Posted on: 15th October 2015

When experiments are running at ASDEX Upgrade, the medium-sized tokamak housed at the Max-Planck institute for Plasma Physics (IPP), Garching, Germany, you can find Matthias Willensdorfer in the control room. Sitting between 30 other scientists, he operates diagnostics that measure electron temperatures inside the tokamak, and his task is to ensure that the data collected is correct.
Whenever there is a failure in the complex setup of his diagnostic, Matthias has to rush to identify the source of the error and resolve it. It could be a power supply breaking down in one of the components or a device deep in the signal chain is not working correctly. And, he has all of twenty minutes to do this before the next cycle of the experiment starts again. “It can be exciting…and stressful,” he says with a smile.

Matthias joined IPP as a EUROfusion fellow after completing his PhD at the Vienna University of Technology and working as a guest scientist at ASDEX Upgrade. He says that running experiments in ASDEX Upgrade is just one facet of his job. “You can spend anything from months to a few years developing and building new diagnostics or planning new experiments to test theories or hypotheses,” Matthias explains. Experimental work and the anticipation of the experimental results make fusion research exciting for him. “Fusion science combines several fields such as fluid-dynamics, electrodynamics and plasma physics… it never gets boring,” he points out.

By delving into physics, data analysis, and programming, what Matthias is trying to do is to study the response of the plasma on external magnetic perturbations produced by additional coils. Fusion plasmas can develop various kinds of instabilities. And, some of them such as the Edge Localised Modes (ELMs) have the potential to damage the inner lining of the wall of a tokamak, for example. “External magnetic perturbations, though small, can be used to mitigate such ELMs,” explains Matthias. “In theory, the plasma can weaken or amplify these perturbations and therefore can change the behaviour of these edge instabilities. My task is to measure and characterize this response and compare it with different theories.”

The physics, the experiments, data analysis and programming aside, Matthias says that there was also some idealism behind his decision to pursue fusion research. “The energy problem is huge, and I want to do something about it.” And fusion research it was.