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Fusenet enabled me to go abroad during my graduation project. For six months I was able to work at the Max Planck Institut für Plasmaphysik in Greifswald. This institute has the most advanced stellarator in the world called Wendelstein 7-X. My project involved investigating neutral beam attenuation of the newly implemented neutral beam source. This was done by using the ITER-Like Spectrometer and an application of it called beam emission spectroscopy.

Beam emission spectroscopy makes it possible to visualize how the beam density drops as the beam penetrates the plasma. A forward-fitting model has been written to determine the intensity of the beam emission and separate it from the rest of the spectrum. This intensity scales with the beam density and some other plasma parameters. By using multiple viewpoints, a radial profile can be made of the neutral beam density. How the beam density changes in the plasma is an indication of how the neutral beam fuels the plasma. This is the first step in determining how the NBI fuels the plasma. The eventual goal would be to investigate if the neutral beam can help with fuelling the core of the plasma and the research undertaken is the first step to finding this out.

My period in Greifswald included time before during and after the 2018 W7-X campaign. It was interesting to see the progress that can be made on the experimental side within a relatively short amount of time. The people I’ve worked with were all very friendly and helpful and I enjoyed my time spent in Greifswald both during and after work hours.

- Tristan Neelis