The Princeton Plasma Physics Laboratory (PPPL) hits a new fusion reactor endurance record that could open the door to practical fusion power on a commercial scale. Using a tungsten lining, the WEST reactor held a reaction for six minutes.
Fusion reactions may power the Sun and make life on Earth possible, but duplicating that process on this planet is currently stuck at two ends of an extreme. On the one hand, fusion can be set off instantly in the heart of a hydrogen bomb with enough energy released to blast a city off the map. At the other, fusion can be induced on a lab-bench level at such low energy returns that such a setup was showcased at the General Electric pavilion at the 1964 New York World’s Fair, where it regularly fused atoms together for the public.
The hard part is getting these two extremes to meet somewhere in the middle. No, that’s not right. The hard part is to get them to meet in the form of a reactor that can generate more energy than it takes in on a sustained, practical, commercial scale.
To do this, the reactor doesn’t just need to achieve fusion or do so for an extended period. It needs to be able to do so on a large enough scale using a machine that can stand up to all of the stresses of recreating the conditions in the heart of the Sun.
According to the US Department of Energy’s PPPL, the recent record set by the W (the chemical symbol for tungsten) Environment in Steady-state Tokamak (WEST) of sustaining a reaction for six minutes after an injection of 1.15 gigajoules of power steady-state central electron temperature of 4 keV isn’t an absolute record. There are other tokamaks that have done better, WEST scores in the practicality stakes.
Located at the nuclear research center of Cadarache, Bouches-du-Rhône in Provence, France, WEST is a reconfigured version of the Tore Supra tokamak. During the six-minute run, the plasma suspended inside the reactor’s super-powerful magnetic fields reached a temperature of 50 million ºC (90 million ºF) and achieved 15% more energy with twice the plasma density.
But the real showstopper was that this was done with a tokamak chamber lined with tungsten. Earlier versions used a graphite lining, which achieved better performance. But graphite tends to absorb the fuel into itself, which is undesirable in a commercial reactor. Tungsten has a much lower rate of this, making it more practical and desirable. However, tungsten atoms can also get into the plasma, rapidly cooling it.
PPPL says that WEST is very far from a practical reactor, but it is a major step as the laboratory works on how to tweak the tungsten.
“The tungsten-wall environment is far more challenging than using carbon,” said Delgado-Aparicio, PPPL’s head of advanced projects and lead scientist for the physics research and the X-ray detector project. “This is, simply, the difference between trying to grab your kitten at home versus trying to pet the wildest lion.”
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