Page 7 - Outer Divertor Damage Characterization from Deuterium Plasma Bombardment in Graphene-Coated Tungsten

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NAVARRO et al. · OUTER DIVERTOR DAMAGE CHARACTERIZATION FROM DEUTERIUM PLASMA BOMBARDMENT
Fig. 7. (a) Preexposure image of bare tungsten sample (W2). (b) Low-magnification image of postexposure surface of bare tungsten. (c) High-magnification image of postexposure surface of bare tungsten. (d) Preexposure image of graphene-coated tungsten sample (W6). (e) Low-magnification image of postexposure surface of graphene-coated tungsten. (f) High-magnification image of postexposure surface of graphene-coated tungsten. It is clear that graphene has a significant effect on the surface morphology after irradiation.
time intervals of each discharge. Deuterium plasma
exposures introduce single-vacancy defects in the graphene
but do not push the membrane to failure at a fluence of
18 + 2
1.1 × 10 D /cm . Although the fluences to which these
samples are exposed are a few orders of magnitude lower than expected fluences in fully operational fusion reactors, the small increase in the damage ratio of the membrane leaves significant room for exploring the higher-fluence regimes that will be of interest for the design of divertor plates or the plasma first wall. A more detailed parametric study will prove useful for exploring different regimes for
devices that operate with limiters or divertors and detached or limited plasmas. These results could begin to pave the way for more detailed studies regarding new PFC candidates in multiple plasma devices.
Acknowledgments
The authors wish to acknowledge the financial support for this work from TAE Technologies and the Grainger Foundation. The work of M. Zamiri and M. Lagally was supported by the U.S.
FUSION SCIENCE AND TECHNOLOGY · VOLUME 75 · AUGUST 2019