Impurity transport studies in tokamak edge plasmas using visible imaging

Understanding impurity transport in the scrape-off layer (SOL) of tokamak plasmas is a necessary piece of developing the physics basis for designing next-generation reactors. A system for inferring impurity transport parallel and perpendicular to local magnetic field lines has been developed on Alcator C-Mod using gas-injection "plumes." In this system, impurity gas is injected at a fixed position in the SOL via a reciprocating fast-scanning probe, and the resulting emission is imaged. In this paper, visible light emission patterns from C/sup +1/ and C/sup +2/ ions are presented.