Effective ionic charge from visible bremsstrahlung measurements on EAST

On EAST, effective ionic charge was routinely computed from line integrated measurements of visible bremsstrahlung. Comparison between the value of effective ionic charge before and after boronization shows that the amount of impurities decreases a lot after boronization. Analysis on a large database of EAST experimental campaign 2009 shows strong linear relationship between effective ionic charge and line radiation of carbon, and the fitting factor varies from 3.4 to 5.8, depending on both plasma current and auxiliary power. The amount of main impurities were compared with each other through UV-VIS spectrum, and the result shows that carbon contributes the most to effective ionic charge than any other light impurities.