Experimentation with Germany's newest fusion reactor is beginning to heat up, to temperatures of around 80 million degrees Celsius, to be precise. Having fired up the Wendelstein 7-X to produce helium plasma late last year, researchers have built on their early success to generate its first hydrogen plasma, an event they say begins the true scientific operation of the world's largest fusion stellarator.
After a decade of construction, the Wendelstein 7-X fusion stellarator was finally started up in December last year. The device is designed to be magnetically efficient enough to continuously contain super-hot plasma in its magnetic field for more than 30 minutes at a time. If this vision does one day become a reality, it could help to usher in an era of clean, reliable nuclear fusion power.
But it's all about baby steps for scientists working at the Max Planck Institute for Plasma Physics (IPP), which houses the experimental device. Since producing the first helium plasma on December 10 last year, the Wendelstein 7-X has generated more than 300 discharges. The main purpose of these was to clean the plasma vessel walls, which in turn makes for higher temperatures, but it also allowed for testing of scientific instruments and data recording.
"This makes everything ready for the next step," says project boss Professor Dr. Thomas Klinger. "We are changing from helium to hydrogen plasmas, our proper subject of investigation."
At a ceremony on Wednesday, quantum physicist (who also happens to be Germany's Federal Chancellor) Angela Merkel spoke for around 20 minutes, before pressing the button to initiate the test. This saw a 2-megawatt pulse of microwave heating convert a small amount of hydrogen gas into a low-density hydrogen plasma.
"With a temperature of 80 million degrees and a lifetime of a quarter of a second, the device's first hydrogen plasma has completely lived up to our expectations,," says IPP's Dr. Hans-Stephan Bosch.
The researchers will continue in this experimentation phase until mid-March. They will then open up the plasma vessel and install carbon tiles for better protection, along with a device designed to remove impurities. These enhancements will make for even higher temperatures and longer discharges lasting up to 10 seconds. They plan on making similar improvements over the next four years until Wendelstein 7-X can produce discharges lasting 30 minutes at a full heating power of 20 megawatts.
At a cost of more than €1 billion ($US 1.1 billion) and one million man-hours, Wendelstein 7-X will never generate a single watt-hour of energy. Rather it is intended to establish the potential of stellarators as power plants by demonstrating their main advantage over tokamak fusion reactors, which is the ability to operate continuously rather than only in short bursts.
The video below shows the ceremony in its entirety (you can skip to 41 minutes to see Merkel press the magic button).
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