Modelling of shattered pellet injection experiments on the ASDEX Upgrade tokamak

In a shattered pellet injection (SPI) system the penetration and assimilation of the injected material depends on the speed and size distribution of the SPI fragments. ASDEX Upgrade (AUG) was recently equipped with a flexible SPI to study the effect of these parameters on disruption mitigation effic...

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Main Authors: Ansh Patel, A. Matsuyama, G. Papp, M. Lehnen, J. Artola, S. Jachmich, E. Fable, A. Bock, B. Kurzan, M. Hoelzl, W. Tang, M. Dunne, R. Fischer, P. Heinrich, the ASDEX Upgrade Team, the EUROfusion Tokamak Exploitation Team
Format: Article
Language:English
Published: IOP Publishing 2025-01-01
Series:Nuclear Fusion
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Online Access:https://doi.org/10.1088/1741-4326/ade890
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author Ansh Patel
A. Matsuyama
G. Papp
M. Lehnen
J. Artola
S. Jachmich
E. Fable
A. Bock
B. Kurzan
M. Hoelzl
W. Tang
M. Dunne
R. Fischer
P. Heinrich
the ASDEX Upgrade Team
the EUROfusion Tokamak Exploitation Team
author_facet Ansh Patel
A. Matsuyama
G. Papp
M. Lehnen
J. Artola
S. Jachmich
E. Fable
A. Bock
B. Kurzan
M. Hoelzl
W. Tang
M. Dunne
R. Fischer
P. Heinrich
the ASDEX Upgrade Team
the EUROfusion Tokamak Exploitation Team
author_sort Ansh Patel
collection DOAJ
description In a shattered pellet injection (SPI) system the penetration and assimilation of the injected material depends on the speed and size distribution of the SPI fragments. ASDEX Upgrade (AUG) was recently equipped with a flexible SPI to study the effect of these parameters on disruption mitigation efficiency. In this paper we study the impact of different parameters on SPI assimilation with the 1.5D INDEX code. Scans of fragment sizes, speeds and different pellet compositions are carried out for single SPI into AUG H-mode plasmas. We use a semi-empirical global reconnection event (GRE) onset condition to study the material assimilation trends. For mixed deuterium-neon pellets, smaller/faster fragments start to assimilate quicker. However, at the expected onset of the GRE, larger/faster fragments end up assimilating more material. Variations in the injected neon content lead to a large difference in the assimilated neon for neon content below ${\lt}10^{21}$ atoms. For larger injected neon content, a self-regulating mechanism limits the variation in the amount of assimilated neon. We use a back-averaging model to simulate the plasmoid drift during pure deuterium injections with the back-averaging parameter determined by a interpretative simulation of an experimental pure deuterium injection discharge. Again, larger and faster fragments are found to lead to higher assimilation with the material assimilation limited to the plasma edge in general, due to the plasmoid drift. The trends of assimilation for varying fragment sizes, speeds and pellet composition qualitatively agree with the previously reported experimental observations.
