Power exhaust in the snowflake divertor for L- and H-mode TCV tokamak plasmas

TitlePower exhaust in the snowflake divertor for L- and H-mode TCV tokamak plasmas
Publication TypeJournal Article
Year of Publication2014
AuthorsW.AJ Vijvers, G.P. Canal, B. Labit, H. Reimerdes, B. Tal, S. Coda, G.C De Temmerman, B.P Duval, T.W Morgan, J.J Zielinski
JournalNuclear Fusion
Date PublishedFeb
ISBN Number0029-5515; 1741-4326

The snowflake (SF) divertor is a plasma configuration that may enable tokamak operation at high performance and lower peak heat loads on the plasma-facing components than a standard single-null divertor. This paper reports on the results of experiments performed on the TCV tokamak in both the low- and high-confinement regimes, wherein the divertor configuration was continuously varied between a standard single-null and a 'SF-plus', which features auxiliary strike points (SPs) in the private flux region of the primary separatrix. The measured edge properties show that, in L-mode, the fraction of the exhaust power reaching the additional SPs is small. During edge-localized modes, up to similar to 20% of the exhausted energy is redistributed to the additional SPs even at an x-point separation of 0.6 times the plasma minor radius, thereby reducing the peak heat flux to the inner primary SP by a factor of 2-3. The observed behaviour is qualitatively consistent with a proposed model for enhanced cross-field transport through the SF's relatively large region of low poloidal field by instability-driven convection.



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