Cargando…

H-mode dithering phase studies on ST40

The dithering H-mode phase, characterized by oscillations, is generally observed at input power values close to the L-H transition power threshold and low plasma collisionalities (low electron density and/or high plasma temperature). Measurements to characterize the dithering phase are presented for...

Descripción completa

Detalles Bibliográficos
Autores principales: Andrew, Yasmin, Bland, James, Buxton, Peter, Dnestrovskij, Alexei, Gryaznevich, Mikhail, Kim, Eun-jin, Romanelli, Michele, Sertoli, Marco, Thomas, Paul, Varje, Jari
Formato: Online Artículo Texto
Lenguaje:English
Publicado: The Royal Society 2023
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9805817/
https://www.ncbi.nlm.nih.gov/pubmed/36587816
http://dx.doi.org/10.1098/rsta.2021.0225
_version_ 1784862411142987776
author Andrew, Yasmin
Bland, James
Buxton, Peter
Dnestrovskij, Alexei
Gryaznevich, Mikhail
Kim, Eun-jin
Romanelli, Michele
Sertoli, Marco
Thomas, Paul
Varje, Jari
author_facet Andrew, Yasmin
Bland, James
Buxton, Peter
Dnestrovskij, Alexei
Gryaznevich, Mikhail
Kim, Eun-jin
Romanelli, Michele
Sertoli, Marco
Thomas, Paul
Varje, Jari
author_sort Andrew, Yasmin
collection PubMed
description The dithering H-mode phase, characterized by oscillations, is generally observed at input power values close to the L-H transition power threshold and low plasma collisionalities (low electron density and/or high plasma temperature). Measurements to characterize the dithering phase are presented for the low aspect ratio, high magnetic field tokamak, ST40. The dithering phase oscillation frequency is observed between 400 and 800 Hz and demonstrates an inverse relationship with core plasma density. Dithering phase H-modes are documented across a nonlinear, low-density power threshold operational space, with signature low- and high-density branches. The minimum power threshold for dithering H-mode access is measured at a core, line average electron density of 4.7(±0.5) × 10(19) m(−3), close to a predicted value of 4.1(±0.4) × 10(19) m(−3) from multi-machine studies. ASTRA calculated values of power coupled to the ion species, at the dithering H-mode transition, exhibit a similar nonlinear dependence on density. This analysis points to the important contribution of the ion thermal channel to the L-H phase transition. The low-frequency plasma density and D-alpha dithers appear to be accompanied by sudden bursts of magnetohydrodynamic (MHD) activity. A simple model is tested to demonstrate a possible scenario of self-regulation among turbulence, zonal flows, pressure (density) gradient and MHD activities. This article is part of a discussion meeting issue 'H-mode transition and pedestal studies in fusion plasmas'.
format Online
Article
Text
id pubmed-9805817
institution National Center for Biotechnology Information
language English
publishDate 2023
publisher The Royal Society
record_format MEDLINE/PubMed
spelling pubmed-98058172023-01-12 H-mode dithering phase studies on ST40 Andrew, Yasmin Bland, James Buxton, Peter Dnestrovskij, Alexei Gryaznevich, Mikhail Kim, Eun-jin Romanelli, Michele Sertoli, Marco Thomas, Paul Varje, Jari Philos Trans A Math Phys Eng Sci Articles The dithering H-mode phase, characterized by oscillations, is generally observed at input power values close to the L-H transition power threshold and low plasma collisionalities (low electron density and/or high plasma temperature). Measurements to characterize the dithering phase are presented for the low aspect ratio, high magnetic field tokamak, ST40. The dithering phase oscillation frequency is observed between 400 and 800 Hz and demonstrates an inverse relationship with core plasma density. Dithering phase H-modes are documented across a nonlinear, low-density power threshold operational space, with signature low- and high-density branches. The minimum power threshold for dithering H-mode access is measured at a core, line average electron density of 4.7(±0.5) × 10(19) m(−3), close to a predicted value of 4.1(±0.4) × 10(19) m(−3) from multi-machine studies. ASTRA calculated values of power coupled to the ion species, at the dithering H-mode transition, exhibit a similar nonlinear dependence on density. This analysis points to the important contribution of the ion thermal channel to the L-H phase transition. The low-frequency plasma density and D-alpha dithers appear to be accompanied by sudden bursts of magnetohydrodynamic (MHD) activity. A simple model is tested to demonstrate a possible scenario of self-regulation among turbulence, zonal flows, pressure (density) gradient and MHD activities. This article is part of a discussion meeting issue 'H-mode transition and pedestal studies in fusion plasmas'. The Royal Society 2023-02-20 2023-01-02 /pmc/articles/PMC9805817/ /pubmed/36587816 http://dx.doi.org/10.1098/rsta.2021.0225 Text en © 2023 The Authors. https://creativecommons.org/licenses/by/4.0/Published by the Royal Society under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/4.0/ (https://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, provided the original author and source are credited.
spellingShingle Articles
Andrew, Yasmin
Bland, James
Buxton, Peter
Dnestrovskij, Alexei
Gryaznevich, Mikhail
Kim, Eun-jin
Romanelli, Michele
Sertoli, Marco
Thomas, Paul
Varje, Jari
H-mode dithering phase studies on ST40
title H-mode dithering phase studies on ST40
title_full H-mode dithering phase studies on ST40
title_fullStr H-mode dithering phase studies on ST40
title_full_unstemmed H-mode dithering phase studies on ST40
title_short H-mode dithering phase studies on ST40
title_sort h-mode dithering phase studies on st40
topic Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9805817/
https://www.ncbi.nlm.nih.gov/pubmed/36587816
http://dx.doi.org/10.1098/rsta.2021.0225
work_keys_str_mv AT andrewyasmin hmodeditheringphasestudiesonst40
AT blandjames hmodeditheringphasestudiesonst40
AT buxtonpeter hmodeditheringphasestudiesonst40
AT dnestrovskijalexei hmodeditheringphasestudiesonst40
AT gryaznevichmikhail hmodeditheringphasestudiesonst40
AT kimeunjin hmodeditheringphasestudiesonst40
AT romanellimichele hmodeditheringphasestudiesonst40
AT sertolimarco hmodeditheringphasestudiesonst40
AT thomaspaul hmodeditheringphasestudiesonst40
AT varjejari hmodeditheringphasestudiesonst40