Alcator C-MOD Mini-Proposal Subject : Impurity Screening : Divertor Compression and the Role of Core Impurity Confinement MP No . 167 From :

The purpose of this experiment is to try and answer several questions that have been raised by previous experiments: (1) When recycling impurities are injected, only a small fraction are found in the core plasma. Where do the rest of the injected atoms go? To the divertor? To the wall? We will try to use this technique for non-recycling impurities and He as well. (2) The penetration factor (PF) for nitrogen was found to be poorer in H-mode plasmas than for L-mode (typically ohmic) plasmas. How much of this difference is due to changes in core impurity transport? What about Ne? We will begin intrinsic impurity transport screening studies by monitoring the source rates at the divertor and limiter surfaces as well as the core molybdenum levels. Source rates of Mo and recycled injected particles will be monitored at limiter and divertor surfaces for use in impurity transport modeling (DIVIMP).