"Snowflake" divertor configuration in NSTX

V. A. Soukhanovskii, J. W. Ahn, R. E. Bell, D. A. Gates, S. Gerhardt, R. Kaita, E. Kolemen, H. W. Kugel, B. P. Leblanc, R. Maingi, R. Maqueda, A. McLean, J. E. Menard, D. M. Mueller, S. F. Paul, R. Raman, A. L. Roquemore, D. D. Ryutov, H. A. Scott

Research output: Contribution to journalArticlepeer-review

28 Scopus citations


Steady-state handling of divertor heat flux is a critical issue for present and future conventional and spherical tokamaks with compact high power density divertors. A novel "snowflake" divertor (SFD) configuration that takes advantage of magnetic properties of a second-order poloidal null has been predicted to have a larger plasma-wetted area and a larger divertor volume, in comparison with a standard first-order poloidal X-point divertor configuration. The SFD was obtained in 0.8 MA, 4-6 MW NBI-heated H-mode discharges in NSTX using two divertor magnetic coils. The SFD led to a partial detachment of the outer strike point even in low-collisionality scrape-off layer plasma obtained with lithium coatings in NSTX. Significant divertor peak heat flux reduction and impurity screening have been achieved simultaneously with good core confinement and MHD properties.

Original languageEnglish (US)
Pages (from-to)S365-S368
JournalJournal of Nuclear Materials
Issue number1 SUPPL
StatePublished - Aug 1 2011

All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics
  • General Materials Science
  • Nuclear Energy and Engineering


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