Impact of divertor geometry on radiative divertor performance in JET H-mode plasmas

Research output: Contribution to journalArticleScientificpeer-review

Researchers

  • Aaro Järvinen
  • S. Brezinsek
  • C. Giroud
  • Mathias Groth

  • C. Guillemaut
  • P. Belo
  • M. Brix
  • G. Corrigan
  • P. Drewelow
  • D. Harting
  • A. Huber
  • K. D. Lawson
  • B. Lipschultz
  • C. F. Maggi
  • G. F. Matthews
  • A. G. Meigs
  • D. Moulton
  • M. F. Stamp
  • S. Wiesen
  • JET contributors

Research units

  • Culham Science Centre
  • Jülich Research Centre
  • Instituto Superior Tecnico Lisboa
  • Max-Planck-Institut für Plasmaphysik
  • University of York

Abstract

Radiative divertor operation in JET high confinement mode plasmas with the ITER-like wall has been experimentally investigated and simulated with EDGE2D-EIRENE in horizontal and vertical low field side (LFS) divertor configurations. The simulations show that the LFS divertor heat fluxes are reduced with N2-injection in similar fashion in both configurations, qualitatively consistent with experimental observations. The simulations show no substantial difference between the two configurations in the reduction of the peak LFS heat flux as a function of divertor radiation, nitrogen concentration, or pedestal Zeff. Consistently, experiments show similar divertor radiation and nitrogen injection levels for similar LFS peak heat flux reduction in both configurations. Nevertheless, the LFS strike point is predicted to detach at 20% lower separatrix density in the vertical than in the horizontal configuration. However, since the peak LFS heat flux in partial detachment in the vertical configurations is shifted towards the far scrape-off layer (SOL), the simulations predict no benefit in the reduction of LFS peak heat flux for a given upstream density in the vertical configuration relative to a horizontal one. A factor of 2 reduction of deuterium ionization source inside the separatrix is observed in the simulations when changing to the vertical configuration. The simulations capture the experimentally observed particle and heat flux reduction at the LFS divertor plate in both configurations, when adjusting the impurity injection rate to reproduce the measured divertor radiation. However, the divertor D α-emissions are underestimated by a factor of 2-5, indicating a short-fall in radiation by the fuel species. In the vertical configuration, detachment is experimentally measured and predicted to start next to the strike point, extending towards the far SOL with increasing degree of detachment. In contrast, in the horizontal configuration, the entire divertor particle flux profile is reduced uniformly with increasing degree of detachment.

Details

Original languageEnglish
Article number045011
Pages (from-to)1-19
Number of pages19
JournalPlasma Physics and Controlled Fusion
Volume58
Issue number4
Publication statusPublished - Apr 2016
MoE publication typeA1 Journal article-refereed

    Research areas

  • detachment, divertor, EDGE2D-EIRENE, geometry, impurity seeding, JET, radiation

ID: 2103768