High-Z material erosion and its control in DIII-D carbon divertor. (August 2017)

• Record Type: Journal Article
• Authors: Ding, R.; Rudakov, D.L.; Stangeby, P.C.; Wampler, W.R.; Abrams, T.; Brezinsek, S.; Briesemeister, A.; Bykov, I.; Chan, V.S.; Chrobak, C.P.; Elder, J.D.; Guo, H.Y.; Guterl, J.; Kirschner, A.; Lasnier, C.J.; Leonard, A.W.; Makowski, M.A.; McLean, A.G.; Snyder, P.B.; Thomas, D.M.; Tskhakaya, D.; Unterberg, E.A.; Wang, H.Q.; Watkins, J.G.
• Is Part Of: Nuclear materials and energy. Volume 12(2017)
• Page Start: 247
• Page End: 252
• Publication Date: 2017-08
• Subjects: Nuclear energy -- Periodicals; Nuclear fuels -- Periodicals; Nuclear reactors -- Materials -- Periodicals; Radioactive substances -- Periodicals; 621.4833
• DOI: 10.1016/j.nme.2017.03.012
• Languages: English
• ISSNs: 2352-1791

Abstract

Highlights: Dedicated DIII-D experiments coupled with ERO modeling deepen our understanding of high-Z material erosion and re-deposition. The sheath properties and carbon impurities play a critical role in determining high-Z materials erosion. The high-Z material erosion has been successfully suppressed by local gas puffing. Abstract: As High-Z materials will likely be used as plasma-facing components (PFCs) in future fusion devices, the erosion of high-Z materials is a key issue for high-power, long pulse operation. High-Z material erosion and redeposition have been studied using tungsten and molybdenum coated samples exposed in well-diagnosed DIII-D divertor plasma discharges. By coupling dedicated experiments and modelling using the 3D Monte Carlo code ERO, the roles of sheath potential and background carbon impurities in determining high-Z material erosion are identified. Different methods suggested by modelling have been investigated to control high-Z material erosion in DIII-D experiments. The erosion of Mo and W is found to be strongly suppressed by local injection of methane and deuterium gases. The 13 C deposition resulting from local 13 CH4 injection also provides information on radial transport due toE × B drifts and cross field diffusion. Finally, D2 gas puffing is found to cause local plasma perturbation, suppressing W erosion because of the lower effective sputtering yield of W at lower plasma temperature and for higher carbon concentration in the mixed surface layer.