SOL Transport and Filamentary Dynamics in High Density Tokamak Regimes

Antti Hakola, Nicola Vianello (Corresponding author), Daniel Carralero, Cedric Tsui, Volker Naulin, Matteo Agostini, J Boedo, Benoit Labit, Christian Theiler, Diego Aguiam, Scott Allan, Matthias Bernert, Stefan Costea, Istvan Cziegler, Hugo de Oliveira, Joaquin Galdon-Quiroga, Gustavo Grenfell, Codrina Ionita, Heinz Isliker, Alexander Karpushov & 17 others Jernej Kovacic, Bruce Lipschultz, Roberto Maurizio, Ken McClements, Fulvio Militello, Jeppe Olsen, Jens Juul Rasmussen, Timo Ravensbergen, Holger Reimerdes, Bernd Schneider, Roman Schrittwieser, Monica Spolaore, Kevin Verhaegh, Jose Vicente, Nick Walkden, Wei Zhang, Elisabeth Wolfrum

Research output: Chapter in Book/Report/Conference proceedingConference abstract in proceedingsScientific

Abstract

Addressing the role of scrape off layer filamentary transport is a subject of intense studies in fusion science. Intermittent structures dominate transport in L-Mode and strongly contribute to particle and energy losses in H-mode. The role of convective radial losses has become even more important due to its contribution to the shoulder formation in L-Mode, describing the progressive flattening of the density scrape off layer profile at high density [1]. Investigation of this process revealed the strong relationship between divertor conditions
and the upstream profiles, mediated by filaments dynamics which varies according to the downstream conditions. Preliminary investigations suggested that similar mechanisms occur in H-Mode [1] and that filaments contribute the SOL transport in H-mode density limit (HDL) as well [4]. The present contribution will report on results obtained on ASDEX-Upgrade and TCV tokamaks, to address the role of filamentary transport in high density regimes both in L- and H-Mode. The combined results enlarge the operational space, from a device with a closed divertor, metallic first wall and cryogenic pumping system to a carbon machine with a completely open divertor. The mechanism of shoulder formation
and the role of filaments have been tested against variation of plasma current, magnetic configuration (single and double null plasmas), and divertor neutral densities, through modification of cryopump efficiency. At constant magnetic field the density decay length increases with filament-size independently of the plasma current for both machines in L-mode, consistently with the fact that upstream profiles and divertor neutral pressure exhibit the same trend with normalized Greenwald fraction.
In H-Mode fuelling is insufficient to cause flattening of SOL profiles in the inter-ELM phases since large neutral pressure is needed. Consistently inter-ELM blob size in AUG are found larger whenever the cryopumps is switched off. The resulting picture suggests a complex relationship between divertor and upstream profiles, where filaments are modified by divertor conditions as well as by neutral particles interaction.
Original languageEnglish
Title of host publication27th IAEA Fusion Energy Conference
Subtitle of host publicationProgramme and Abstracts
PublisherInternational Atomic Energy Agency IAEA
Pages396-397
Publication statusPublished - Oct 2018
MoE publication typeNot Eligible
Event27th IAEA Fusion Energy Conference, FEC 2018 - Ghandhinagar, Ahmedabad, India
Duration: 22 Oct 201827 Oct 2018
Conference number: 27
https://www.iaea.org/events/fec-2018

Conference

Conference27th IAEA Fusion Energy Conference, FEC 2018
Abbreviated titleFEC
CountryIndia
CityAhmedabad
Period22/10/1827/10/18
Internet address

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filaments
upstream
profiles
plasma currents
flattening
shoulders
refueling
neutral particles
particle interactions
cryogenics
pumping
energy dissipation
fusion
trends
causes
carbon
decay
configurations
magnetic fields

