Quantification of main wall erosion/deposition pattern in n = 2 RMP KSTAR H-mode plasmas

Abstract

Erosion/deposition pattern was studied using cavity sample at KSTAR main wall region. The cavity sample has a different two slit opening directions. The amorphous carbon film inside the cavity structure was installed on mid-plane manipulator system and was exposed to H-mode plasmas with n = 2 RMP. The most of characterized amorphous hydrocarbon film in cavity structure was eroded after exposing to H-mode plasmas. The erosion rate of bottom plate sample was in a range from 0.32 nm s−1 to 0.77 nm s−1 in a different slit opening directions, respectively. But the upper samples were deposited and the maximum deposition rate of it was 0.42 nm s−1. Thickness profiles measured by ellipsometer were compared with simulated profile using Monte Carlo Ballistic Simulation. The main parameter for simulation was the incident angle of particle. The incident angle of particle influenced the shape and width of simulated profile. The incident angle used in simulation was in the range of 80°–89° and it was well matched with 81.9° derived from EFIT.