The effect of field reversal on the JET MkIIGB-SRP divertor performance in L-mode density limit discharges

The effect of field reversal on the JET MkIIGB-SRP divertor performance has been investigated in L-mode density limit discharges. These experiments show that the direction of the magnetic field has a substantial effect on divertor physics, modifying the character of detachment and density limits. Reversal of the ion ∇B-drift direction away from the X-point results in a reduction of the density limit of about 15%. In contrast to forward field direction, the divertor parameters such as density and temperature as well as divertor radiation distribution and power at the divertor target become more symmetrical in the discharges with reversed field. The influence of different field configurations on the divertor performance has been analysed with respect to the dependence on density and heating power. The experimental observations of out-in asymmetry in target power as well as in the CIII-emission distribution is consistent with EDGE2D simulations, which include the effect of drifts.