|Title||Power exhaust in the snowflake divertor for L- and H-mode TCV tokamak plasmas|
|Publication Type||Journal Article|
|Year of Publication||2014|
|Authors||W.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|
|ISBN Number||0029-5515; 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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