Recent DiMES PMI research in the DIII-D tokamak*

The Divertor Material Evaluation System (DiMES) is a versatile platform and the main tool for Plasma-Material Interactions (PMI) studies at the DIII-D tokamak. The DiMES manipulator allows exposing material samples and collector probes (CPs) in the lower divertor of DIII-D under well-controlled plasma conditions with extensive diagnostic coverage. Tests of various Plasma Facing Materials (PFMs) such as different grades of tungsten and W-W composites, SiC and advanced ceramic materials are performed to study gross/net erosion, surface morphology modification under reactor-relevant heat loads and hydrogenic retention. By using spectroscopy and post-mortem Ion Beam Analysis for erosion measurements, S/XB coefficients for various spectral lines are calibrated. DiMES CPs are used in support of traditional boronization and real-time wall conditioning by boron and silicon powder dropping into plasmas. Tests of lithium-filled Capillary Porous System and self-extruding pebble rod PFM concepts are planned. A DiMES head equipped with an array of thermoluminescent dosimeters will be used to measure the pitch angle of runaway electrons impacting the divertor surface. DiMES program strength is largely in its multiple collaborators, and we will welcome new ones, including those from the private sector.