A reactor in southern France has generated and sustained a 50-million-degree Celsius plasma for a record-breaking six minutes, a significant step towards making fusion energy a reality.
On May 6, scientists at the Princeton Plasma Physics Laboratory (PPPL) in New Jersey announced that the device held the superheated matter known as plasma at 50 million degrees Celsius for six minutes straight, according to Business Insider. The ultimate goal is to sustain a superheated plasma for hours, but six minutes is still a new world record for a device like WEST. Other nuclear fusion reactors have produced hotter plasma, but not for as long.
WEST is a tokamak, a room-sized, doughnut-shaped fusion reactor measuring 8 feet by 8 feet by 8 feet that generates the same type of energy as the sun. That's why scientists refer to these devices as "artificial suns."
"What we are trying to do is recreate the sun on Earth," said Luis Delgado-Aparicio, PPPL's senior project manager. "That's an enormous challenge," but the new record shows that they are on the right track.
Inside the WEST Reactor
The sun is powered by fusion (where atomic nuclei combine and release energy), unlike the fission (where atomic nuclei are split and release energy) that powers today's nuclear power plants. Fusion energy is more powerful than any form we have today. If harnessed, fusion could produce nearly 4 million times more energy per kilogram of fuel than fossil fuels and is carbon-free.
While WEST is not meant to produce fusion electricity for homes, the test reactor is laying the groundwork for future commercial reactors. WEST shares many features with ITER, a reactor under construction in southern France that will be the world's largest tokamak and can sustain a burning plasma when it's completed. Creating such a self-heating mixture of hydrogen isotopes is the key to unlocking the commercial potential of fusion. However, due to cost and engineering challenges, it's unclear when ITER will be finished. In the meantime, other facilities, including WEST, are experimenting to figure out the best way to operate the massive reactor. ITER and WEST are located relatively close together, and experiments on WEST can be directly applied to ITER, according to Delgado-Aparicio.
To achieve fusion on Earth, the fuel must reach temperatures of at least 50 million degrees Celsius. One of the major challenges facing fusion reactors is the immense amount of energy required to generate such extreme heat. Until now, reactors have not been able to sustain a plasma long enough to reach "breakeven," where a fusion reactor produces as much energy as it consumes. The WEST breakthrough is no exception. However, the facility generated more energy from fusion than in previous runs by 15 percent, and the plasma was also twice as dense.
WEST is also helping scientists test the best materials to build the walls of a fusion reactor, as the environment inside can be hotter than the core of the sun by a factor of three. WEST originally had carbon walls. While carbon is relatively easy to work with, it also absorbs tritium, a rare isotope of hydrogen that is a fuel for fusion.
Therefore, in 2012, scientists decided to experiment with a different material for the walls of the tokamak: tungsten. It is also the material that ITER will use for some of its key components. Because tungsten can withstand heat without absorbing tritium, Delgado-Aparicio believes it is the ideal material for the lining of a tokamak reactor. Tungsten is not without its drawbacks, however, such as its potential to melt and contaminate the plasma. The WEST experiments are helping the team understand exactly how tungsten behaves and interacts with the plasma so that the system can be optimized.
The researchers at PPPL are adapting a diagnostic tool for use in the newest experiments on WEST. This tool will allow them to measure the temperature of the plasma with more precision, giving them a better understanding of how tungsten moves from the walls of the device into the plasma. PPPL expects to publish the results of the experiments in a peer-reviewed journal in the coming weeks.
Summary
Scientists in France have achieved a new milestone in the pursuit of fusion energy. The WEST reactor sustained a superheated plasma at 50 million degrees Celsius for six minutes, the longest duration ever achieved by a device of its kind. This breakthrough is a significant step towards making fusion energy a reality, which could provide a virtually limitless, carbon-free source of power.