Testing of the Wendelstein 7-x stellarator has started with a bang, albeit a very very small one, with researchers switching on the experimental fusion reactor to produce its first helium plasma at the Max Planck Institute for Plasma Physics (IPP) in Greifswald, Germany. After almost a decade of construction work and more than a million assembly hours, the first tests have gone according to plan with the researchers to shift focus to producing hydrogen plasma after the new year.

Assembly of the Wendelstein 7-x stellarator was completed in April of last year, and after a period of careful testing of its various components, the science team finally flicked the switch on December 10. This saw around a single milligram of helium gas heated to one million degrees Celsius (1.8 million° F), with the flash observed on cameras and measuring devices for one tenth of a second.

"We're very satisfied", said Dr. Hans-Stephan Bosch, division head of Wendelstein 7-X, following the December 10 test. "Everything went according to plan."

As part of the ongoing pursuit of a clean and reliable power source, the Wendelstein 7-x is the largest stellarator fusion device in the world and represents a different approach to typical doughnut-shaped tokamak fusion reactors. Scientists hope that the stellarator design can overcome one of the main limitations of the tokamak, where the plasma contained in the vessel is prone to drifting into the outer walls and collapsing after operating only in short bursts.

The designers of the Wendelstein 7-x are of the view that the device will offer the required stability for continuous nuclear fusion power generation. It uses a cage of 50 superconducting coils to suspend super-hot plasma in the center of a twisting magnetic field for more than 30 minutes at a time.

From its first successful tests, the team will now aim to prolong the duration of the plasma discharges and explore the best means of producing and heating helium plasma using microwaves. In January, the team will then turn its attention to producing the first plasma from hydrogen.

You can see the fleeting flash of helium plasma and the reactions of control team in the video below.

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