Scientists are working on a type fusion reactor called the stellarator to harness the power of nuclear Fusion.
A new paper claims that the Wendelstein 7X stargazer in Germany can now contain heat up to twice the temperature of the Sun's core. This is a significant step in the development of stellarator technology.
Novimir Pablant, Princeton Plasma Physics Laboratory (PPPL), said that "It's really exciting for fusion that this design was successful." It clearly shows that optimization is possible.
The focus of energy development efforts worldwide is on fusion power. It works by harnessing the energy produced when plasma nuclei fuse to create a heavier element. This is the same process as in the heart of stars. This would result in huge, clean, high-output, energy that is practically unstoppable.
It's not an easy task, but it is possible. It is a very energetic process and it can be difficult to contain. Although fusion energy was discovered for the first time in the 1940s, decades later, reactors that use fusion energy still produce less energy than they lose. However, the gap is narrowing.
Tokamak, a loop of plasma in the shape of a doughnut that is trapped in a magnetic field shell and driven at high speed with short pulses, is currently the fusion technology breaking all temperature records. Its relative simplicity allows it to be contained at high temperatures but only in short bursts.
Stellarators are made up of a complex combination of magnets that an AI maps out to control plasma flow. These stellarators are difficult to design and construct, which has led to stellarators that lose a lot of the energy from fusion.
Wendelstein 7-X. (Bernhard Ludewig/Max Planck Institute of Plasma Physics).
This heat loss is caused by a process known as neoclassical transportation, where colliding ions from a fusion reactor cause plasma to diffuse outwards. It is more effective in stellarators than it is in tokamaks.
Tokamaks are inefficient, so researchers from PPPL and Max Planck Institute for Plasma Physics tried to modify the magnets in W7X to reduce the effects of neoclassical transportation. Now, measurements using an instrument called the X-ray imaging cristal spectrometer (XICS) have revealed very high temperatures within the reactor.
These measurements are supported by the charge exchange recombination spectroscopy measurements (CXRS), which are more precise than the XICS but cannot be taken under all circumstances.
Both data sets agree that the stellarator was capable of reaching temperatures close to 30 million Kelvin.
The team concluded that this would be possible only if there was a sharp decrease in neoclassical transportation. The team did modeling to calculate how much heat would be lost by neoclassical transportation if W7X was not optimized. They found that the range of 30 million Kelvin was far too high.
Pablant stated that this showed W7XX's optimized shape reduced neoclassical transport. This was essential for the W7X experiment performance. It was a way to show how important optimization was.
This amazing result is a significant step forward in refining the stellarator design and will help shape future efforts.
This is a major step towards a practical, fusion reactor. However, there are still many things to do. A fusion reactor must not only have high temperatures but also have the right amount of plasma density and adequate confinement times to make it practical. Tokamaks are hotter but stellarator technology can still have an advantage by reducing energy loss.
Pablant stated that "Reducing neoclassical transportation is not the only thing you need to do." There are many other goals to achieve, such as running stable and reducing turbulent transport.
There are many nuclear fusion reactor technologies in development. It seems like it will only take a few years before one of them comes to fruition. Although it may be some time before energy from fusion is available for our power grids it could very well make a significant impact on the world.
W7-X is currently being upgraded and will recommence operation in 2022.
Nature published the research.
