System size scaling of triangularity effects on global temperature gradient-driven gyrokinetic simulations

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Main Authors: Di Giannatale, Giovanni, Bottino, Alberto, Brunner, Stephan, Murugappan, Moahan, Villard, Laurent
Format: Preprint
Published: 2024
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author Di Giannatale, Giovanni
Bottino, Alberto
Brunner, Stephan
Murugappan, Moahan
Villard, Laurent
author_facet Di Giannatale, Giovanni
Bottino, Alberto
Brunner, Stephan
Murugappan, Moahan
Villard, Laurent
contents In this work, we explore the triangularity effects on turbulent transport employing global gyrokinetic simulations performed with the ORB5 code. Numerous experiments on the Tokamak à Configuration Variable (TCV) and, more recently, on the DIII-D machine, have demonstrated superior confinement properties in L-mode of negative triangularity (NT) over positive triangularity (PT) configuration. This presents a particularly attractive scenario, as L-mode operation eliminates or significantly mitigates the presence of hazardous edge-localized modes (ELMs). However, a full theoretical understanding of all these observations remains elusive. Specifically, questions remain about how NT improvements can extend to the core where triangularity is very small, and whether these improvements can scale to larger devices. This paper addresses these two questions. Our analysis is divided into two parts: we first demonstrate that the confinement enhancement in NT configurations arises from the interdependent edge-core dynamics, and then we present the results of a system size scan. Crucially, we find that the relative turbulent transport reduction of NT over PT appears not to be contingent on machine dimensions or fluctuation scales and is moreover robust with respect to variations in plasma profiles. This insight underscores the fundamental nature of the NT confinement advantage and paves the way for its potential application in future fusion devices, regardless of their size.
format Preprint
id arxiv_https___arxiv_org_abs_2402_16216
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle System size scaling of triangularity effects on global temperature gradient-driven gyrokinetic simulations
Di Giannatale, Giovanni
Bottino, Alberto
Brunner, Stephan
Murugappan, Moahan
Villard, Laurent
Plasma Physics
In this work, we explore the triangularity effects on turbulent transport employing global gyrokinetic simulations performed with the ORB5 code. Numerous experiments on the Tokamak à Configuration Variable (TCV) and, more recently, on the DIII-D machine, have demonstrated superior confinement properties in L-mode of negative triangularity (NT) over positive triangularity (PT) configuration. This presents a particularly attractive scenario, as L-mode operation eliminates or significantly mitigates the presence of hazardous edge-localized modes (ELMs). However, a full theoretical understanding of all these observations remains elusive. Specifically, questions remain about how NT improvements can extend to the core where triangularity is very small, and whether these improvements can scale to larger devices. This paper addresses these two questions. Our analysis is divided into two parts: we first demonstrate that the confinement enhancement in NT configurations arises from the interdependent edge-core dynamics, and then we present the results of a system size scan. Crucially, we find that the relative turbulent transport reduction of NT over PT appears not to be contingent on machine dimensions or fluctuation scales and is moreover robust with respect to variations in plasma profiles. This insight underscores the fundamental nature of the NT confinement advantage and paves the way for its potential application in future fusion devices, regardless of their size.
title System size scaling of triangularity effects on global temperature gradient-driven gyrokinetic simulations
topic Plasma Physics
url https://arxiv.org/abs/2402.16216