Linear Z(eff) scaling of the anomalous inward drift and enhanced proportionality factor during neon inflow

The origin of density profile peaking due to impurity puffing and the anomalous particle pinch are explored by computer simulations with special versions of the 1.5-D BALDUR predictive transport code. Transport analysis of high density H mode plasmas with strong neon puffing and density profile peaking yields a new scaling law for the anomalous inward drift velocity, v(in)(x) = C(v)2xD(x)/(rho(w)x(s)(2)), with C-v = FZ(eff)(x), where D is the diffusion coefficient. This scaling implies that v(in)/D alpha Z(eff) and results in v(in) alpha Z(eff), since D is found to be independent of this parameter. The strong density profile peaking is caused by the increase in Z(eff) and by an enhanced factor F discovered during neon puffing. The time evolution of F correlates with the neon influx rate, but not with the neon content and the power losses due to line radiation and ionization. The factor F rises with growing influx rate and depends non-locally on the region where inelastic collisions prevail. One plausible mechanism for the enhancement of F is that inelastic collisions between fluctuating electrons and impurity ions change the dissipative part of the fluctuating electron distribution.