DIII-D RESEARCH OPPORTUNITIES FORUM FOR THE 2013 EXPERIMENTAL CAMPAIGN Review | Direct submission with log-in | Request submission without log-in
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Title	215: Control of tungsten PFC erosion by local gas injection
Name:	Dmitry Rudakov rudakov@fusion.gat.com	Affiliation:	University of California, San Diego
Research Area:	Plasma-material Interface	Presentation time:	Not requested
Co-Author(s):	C.P.C. Wong, P.C. Stangeby, O. Buzhinskij	ITPA Joint Experiment :	No
Description:	Use local gas injection nearby DiMES to deposit a sacrificial low-Z coating on top of a tungsten PFC surface in order to protect tungsten from erosion.	ITER IO Urgent Research Task :	No
Experimental Approach/Plan:	A graphite DiMES sample with deposited W layer will be used for the experiment. Non-toxic, non-explosive metacarborane C2H12B10 will be injected through a gas line opening nearby DiMES. Partially detached H-mode plasma conditions will be used, that would normally result in measurable tungsten erosion during ELMs. The hope is that the coating deposited on the tungsten surface between ELMs will protect the surface from erosion. A second experiment without gas injection may be needed for comparison.
Background:	Tungsten is a leading PFC candidate material for ITER divertor and for devices beyond ITER. While erosion of tungsten under detached plasma conditions should be very small, transients such as large ELMs and disruptions can lead to a substantial erosion and surface damage including melting. Sputtered tungsten entering the plasma core would lead to unacceptably high radiation losses. If a sacrificial low-Z coating is deposited on top of W surface, it can protect surface from erosion and prevent core contamination with high-Z impurities. However, a thin coating will be quickly eroded, so it has to be renewable in-situ, preferably during a plasma discharge. We propose a proof-of-principle experiment, where a low-Z coating would be deposited on top of W-coated DiMES sample by local gas injection.
Resource Requirements:	One or two 1/2 day experiment(s), partially detached LSN H-mode with OSP near DiMES
Diagnostic Requirements:	All available lower divertor diagnostics, DiMES, core and divertor Thomson, CER with C and B lines. IRTV view of DiMES highly desirable.
Analysis Requirements:	--
Other Requirements:	--