Researchers Test Next Stage of Record-Breaking Fusion Experiment JET

Forschungszentrum Juelich

Jülich, September 26, 2022 – In spring 2022, European and Jülich researchers achieved a new fusion energy record with the JET fusion experiment. Now EUROfusion experts want to use the facility in Abingdon near Oxford, England, to prepare for the first phase of the ITER fusion megaproject currently under construction in southern France. The experiments in JET are intended to provide information about the behaviour of helium plasmas. Corresponding wall elements for JET have been studied for preparation at the PSI-2 linear plasma facility at Forschungszentrum Jülich.

Forschende testen in Jülich die nächste Stufe des Rekord-Fusionsexperiments JET
View into the JET fusion experiment
Copyright:
– UKAEA

Fusion energy is based on the same processes that power the sun and stars. The record JET project results announced in February, which released 59 megajoules of energy, were the world’s clearest demonstration of the potential and another step toward a secure and sustainable energy supply.

Forschende testen die nächste Stufe des Rekord-Fusionsexperiments JET
Scientists in the control room of the JET experiment
Copyright:
– UKAEA

The construction of the ITER international fusion reactor is considered the next major goal in fusion research. The facility is scheduled to begin operation in 2025 and will demonstrate the generation of thermal energy for the first time. ITER will initially run on helium plasmas, instead of the high-energy fuels deuterium and tritium used by JET at the record in late 2021.

In order to reach full power more quickly later with ITER, EUROfusion researchers will study the behaviour of the helium plasmas and test the effects of helium on JET’s tungsten and beryllium walls.

“In preparation, we exposed tungsten-coated JET wall elements to helium plasmas in the Jülich linear plasma facility PSI-2 to determine the optimal conditions for the upcoming JET experiments,” says Dr. Timo Dittmar of Forschungszentrum Jülich, referring to Jülich’s significant contribution to the upcoming experiments. “An important aspect of this was the verification of the temperature window in which tungsten fuzz, a fractal, grass-like surface structure, is formed by bombardment with helium ions. This opportunity allowed us to simultaneously test diagnostic methods and algorithms in spectroscopy and infrared observation in advance on real JET samples.”

After the experiments of the upcoming helium campaign, the scientists of Forschungszentrum Jülich will accompany the evaluation of the experiments by simulations. The corresponding simulation codes were developed at Jülich and are now used worldwide.

Forschende testen in Jülich die nächste Stufe des Rekord-Fusionsexperiments JET
Scanning electron image of an untreated surface of a tungsten-coated JET sample (left) and the Fuzz-like surface structure (right) on the sample surface after exposure to a helium plasma in the Jülich linear plasma facility PSI-2.
Copyright:
– Forschungszentrum Jülich

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