Modelling of mitigation of the power divertor loading for the EU DEMO through Ar injection

Fabio Subba, Leena Aho-Mantila, David Coster, Giorgio Maddaluno, Giuseppe F. Nallo, Bernard Sieglin, Ronald Wenninger, Roberto Zanino

Research output: Contribution to journalArticleScientificpeer-review

3 Citations (Scopus)

Abstract

In this paper we present a computational study on the divertor heat load mitigation through impurity injection for the EU DEMO. The study is performed by means of the SOLPS5.1 code. The power crossing the separatrix is considered fixed and corresponding to H-mode operation, whereas the machine operating condition is defined by the outboard mid-plane upstream electron density and the impurity level. The selected impurity for this study is Ar, based on its high radiation efficiency at SOL characteristic temperatures. We consider a conventional vertical target geometry for the EU DEMO and monitor target conditions for different operational points, considering as acceptability criteria the target electron temperature (≤5 eV to provide sufficiently low W sputtering rate) and the peak heat flux (below 5-10 MW m-2 to guarantee safe steady-state cooling conditions). Our simulations suggest that, neglecting the radiated power deposition on the plate, it is possible to satisfy the desired constraints. However, this requires an upstream density of the order of at least 50% of the Greenwald limit and a sufficiently high argon fraction. Furthermore, if the radiated power deposition is taken into account, the peak heat flux on the outer plate could not be reduced below 15 MW m-2 in these simulations. As these simulations do not take into account neutron loading, they strongly indicate that the vertical target divertor solution with a radiative front distributed along the divertor leg has a very marginal operational space in an EU DEMO sized reactor.

Original languageEnglish
Article number035013
JournalPlasma Physics and Controlled Fusion
Volume60
Issue number3
DOIs
Publication statusPublished - 5 Feb 2018
MoE publication typeA1 Journal article-refereed

Fingerprint

Impurities
injection
Heat flux
impurities
upstream
heat flux
Electron temperature
Thermal load
Carrier concentration
Sputtering
simulation
Argon
Neutrons
acceptability
Cooling
monitors
Radiation
Geometry
sputtering
reactors

Keywords

  • demo
  • divertor protection
  • modelling
  • radiative scenarios
  • SOLPS
  • tokamak

Cite this

Subba, Fabio ; Aho-Mantila, Leena ; Coster, David ; Maddaluno, Giorgio ; Nallo, Giuseppe F. ; Sieglin, Bernard ; Wenninger, Ronald ; Zanino, Roberto. / Modelling of mitigation of the power divertor loading for the EU DEMO through Ar injection. In: Plasma Physics and Controlled Fusion. 2018 ; Vol. 60, No. 3.
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Modelling of mitigation of the power divertor loading for the EU DEMO through Ar injection. / Subba, Fabio; Aho-Mantila, Leena; Coster, David; Maddaluno, Giorgio; Nallo, Giuseppe F.; Sieglin, Bernard; Wenninger, Ronald; Zanino, Roberto.

In: Plasma Physics and Controlled Fusion, Vol. 60, No. 3, 035013, 05.02.2018.

Research output: Contribution to journalArticleScientificpeer-review

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AU - Subba, Fabio

AU - Aho-Mantila, Leena

AU - Coster, David

AU - Maddaluno, Giorgio

AU - Nallo, Giuseppe F.

AU - Sieglin, Bernard

AU - Wenninger, Ronald

AU - Zanino, Roberto

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AB - In this paper we present a computational study on the divertor heat load mitigation through impurity injection for the EU DEMO. The study is performed by means of the SOLPS5.1 code. The power crossing the separatrix is considered fixed and corresponding to H-mode operation, whereas the machine operating condition is defined by the outboard mid-plane upstream electron density and the impurity level. The selected impurity for this study is Ar, based on its high radiation efficiency at SOL characteristic temperatures. We consider a conventional vertical target geometry for the EU DEMO and monitor target conditions for different operational points, considering as acceptability criteria the target electron temperature (≤5 eV to provide sufficiently low W sputtering rate) and the peak heat flux (below 5-10 MW m-2 to guarantee safe steady-state cooling conditions). Our simulations suggest that, neglecting the radiated power deposition on the plate, it is possible to satisfy the desired constraints. However, this requires an upstream density of the order of at least 50% of the Greenwald limit and a sufficiently high argon fraction. Furthermore, if the radiated power deposition is taken into account, the peak heat flux on the outer plate could not be reduced below 15 MW m-2 in these simulations. As these simulations do not take into account neutron loading, they strongly indicate that the vertical target divertor solution with a radiative front distributed along the divertor leg has a very marginal operational space in an EU DEMO sized reactor.

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