Study of H-mode pedestal model for helium plasmas in DIII-D

Helium (He) plasmas will be used to test the operationally relevant systems and plasma diagnostics during the ITER non-nuclear phase. Analyses of pedestal width and height in recent DIII-D H-mode experiments in He plasmas find good agreement with Δ ψ = 0.095 β p , ped 1 / 2 between the pedestal width Δ ψ and the square root of the poloidal pedestal beta β p , ped 1 / 2 from experimental observations. The EPED/REPED pedestal model is found to be applicable to predict the pedestal structure of the He plasma from comparison of predictions with experiments. Furthermore, it indicates that the pedestal height of He and deuterium (D) plasmas are similar from the REPED predictions with the same global parameters, and the pedestal width of He is approximately 6% larger than that of D.