Transport Characteristics and Modelling of ST40 Hot Ion Plasmas

Fuente: arXiv
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Auteurs principaux: Tzanis, MS Anastopoulos, Hardman, MR, Zhang, Y, Zhang, X, Sladkomedova, A, Dnestrovskii, A, Na, YS, Lee, JH, Park, SJ, Gorman, TO, Lowe, H, Romanelli, M, Sertoli, M, Gemmel, M, Woods, J, Willett, HV, Team, ST40
Format: Preprint
Publié: 2025
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_version_ 1866910818706128896
author Tzanis, MS Anastopoulos
Hardman, MR
Zhang, Y
Zhang, X
Sladkomedova, A
Dnestrovskii, A
Na, YS
Lee, JH
Park, SJ
Gorman, TO
Lowe, H
Romanelli, M
Sertoli, M
Gemmel, M
Woods, J
Willett, HV
Team, ST40
author_facet Tzanis, MS Anastopoulos
Hardman, MR
Zhang, Y
Zhang, X
Sladkomedova, A
Dnestrovskii, A
Na, YS
Lee, JH
Park, SJ
Gorman, TO
Lowe, H
Romanelli, M
Sertoli, M
Gemmel, M
Woods, J
Willett, HV
Team, ST40
contents In this paper, the turbulent transport properties of ST40 hot ion plasmas are examined and fully predictive time evolving modelling of a hot ion plasma pulse was performed. Understanding turbulent transport on spherical tokamaks (STs) is challenging due to their unique geometry characteristics. ST40 hot ion plasmas are typically unstable to ion scale Trapped Electron Modes (TEMs) and Ubiquitous Modes (UMs), driven from the kinetic response of trapped particles and passing ions, and electron scale Electron Temperature Gradient Modes (ETGs) at the edge of the plasma. A comparison between the linear unstable modes of the gyro-kinetic code GS2 and the gyro-fluid code TGLF showed that both models agree to a satisfactory level. However, some discrepancy was observed at the core of the plasma where a large fraction of beams ions exists, and electromagnetic effects are potentially important. Turbulent fluxes were also observed to be somewhat overpredicted with TGLF. The core heat ion transport is observed to be close to neoclassical levels due to turbulence suppression from high rotation and fast ion stabilisation, while the edge region is dominated by anomalous transport in both ions and electrons. As a result, enhanced energy confinement is observed in those plasmas driven by the reduced turbulent core region and the confined beam ions. Fully predictive simulations using the ASTRA transport solver coupled with SPIDER, NUBEAM, NCLASS and TGLF together with a novel reduced scrape of layer (SOL) model for the simulation of the last closed flux surface (LCFS) boundary conditions was attempted. Agreement in global quantities but also kinetic profiles between the predictive and interpretative modelling as well as experimental measurements was observed.
format Preprint
id arxiv_https___arxiv_org_abs_2502_04993
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Transport Characteristics and Modelling of ST40 Hot Ion Plasmas
Tzanis, MS Anastopoulos
Hardman, MR
Zhang, Y
Zhang, X
Sladkomedova, A
Dnestrovskii, A
Na, YS
Lee, JH
Park, SJ
Gorman, TO
Lowe, H
Romanelli, M
Sertoli, M
Gemmel, M
Woods, J
Willett, HV
Team, ST40
Plasma Physics
In this paper, the turbulent transport properties of ST40 hot ion plasmas are examined and fully predictive time evolving modelling of a hot ion plasma pulse was performed. Understanding turbulent transport on spherical tokamaks (STs) is challenging due to their unique geometry characteristics. ST40 hot ion plasmas are typically unstable to ion scale Trapped Electron Modes (TEMs) and Ubiquitous Modes (UMs), driven from the kinetic response of trapped particles and passing ions, and electron scale Electron Temperature Gradient Modes (ETGs) at the edge of the plasma. A comparison between the linear unstable modes of the gyro-kinetic code GS2 and the gyro-fluid code TGLF showed that both models agree to a satisfactory level. However, some discrepancy was observed at the core of the plasma where a large fraction of beams ions exists, and electromagnetic effects are potentially important. Turbulent fluxes were also observed to be somewhat overpredicted with TGLF. The core heat ion transport is observed to be close to neoclassical levels due to turbulence suppression from high rotation and fast ion stabilisation, while the edge region is dominated by anomalous transport in both ions and electrons. As a result, enhanced energy confinement is observed in those plasmas driven by the reduced turbulent core region and the confined beam ions. Fully predictive simulations using the ASTRA transport solver coupled with SPIDER, NUBEAM, NCLASS and TGLF together with a novel reduced scrape of layer (SOL) model for the simulation of the last closed flux surface (LCFS) boundary conditions was attempted. Agreement in global quantities but also kinetic profiles between the predictive and interpretative modelling as well as experimental measurements was observed.
title Transport Characteristics and Modelling of ST40 Hot Ion Plasmas
topic Plasma Physics
url https://arxiv.org/abs/2502.04993