Cite this

Hakola, A., Vianello, N., Carralero, D., Tsui, C., Naulin, V., Agostini, M., ... Wolfrum, E. (2018). SOL Transport and Filamentary Dynamics in High Density Tokamak Regimes. In 27th IAEA Fusion Energy Conference: Programme and Abstracts (pp. 396-397). International Atomic Energy Agency IAEA.
Hakola, Antti ; Vianello, Nicola ; Carralero, Daniel ; Tsui, Cedric ; Naulin, Volker ; Agostini, Matteo ; Boedo, J ; Labit, Benoit ; Theiler, Christian ; Aguiam, Diego ; Allan, Scott ; Bernert, Matthias ; Costea, Stefan ; Cziegler, Istvan ; de Oliveira, Hugo ; Galdon-Quiroga, Joaquin ; Grenfell, Gustavo ; Ionita, Codrina ; Isliker, Heinz ; Karpushov, Alexander ; Kovacic, Jernej ; Lipschultz, Bruce ; Maurizio, Roberto ; McClements, Ken ; Militello, Fulvio ; Olsen, Jeppe ; Rasmussen, Jens Juul ; Ravensbergen, Timo ; Reimerdes, Holger ; Schneider, Bernd ; Schrittwieser, Roman ; Spolaore, Monica ; Verhaegh, Kevin ; Vicente, Jose ; Walkden, Nick ; Zhang, Wei ; Wolfrum, Elisabeth. / SOL Transport and Filamentary Dynamics in High Density Tokamak Regimes. 27th IAEA Fusion Energy Conference: Programme and Abstracts. International Atomic Energy Agency IAEA, 2018. pp. 396-397
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abstract = "Addressing the role of scrape off layer filamentary transport is a subject of intense studies in fusion science. Intermittent structures dominate transport in L-Mode and strongly contribute to particle and energy losses in H-mode. The role of convective radial losses has become even more important due to its contribution to the shoulder formation in L-Mode, describing the progressive flattening of the density scrape off layer profile at high density [1]. Investigation of this process revealed the strong relationship between divertor conditionsand the upstream profiles, mediated by filaments dynamics which varies according to the downstream conditions. Preliminary investigations suggested that similar mechanisms occur in H-Mode [1] and that filaments contribute the SOL transport in H-mode density limit (HDL) as well [4]. The present contribution will report on results obtained on ASDEX-Upgrade and TCV tokamaks, to address the role of filamentary transport in high density regimes both in L- and H-Mode. The combined results enlarge the operational space, from a device with a closed divertor, metallic first wall and cryogenic pumping system to a carbon machine with a completely open divertor. The mechanism of shoulder formationand the role of filaments have been tested against variation of plasma current, magnetic configuration (single and double null plasmas), and divertor neutral densities, through modification of cryopump efficiency. At constant magnetic field the density decay length increases with filament-size independently of the plasma current for both machines in L-mode, consistently with the fact that upstream profiles and divertor neutral pressure exhibit the same trend with normalized Greenwald fraction.In H-Mode fuelling is insufficient to cause flattening of SOL profiles in the inter-ELM phases since large neutral pressure is needed. Consistently inter-ELM blob size in AUG are found larger whenever the cryopumps is switched off. The resulting picture suggests a complex relationship between divertor and upstream profiles, where filaments are modified by divertor conditions as well as by neutral particles interaction.",
author = "Antti Hakola and Nicola Vianello and Daniel Carralero and Cedric Tsui and Volker Naulin and Matteo Agostini and J Boedo and Benoit Labit and Christian Theiler and Diego Aguiam and Scott Allan and Matthias Bernert and Stefan Costea and Istvan Cziegler and {de Oliveira}, Hugo and Joaquin Galdon-Quiroga and Gustavo Grenfell and Codrina Ionita and Heinz Isliker and Alexander Karpushov and Jernej Kovacic and Bruce Lipschultz and Roberto Maurizio and Ken McClements and Fulvio Militello and Jeppe Olsen and Rasmussen, {Jens Juul} and Timo Ravensbergen and Holger Reimerdes and Bernd Schneider and Roman Schrittwieser and Monica Spolaore and Kevin Verhaegh and Jose Vicente and Nick Walkden and Wei Zhang and Elisabeth Wolfrum",
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pages = "396--397",
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address = "Austria",

