DiMES PMI research at DIII-D in support of ITER and beyond

• Published in: Fusion engineering and design 2017-03, Vol.124 (C)
• Main Authors: Rudakov, Dimitry L., Abrams, Tyler, Ding, Rui, Guo, Houyang Y., Stangeby, Peter C., Wampler, William R., Boedo, Jose A., Briesemeister, Alexis R., Brooks, J. N., Buchenauer, Dean A., Bykov, Igor, Chrobak, Chris, Doerner, R. P., Donovan, David C., Elder, J. David, Fenstermacher, Max E., Guterl, Jerome, Hinson, Edward T., Hollmann, Eric M., Lasnier, Charles J., Leonard, Anthony W., McLean, Adam G., Moyer, Richard A., Nygren, R. E., Thomas, Dan M., Unterberg, Ezekial A., Watkins, Jonathan G., Wong, C. P. C.
• Format: Article
• Language: English
• Subjects: 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; DIII-D tokamak; DiMES; Plasma-facing components; Plasma-material interactions
• ISSN: 0920-3796; 1873-7196
• DOI: 10.1016/j.fusengdes.2017.03.007

An overview of recent Plasma-Material Interactions (PMI) research at the DIII-D tokamak using the Divertor Material Evaluation System (DiMES) is presented. The DiMES manipulator allows for exposure of material samples in the lower divertor of DIII-D under well-diagnosed ITER-relevant plasma conditions. Plasma parameters during the exposures are characterized by an extensive diagnostic suite including a number of spectroscopic diagnostics, Langmuir probes, IR imaging, and Divertor Thomson Scattering. Post-mortem measurements of net erosion/deposition on the samples are done by Ion Beam Analysis, and results are modelled by the ERO and REDEP/WBC codes with plasma background reproduced by OEDGE/DIVIMP modelling based on experimental inputs. This article highlights experiments studying sputtering erosion, re-deposition and migration of high-Z elements, mostly tungsten and molybdenum, as well as some alternative materials. Results are generally encouraging for use of high-Z PFCs in ITER and beyond, showing high redeposition and reduced net sputter erosion. Furthermore, two methods of high-Z PFC surface erosion control, with (i) external electrical biasing and (ii) local gas injection, are also discussed. These techniques may find applications in the future devices.