Experimental study of heating scheme effect on the inner divertor power footprint widths in EAST lower single null discharges

Thedivertor power footprint widths, i.e., the scrape-off layer heat flux decay length λ q and the heatspreading S, are crucial physical and engineering parameters for fusion reactors. Strong inversescaling of λ q and S with plasma current have been demonstrated for both neutral beam (NB) andlower hybrid wave (LHW) heated L-mode and H-mode plasmas at the inner divertor target.

Forplasmas heated by the combination of the two kinds of auxiliary heating schemes (NB and LHW),the divertor power widths tend to be larger in plasmas with higher ratio of LHW power. Comparisonbetween experimental heat flux profiles at outer mid-plane (OMP) and divertor target for NB heatedand LHW heated L-mode plasmas reveals that the magnetic topology changes induced by LHW maybe the main reason to the wider divertor power widths in LHW heated discharges.