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  4. Modelling of sawtooth-induced fast ion transport in positive and negative triangularity in TCV
 
research article

Modelling of sawtooth-induced fast ion transport in positive and negative triangularity in TCV

Vallar, Matteo  
•
Podesta, Mario  
•
Baquero-Ruiz, Marcelo  
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February 1, 2022
Nuclear Fusion

Internal kinks are a common magneto hydro-dynamic (MHD) instability observed in tokamak operation when the q profile in the plasma core is close to unity. This MHD instability impacts both the transport of the bulk plasma (current, particle and energy transport) and minority species, such as fast ions. In tokamak a configuration variable (TCV) (R (0)/a = 0.88 m/0.25 m) the fast ion population is generated in the plasma by neutral beam tangential injection of energies up to 28 keV. TCV features 16 active shaping coils permitting a great flexibility in plasma shape, including negative triangularity (delta) configurations that show surprisingly high confinement. This study focuses on the transport of fast ions induced by sawteeth, by comparing two triangularity cases and simulation results with experimental data. Comparison of two equilibria with opposite delta shows that the fast ion drifts are larger for delta < 0. Furthermore, the sawtooth-induced transport in this case is larger than delta > 0 in similar conditions. Comparison with experimental data confirms the dominance of the modification of thermal kinetic profiles following the sawtooth crash in explaining drops in the neutron rates and fast ion D-alpha signals. Additional fast ion diffusion, however, improves the interpretation of the experimental data. For delta < 0, the amplitude of the perturbation better representing the experimental data is larger. Finally, an exploratory study for 50 keV particles (soon available in TCV) shows that the situation does not worsen for such particles.

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Type
research article
DOI
10.1088/1741-4326/ac3f18
Web of Science ID

WOS:000739041100001

Author(s)
Vallar, Matteo  
Podesta, Mario  
Baquero-Ruiz, Marcelo  
Bonofiglo, Phillip
Duval, Basil P.  
Karpushov, Alexander N.  
Merle, Antoine  
Mykytchuk, Dmytry  
Sauter, Olivier  orcid-logo
Stipani, Lorenzo  
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Date Issued

2022-02-01

Publisher

IOP Publishing Ltd

Published in
Nuclear Fusion
Volume

62

Issue

2

Article Number

026028

Subjects

Physics, Fluids & Plasmas

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Physics

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negative triangularity

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fast ions

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tcv

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sawteeth

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kick-model

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anomalous diffusion

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tokamak

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magnetic sensors

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oscillations

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code

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alpha

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stability

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plasmas

Editorial or Peer reviewed

REVIEWED

Written at

EPFL

EPFL units
SPC  
Available on Infoscience
January 31, 2022
Use this identifier to reference this record
https://infoscience.epfl.ch/handle/20.500.14299/184948
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