|---|
| approved | sherwood2026_abstract_namili_v2-1.pdf | 2026-02-27 16:48:19 | Nami Li |
| approved | sherwood2026_abstract_namili_v2.pdf | 2026-02-27 16:44:39 | Nami Li |
Abstracts
Author: Nami Li
Requested Type: Consider for Invited
Submitted: 2026-02-27 16:34:21
Co-authors: X.Q. Xu, B. Dudson, R. Falgout
Contact Info:
LLNL
7000 EAST Ave.
Livermore, CA 94550
USA
Abstract Text:
Edge-localized modes (ELMs) eject intense bursts of heat and particles that threaten plasma-facing components in future fusion reactors and remain a critical challenge for devices such as ITER. While external actuators—including resonant magnetic perturbations (RMPs) and pellet pacing—can mitigate ELMs in present experiments, a passive, self-regulating mechanism would be transformative for reactor-scale operation.
Building on nonlinear BOUT++ simulations that established ELM crash dynamics (Phys. Rev. Lett. 105, 175005, 2010), extended them to a tearing-parity n=1 trigger with two-stage relaxation (Phys. Plasmas 31, 032513, 2024), and identified a plasmoid-mediated reconnection pathway at high Lundquist number S (Nucl. Fusion 63, 126042, 2023), we demonstrate that turbulence-driven zonal magnetic fields (ZMFs) provide a key nonlinear feedback that suppresses avalanche-like propagation. Full-torus simulations show that turbulence-driven zonal flows (ZFs) mitigate the initial crash through shear, but alone allow avalanche-like propagation to persist, sustained by a large inward flow driven by a net perturbed radial force. In contrast, self-generated ZMFs provide a compensating Lorentz-force feedback that suppresses the axisymmetric (n=0) perturbed radial force imbalance between magnetic stresses and pressure gradients (J×B≈∇P), converting avalanches into localized turbulence.
Although the early crash dynamics depend on the specific linear instability drive, including resistive-ballooning and ideal peeling–ballooning cases, AMF–mediated suppression of the perturbed force imbalance emerges as a universal nonlinear regulatory mechanism in the post-crash phase. The predicted signatures—radial electric-field shear and parallel current redistribution—are accessible to existing diagnostics, enabling experimental assessment in present devices and ITER-relevant regimes.
Characterization: 2.0
Comments:
This research was conducted on behalf of the US DOE at Lawrence Livermore National Laboratory (LLNL) under Contract DE-AC52-07NA27344 and was supported by the SciDAC ABOUND Project, SCW1832.