Enhanced (E)over-right-arrow x (B)over-right-arrow drift effects in the TCV snowflake divertor

Measurements of various plasma parameters at the divertor targets of snowflake (SF) and conventional single-null configurations indicate an enhanced effect of the (E) over right arrow x (B) over right arrow drift in the scrape-off layer of plasmas in the SF configuration. Plasma boundary transport simulations using the EMC3-Eirene code show that the poloidal gradients of the kinetic profiles in the vicinity of the null-point of a SF divertor are substantially larger than those of a conventional single-null configuration. These gradients are expected to drive larger (E) over right arrow x (B) over right arrow flows in the SF divertor and are thought to be responsible for the formation of the double-peaked particle and heat flux target profiles observed experimentally. Experiments in forward and reversed toroidal magnetic field directions further support this conclusion. The formation of such a double-peaked profiles is enhanced at higher plasma densities and may have beneficial effects on the divertor heat loads since they lead to broader target profiles and lower peak heat fluxes.

Published in:
Nuclear Fusion, 55, 12, 123023
Bristol, Iop Publishing Ltd

 Record created 2016-02-16, last modified 2018-01-28

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