Chinesisch-Deutsches DFG-Forschungsprojekt „Diagnostik der Plasma-Wand-Wechselwirkung von Fusionsplasmen“ (HHU Düsseldorf / FZ Jülich / ASIPP Hefei / DUT Dalian)

Controlling the plasma-wall interactions is mandatory to guarantee the lifetime and efficiency of future fusion devices like ITER and the Chinese project CFETR. In current facilities like EAST (Hefei, China)  and W7-X (Greifswald, Germany) wall material is taken out after plasma operation and is then  analysed for hydrogen and deuterium loading. In many cases, these loadings shall be detected “in-situ”, i.e. during plasma-operation. This can be done by the so called “Laser Induced Breakdown Spectroscopy” (LIBS) which provides insight into the composition of the loaded material by analysing the spectra emitted by a laser induced plasma on the wall-surface.

In our cooperation LIBS is used with different laser systems at fusion-wall material loaded with deuterium. The laser systems differ in pulse duration and peak-intensity. With our studies we want to be able to describe the ablation process with our femtosecond laser in more detail and show the advantages over nanosecond- or picosecond- laser systems. First experiments have shown that well-defined craters are produced which enables quantitative measurements of the loaded material in different depths. In the course of the project, we will also investigate the basic mechanisms concerning the transfer of laser energy into solid matter. This is a succession of ultrashort processes which we will try to observe and simulate.

The project is funded by the German Research Foundation (DFG) and the National Natural Science Fondation of China (NSFC). Our project partners are the IEK-4 at Forschungszentrum Jülich , the Institute of Plasma Physics (ASIPP) in Hefei and the Dalian University of Technology (DUT). The project kick-off took place during the 5th SINO-German Workshop on Plasma-Wall Interactions in Fusion Devices in March 2019. In August 2019 a scholarly exchange brought first results from the nanosecond laser system at Dalian.