For the last 60 years, fusion power plants have always been 20 years away, but breakthroughs in the last 12 months might turn the optimistic prediction into a realistic schedule.
In a paper, published in the journal Nuclear Fusion, a British-American team has produced an in-depth technical summary for an all-new spherical fusion reactor. The team analyzed what makes the spherical reactor a good pilot project for the fusion power plant of the future.
Currently, the most advanced spherical tokamaks – the technical name for the reactor – are the recently completed National Spherical Torus Experiment Upgrade (NSTX-U) at Princeton Plasma Physics Laboratory and the MAST facility at Culham in the UK.
While we have been able to create controlled fusion reactions since the late 1950s, we have yet to make fusion reactors energetically viable. Nuclear fusion is the reason why stars shine, and obtaining the conditions at the core of the Sun is very difficult. So far, every reactor requires more energy to start than we can get out. Scientists all over the world are attempting to put a star in a jar, and while the science is the same, the shape of the jar is very different.
The most common reactor is a donut-shaped tokamak, which allows for a (relatively) easy approach to the confinement of the plasma. Alternatives to this are the stellarator and the spherical tokamak, which looks more like a cored apple.
"The main reason we research spherical tokamaks is to find a way to produce fusion at much less cost than conventional tokamaks require," said Ian Chapman, leader of the UK's magnetic confinement fusion research program at the Culham Science Centre, in a statement.
The spherical tokamak is also more compact, and a diminutive size not only makes it more versatile, it also reduces construction costs or at least allows for the use of the latest materials, making it more reliable.
The NSTX-U is going to have twice the power and five times the pulse length of its predecessor, and it will test if the geometry and material used can withstand the extreme conditions produced by the hot plasma.
The study describes in detail the potential of this spherical configuration and it’s not up to the devices to deliver these high-performance scenarios.