Separatrix density scaling in JET with the ITER-like wall

The electron separatrix density, n_e,sep, in JET-ILW L-mode and H-mode unseeded plasmas exhibits a strong dependence on the averaged outer divertor target electron temperature, n_e,sep ∝〈T_e,ot〉^-1/2, arising from parallel pressure balance, as well as on the ratio of the power and momentum volumetric loss factors, in line with expectation from the reversed two point model (rev-2PM). Rev-2PM n_e,sep estimates are recovered to within ±25% of the measurements, with a scaling factor applied to account for use of 〈T_e,ot〉, an averaged quantity, rather than flux tube resolved target values. Both the volumetric loss factor trends and recovery of n_e,sep using the rev-2PM formatting are reproduced in EDGE2D-EIRENE L-mode-like and H-mode-like density scan simulations. Main chamber recycling likely plays a significant role in moderating the influence of divertor closure changes on neutral leakage from the divertor and the n_e,sep trends. In the inner vertical, outer horizontal divertor configuration with significantly reduced clearance to the high-field side separatrix, the more pronounced high-field side high density region formation has no clear impact on the outer midplane n_e,sep and n_e,ped trends, and hence does not appear to play a strong role in fueling the outer midplane confined plasma.