Abstract Details
Abstracts
Author: Li Nami
Requested Type: Consider for Invited
Submitted: 2025-02-21 13:24:42
Co-authors: X.Q. Xu, B. Dudson, R. Falgout
Contact Info:
Lawrence Livermore National Laboratory
510 Misty Ln
Livermore, CA 94550
US
Abstract Text:
The intermittent heat loads by edge localized modes (ELMs) in H-mode tokamak plasma should be avoided or mitigated below heat load constraints on plasma facing components, which is a critical challenge for future devices like ITER. Zonal components (n=0 mode) play a significant role in influencing ELM crash dynamics and subsequent energy loss processes. In previous BOUT++, there were limitations in solving the low-n and zonal components due to the flute-ordered approximation in the field solver. To address this, a 3D field solver using HYPRE has been implemented within the BOUT++ framework.
In this work, the 3D field solver for low-n and n=0 modes is verified by linear simulations of the ideal ballooning mode (IBM) and peeling-ballooning mode (PBM) instabilities with shifted circular equilibrium. The difference in growth rates calculated using the 3D field solver versus those calculated with the flute-ordered 1D field solver increases for lower-n modes for IBM. This effect becomes more pronounced in both low-n and high-n modes as the bootstrap current increases for PBM, due to the stronger Laplacian-enhanced parallel derivative effect compared to when flute-ordering is absent.
Nonlinear simulations show that flute-ordering approximation is not critical for high-n ELM dynamics without zonal effects. While n=0 zonal components effects play an important role on high-n ELM crashing and pedestal transport processing. The strong flow shear suppresses the radial transport of pressure filaments, and the ELM size decreases as the zonal flow increases. When the ideal peeling-ballooning modes are stabilized after the initial ELM crash, a new instability is developed due to a strong excitation of zonal vorticity, resulting in a series of secondary crashes. The presence of subsidiary bursts after a main crash increases the effective crash time and energy loss. While with zonal fields effects, the pedestal will get into completely stabilized phase after the secondary crash.
Characterization: 1.0
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.