Greifswald 2024 – scientific programme

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P: Fachverband Plasmaphysik

P 3: Plasma Wall Interaction I

P 3.2: Talk

Monday, February 26, 2024, 14:30–14:45, ELP 6: HS 3

Characterization of boron layers on tungsten substrates by picosecond and nanosecond laser-induced breakdown spectroscopy — •Huace Wu, Sebastijan Brezinsek, Rongxing Yi, Anne Houben, Gennady Sergienko, and Yunfeng Liang — Forschungszentrum Jülich GmbH, Institut für Energie- und Klimaforschung * Plasmaphysik, Partner of the Trilateral Euregio Cluster (TEC), 52425 Jülich, Germany

Boronization is considered in ITER as wall conditioning method for full-W material option. Boron acts primarily as oxygen getter, but can also reduce intrinsic impurity content such as carbon and nitrogen as well as moderately the hydrogen recycling. However, the boron layer thickness, and therefore the lifetime by plasma-induced erosion, is limited, not necessarily toroidal homogeneous, and repetitively boronization needs to be applied to be effective. LIBS as a versatile tool for the investigation of the element composition and is a potential candidate for in-situ investigations of erosion, deposition and material mixing in nuclear fusion devices. At first, we study LIBS in the laboratory on thin boron films (about 100nm) or boron-tungsten layer systems produced by magnetron sputtering on the polished tungsten substrates. Ps (35ps,355nm) and ns (7ns,1064nm) lasers were used to characterize the ablation rate of boron layers as well as matrix effects in the layer system. The ps laser provides a better depth resolution due to the smaller ablation rate. Comparison studies with boron layers (about 10nm) obtained on W substrates in the midplane manipulator of W7-X from boronization will be presented.

Keywords: Plasma-Wall Interaction; Laser-induced Breakdown Spectroscopy; Boronization; Laser ablation rate