PSFC/JA-04-31 DIVIMP modeling of impurity flows and screening in Alcator C-Mod

We report on impurity transport modeling using the DIVIMP code which is able to qualitatively reproduce the poloidal variation of non-recycling impurity penetration factor (PFNR) found in CMod experiments: a lower PFNR is computed at the inboard (3.6 %) and divertor target locations (0.7 %) than at the outboard (11 %). By artificially increasing the modeled inner SOL plasma flow to correspond to measured values, a better quantitative agreement between modeled and measured PFs is achieved. We have also roughly reproduced the observed penetration factor for recycling impurities both in time dependence and magnitude. The model has shown that under attached conditions, the majority of recycling impurity ions flow into the confined plasma through the outboard side separatrix. For detached conditions the impurity influx across the separatrix is more concentrated near the divertor. _____________________________________________ PACS: 52.55.F, 52.65.K, 52.25.V JNM keywords: Impurities (I0100), Plasma-Materials Interaction (P0500) PSI-16 keywords: Alcator C-Mod, DIVIMP, Recycling, Impurity screening *Corresponding author address: 175 Albany St. NW17-103, Cambridge, MA 02139, USA *Corresponding author E-mail: [email protected] *Corresponding Author Phone/FAX: 1-617-253-8636, 1-617-253-0627 *Corresponding Author: Bruce Lipschultz