Modeling snowflake divertors in MAST-U Tokamak

A. I. Khrabry, V. A. Soukhanovskii, T. D. Rognlien, M. V. Umansky, D. Moulton, J. R. Harrison

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


In a snowflake (SF) divertor, two magnetic field nulls are placed close to each other, creating four strike points (SPs) compared to two in a standard X-point divertor. In preparation for MAST-U experiments, magnetic configurations with the standard and SF divertors with various locations and separation distances of the nulls were modeled using the two-dimensional multi-fluid code UEDGE with a full plasma transport model featuring charge-state-resolved sputtered carbon impurities. The complex interplay of the plasma transport and magnetic configurations was comprehensively studied using a simple model for the theoretically predicted fast plasma mixing driven by the 'churning' mode instability in the two-null SF region. The modeling results show that (1) all SF-plus configurations and SF-minus configuration with closely located nulls produce the same plasma parameters and heat fluxes at the same SPs; (2) SF divertors approach the outer and inner SP detachment conditions at lower upstream density w.r.t. the standard divertor; (3) heat flux profiles at primary SPs are substantially broadened and peak values are reduced in SF configurations w.r.t. SN divertors; this broadening becomes more pronounced with the fast plasma mixing increase.

Original languageEnglish (US)
Article number016007
JournalNuclear Fusion
Issue number1
StatePublished - Jan 2022
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics
  • Condensed Matter Physics


  • advanced divertor
  • churning mode
  • MAST-U
  • multi-fluid modeling
  • snowflake divertor


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