Measurement and Analysis of Z_eff in the C-2W Field-Reversed Configuration Plasma Experiment

The effective ionic charge (Z_eff) is an important parameter which serves as a quantitative proxy for impurity levels in fusion plasmas. A study of the spatial and temporal evolution of Z_eff helps elucidate the mechanisms that drive impurity generation and transport. In C-2W, Z_eff is determined from measurements of visible and near-infrared bremsstrahlung light. Balmer-alpha (D_α) neutral detectors are utilized for pollutant removal. In this work, Z_eff behavior for different machine settings and wall conditioning experiments are investigated and discussed.