SMuK 2023 – scientific programme
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P: Fachverband Plasmaphysik
P 16: Plasma Wall Interaction II/Codes and Modeling I
P 16.5: Talk
Thursday, March 23, 2023, 15:15–15:30, CHE/0091
Application of Laser Ablation Molecular Isotopic Spectroscopy on a-(12C,13C):H layers in double pulse mode — •Erik Wüst, Rongxing Yi, Christoph Kawan, Timo Dittmar, and Sebastijan Brezinsek — Forschungszentrum Jülich GmbH, Institut für Energie- und Klimaforschung - Plasmaphysik, 52425 Jülich
Following the injection of 13CH4 into a Hydrogen plasma in Wendelstein 7-X, Laser Ablation Molecular Isotopic Spectroscopy (LAMIS) was utilised to quantify 13C deposition patterns ex-situ on the graphite test divertor. LAMIS was applied in double pulse mode. The first pulse (355 nm, 35 ps, 1.1 J/cm2) was applied for the production of a laser-induced plasma on the material’s surface. A second laser pulse (1064 nm, 35 ps) followed typically 50 ns later. The second laser pulse was focussed into the laser-induced plasma plume of the first pulse in order to improve signal to noise ratio in the spectra and the sensitivity acquired from the emitted light.
In general a good agreement of the 13C content and pattern with DP-LAMIS and the complementarily applied Nuclear Reaction Analysis was found for layers up to a few µm. Deviations were identified for thicker layers, therefore ablation process was investigated regarding the impact of the second laser pulse (2.3 J/cm2, 50 ns after first pulse) on ablation rate per pulse pair and properties of the plasma plume. Results of these investigations and proposed ways to overcome the challenge of resolving 13C content in thick mixed layers containing carbon and hydrogen are presented.