It would provide humankind with near limitless energy, ending dependence on fossil fuels for generating electricity.
US Government physicists have backed plans to create ