[1P01-32] Poster session

[1P26] Effect of plasma-facing materials on ammonia formation in H₂/N₂ plasmas: A residual gas analysis

*Takuma Okamoto¹, Naomichi Ezumi¹, Enji Kinbara¹, Kota Saito¹, Dogyun Hwangbo¹, Satoshi Takahashi¹, Satoshi Togo¹, Mizuki Sakamoto¹, Haruhiko Himura¹ (1. University of Tsukuba (Japan))

Plasma detachment, achieved through enhanced plasma-neutral interactions, is a promising approach for reducing the heat flux on divertor targets. In H₂/N₂ detached plasmas, NH_x species promote volumetric recombination and are also key intermediates. Previous studies have suggested that plasma-assisted ammonia synthesis proceeds on metal surfaces. In this study, ammonia formation on different plasma-facing materials is experimentally investigated. W and SiO₂ samples are exposed to H₂/N₂ plasmas, and residual ammonia is evaluated from the m/z = 17 signal measured by a quadrupole mass spectrometer after plasma discharge. Both the peak and integrated ammonia signals are higher for the W sample than for the SiO₂ sample. Although the ammonia signal from the SiO₂ sample increases with repeated plasma shots, the W sample consistently exhibits a higher ammonia signal. These results suggest that the surface condition of the W sample may enhance ammonia formation under divertor-simulated plasma conditions, although the effects of the material itself and its prior plasma-exposure history cannot yet be distinguished.

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