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spelling doaj-art-87e9e06e5904423eb4e31fc8830a53f12025-08-20T03:51:35ZengIOP PublishingNuclear Fusion0029-55152025-01-0165808603110.1088/1741-4326/ade890Modelling of shattered pellet injection experiments on the ASDEX Upgrade tokamakAnsh Patel0https://orcid.org/0000-0002-7349-3243A. Matsuyama1https://orcid.org/0000-0002-6634-2025G. Papp2https://orcid.org/0000-0003-0694-5446M. Lehnen3https://orcid.org/0000-0001-6043-8803J. Artola4https://orcid.org/0000-0001-7962-1093S. Jachmich5E. Fable6https://orcid.org/0000-0001-5019-9685A. Bock7B. Kurzan8M. Hoelzl9https://orcid.org/0000-0001-7921-9176W. Tang10https://orcid.org/0000-0002-8406-8349M. Dunne11R. Fischer12P. Heinrich13https://orcid.org/0000-0003-1823-5257the ASDEX Upgrade Teamthe EUROfusion Tokamak Exploitation TeamMax Planck Institute for Plasma Physics , Boltzmannstr. 2, D-85748 Garching, GermanyGraduate School of Energy Science, Kyoto University , Uji, Kyoto 611-0011, JapanMax Planck Institute for Plasma Physics , Boltzmannstr. 2, D-85748 Garching, GermanyITER Organization, Route de Vinon-sur-Verdon , CS 90 046 13067 St. Paul-lez-Durance, FranceITER Organization, Route de Vinon-sur-Verdon , CS 90 046 13067 St. Paul-lez-Durance, FranceITER Organization, Route de Vinon-sur-Verdon , CS 90 046 13067 St. Paul-lez-Durance, FranceMax Planck Institute for Plasma Physics , Boltzmannstr. 2, D-85748 Garching, GermanyMax Planck Institute for Plasma Physics , Boltzmannstr. 2, D-85748 Garching, GermanyMax Planck Institute for Plasma Physics , Boltzmannstr. 2, D-85748 Garching, GermanyMax Planck Institute for Plasma Physics , Boltzmannstr. 2, D-85748 Garching, GermanyMax Planck Institute for Plasma Physics , Boltzmannstr. 2, D-85748 Garching, GermanyMax Planck Institute for Plasma Physics , Boltzmannstr. 2, D-85748 Garching, GermanyMax Planck Institute for Plasma Physics , Boltzmannstr. 2, D-85748 Garching, GermanyMax Planck Institute for Plasma Physics , Boltzmannstr. 2, D-85748 Garching, GermanyIn a shattered pellet injection (SPI) system the penetration and assimilation of the injected material depends on the speed and size distribution of the SPI fragments. ASDEX Upgrade (AUG) was recently equipped with a flexible SPI to study the effect of these parameters on disruption mitigation efficiency. In this paper we study the impact of different parameters on SPI assimilation with the 1.5D INDEX code. Scans of fragment sizes, speeds and different pellet compositions are carried out for single SPI into AUG H-mode plasmas. We use a semi-empirical global reconnection event (GRE) onset condition to study the material assimilation trends. For mixed deuterium-neon pellets, smaller/faster fragments start to assimilate quicker. However, at the expected onset of the GRE, larger/faster fragments end up assimilating more material. Variations in the injected neon content lead to a large difference in the assimilated neon for neon content below ${\lt}10^{21}$ atoms. For larger injected neon content, a self-regulating mechanism limits the variation in the amount of assimilated neon. We use a back-averaging model to simulate the plasmoid drift during pure deuterium injections with the back-averaging parameter determined by a interpretative simulation of an experimental pure deuterium injection discharge. Again, larger and faster fragments are found to lead to higher assimilation with the material assimilation limited to the plasma edge in general, due to the plasmoid drift. The trends of assimilation for varying fragment sizes, speeds and pellet composition qualitatively agree with the previously reported experimental observations.https://doi.org/10.1088/1741-4326/ade890disruption mitigationshattered pellet injectiondisruption modelling
spellingShingle Ansh Patel
A. Matsuyama
G. Papp
M. Lehnen
J. Artola
S. Jachmich
E. Fable
A. Bock
B. Kurzan
M. Hoelzl
W. Tang
M. Dunne
R. Fischer
P. Heinrich
the ASDEX Upgrade Team
the EUROfusion Tokamak Exploitation Team
Modelling of shattered pellet injection experiments on the ASDEX Upgrade tokamak
Nuclear Fusion
disruption mitigation
shattered pellet injection
disruption modelling
title Modelling of shattered pellet injection experiments on the ASDEX Upgrade tokamak
title_full Modelling of shattered pellet injection experiments on the ASDEX Upgrade tokamak
title_fullStr Modelling of shattered pellet injection experiments on the ASDEX Upgrade tokamak
title_full_unstemmed Modelling of shattered pellet injection experiments on the ASDEX Upgrade tokamak
title_short Modelling of shattered pellet injection experiments on the ASDEX Upgrade tokamak
title_sort modelling of shattered pellet injection experiments on the asdex upgrade tokamak
topic disruption mitigation
shattered pellet injection
disruption modelling
url https://doi.org/10.1088/1741-4326/ade890
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