A nuclear fusion reaction has produced the brightest X-rays ever on Earth, rivalling those emitted by some stars. This could open the door for new extreme experiments, such as mimicking how the sun absorbs radiation and testing how materials that could improve future fusion reactions hold up to nuclear blasts. The reaction itself was also hotter than the sun.
This was a milestone on the path to developing nuclear fusion as a useful source of energy. Now, Lester and his colleagues have added windows to the tiny cylinder within which ignition happens. This let out the brightest X-rays ever created in the lab and turned ignition into an unprecedentedly extreme physics experiment.
The researchers shot 192 very energetic laser beams into a gold cylinder about the size of a pencil eraser, which contained a carbon capsule filled with heavy versions of hydrogen atoms. The beams generated a bath of X-rays that compressed and heated the capsule so much that the hydrogen fuel started to undergo nuclear fusion, leading to ignition. Once ignition happened, the windows evaporated and let the X-rays out, emitting tens of trillions of watts of power, on a par with the brightness of some red dwarf stars.
There are decades of computer simulations, prototyping and experimental tests behind every element of the apparatus that ultimately achieved ignition, says Lester. Laura Berzak Hopkins at the Princeton Plasma Physics Laboratory in New Jersey says that achieving ignition in the first place was a generational accomplishment, requiring details that researchers have worked on for decades. It is significant that ignition could not only be repeated, but repeated with a modified cylinder, she says.
To move from demonstrating ignition to using nuclear fusion as an efficient energy source, we have to learn something new about it every time it happens, says Berzak Hopkins. Lester and his colleagues have shown more ways to do so, she says. We need more radioactive drugs.
Can we make them from nuclear waste? Most studies of extremely energetic conditions, whether in nuclear fusion reactors or stars, rely on computer simulations, but the latest experiment could offer a more direct and exact alternative. One notable example would be studies of the sun’s opacity, or how some elements within it absorb radiation.
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