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Hakola, A, Vianello, N, Carralero, D, Tsui, C, Naulin, V, Agostini, M, Boedo, J, Labit, B, Theiler, C, Aguiam, D, Allan, S, Bernert, M, Costea, S, Cziegler, I, de Oliveira, H, Galdon-Quiroga, J, Grenfell, G, Ionita, C, Isliker, H, Karpushov, A, Kovacic, J, Lipschultz, B, Maurizio, R, McClements, K, Militello, F, Olsen, J, Rasmussen, JJ, Ravensbergen, T, Reimerdes, H, Schneider, B, Schrittwieser, R, Spolaore, M, Verhaegh, K, Vicente, J, Walkden, N, Zhang, W & Wolfrum, E 2018, SOL Transport and Filamentary Dynamics in High Density Tokamak Regimes. in 27th IAEA Fusion Energy Conference: Programme and Abstracts. International Atomic Energy Agency IAEA, pp. 396-397, 27th IAEA Fusion Energy Conference, FEC 2018, Ahmedabad, India, 22/10/18.

SOL Transport and Filamentary Dynamics in High Density Tokamak Regimes. / Hakola, Antti; Vianello, Nicola (Corresponding author); Carralero, Daniel; Tsui, Cedric; Naulin, Volker; Agostini, Matteo; Boedo, J; Labit, Benoit; Theiler, Christian; Aguiam, Diego; Allan, Scott; Bernert, Matthias; Costea, Stefan; Cziegler, Istvan; de Oliveira, Hugo; Galdon-Quiroga, Joaquin; Grenfell, Gustavo; Ionita, Codrina; Isliker, Heinz; Karpushov, Alexander; Kovacic, Jernej; Lipschultz, Bruce; Maurizio, Roberto; McClements, Ken; Militello, Fulvio; Olsen, Jeppe; Rasmussen, Jens Juul; Ravensbergen, Timo; Reimerdes, Holger; Schneider, Bernd; Schrittwieser, Roman; Spolaore, Monica; Verhaegh, Kevin; Vicente, Jose; Walkden, Nick; Zhang, Wei; Wolfrum, Elisabeth.

27th IAEA Fusion Energy Conference: Programme and Abstracts. International Atomic Energy Agency IAEA, 2018. p. 396-397.

Research output: Chapter in Book/Report/Conference proceedingConference abstract in proceedingsScientific

TY - CHAP

T1 - SOL Transport and Filamentary Dynamics in High Density Tokamak Regimes

AU - Hakola, Antti

AU - Vianello, Nicola

AU - Carralero, Daniel

AU - Tsui, Cedric

AU - Naulin, Volker

AU - Agostini, Matteo

AU - Boedo, J

AU - Labit, Benoit

AU - Theiler, Christian

AU - Aguiam, Diego

AU - Allan, Scott

AU - Bernert, Matthias

AU - Costea, Stefan

AU - Cziegler, Istvan

AU - de Oliveira, Hugo

AU - Galdon-Quiroga, Joaquin

AU - Grenfell, Gustavo

AU - Ionita, Codrina

AU - Isliker, Heinz

AU - Karpushov, Alexander

AU - Kovacic, Jernej

AU - Lipschultz, Bruce

AU - Maurizio, Roberto

AU - McClements, Ken

AU - Militello, Fulvio

AU - Olsen, Jeppe

AU - Rasmussen, Jens Juul

AU - Ravensbergen, Timo

AU - Reimerdes, Holger

AU - Schneider, Bernd

AU - Schrittwieser, Roman

AU - Spolaore, Monica

AU - Verhaegh, Kevin

AU - Vicente, Jose

AU - Walkden, Nick

AU - Zhang, Wei

AU - Wolfrum, Elisabeth

PY - 2018/10

Y1 - 2018/10

N2 - Addressing the role of scrape off layer filamentary transport is a subject of intense studies in fusion science. Intermittent structures dominate transport in L-Mode and strongly contribute to particle and energy losses in H-mode. The role of convective radial losses has become even more important due to its contribution to the shoulder formation in L-Mode, describing the progressive flattening of the density scrape off layer profile at high density [1]. Investigation of this process revealed the strong relationship between divertor conditionsand the upstream profiles, mediated by filaments dynamics which varies according to the downstream conditions. Preliminary investigations suggested that similar mechanisms occur in H-Mode [1] and that filaments contribute the SOL transport in H-mode density limit (HDL) as well [4]. The present contribution will report on results obtained on ASDEX-Upgrade and TCV tokamaks, to address the role of filamentary transport in high density regimes both in L- and H-Mode. The combined results enlarge the operational space, from a device with a closed divertor, metallic first wall and cryogenic pumping system to a carbon machine with a completely open divertor. The mechanism of shoulder formationand the role of filaments have been tested against variation of plasma current, magnetic configuration (single and double null plasmas), and divertor neutral densities, through modification of cryopump efficiency. At constant magnetic field the density decay length increases with filament-size independently of the plasma current for both machines in L-mode, consistently with the fact that upstream profiles and divertor neutral pressure exhibit the same trend with normalized Greenwald fraction.In H-Mode fuelling is insufficient to cause flattening of SOL profiles in the inter-ELM phases since large neutral pressure is needed. Consistently inter-ELM blob size in AUG are found larger whenever the cryopumps is switched off. The resulting picture suggests a complex relationship between divertor and upstream profiles, where filaments are modified by divertor conditions as well as by neutral particles interaction.

AB - Addressing the role of scrape off layer filamentary transport is a subject of intense studies in fusion science. Intermittent structures dominate transport in L-Mode and strongly contribute to particle and energy losses in H-mode. The role of convective radial losses has become even more important due to its contribution to the shoulder formation in L-Mode, describing the progressive flattening of the density scrape off layer profile at high density [1]. Investigation of this process revealed the strong relationship between divertor conditionsand the upstream profiles, mediated by filaments dynamics which varies according to the downstream conditions. Preliminary investigations suggested that similar mechanisms occur in H-Mode [1] and that filaments contribute the SOL transport in H-mode density limit (HDL) as well [4]. The present contribution will report on results obtained on ASDEX-Upgrade and TCV tokamaks, to address the role of filamentary transport in high density regimes both in L- and H-Mode. The combined results enlarge the operational space, from a device with a closed divertor, metallic first wall and cryogenic pumping system to a carbon machine with a completely open divertor. The mechanism of shoulder formationand the role of filaments have been tested against variation of plasma current, magnetic configuration (single and double null plasmas), and divertor neutral densities, through modification of cryopump efficiency. At constant magnetic field the density decay length increases with filament-size independently of the plasma current for both machines in L-mode, consistently with the fact that upstream profiles and divertor neutral pressure exhibit the same trend with normalized Greenwald fraction.In H-Mode fuelling is insufficient to cause flattening of SOL profiles in the inter-ELM phases since large neutral pressure is needed. Consistently inter-ELM blob size in AUG are found larger whenever the cryopumps is switched off. The resulting picture suggests a complex relationship between divertor and upstream profiles, where filaments are modified by divertor conditions as well as by neutral particles interaction.

M3 - Conference abstract in proceedings

SP - 396

EP - 397

BT - 27th IAEA Fusion Energy Conference

PB - International Atomic Energy Agency IAEA

ER -

Hakola A, Vianello N, Carralero D, Tsui C, Naulin V, Agostini M et al. SOL Transport and Filamentary Dynamics in High Density Tokamak Regimes. In 27th IAEA Fusion Energy Conference: Programme and Abstracts. International Atomic Energy Agency IAEA. 2018. p. 396-397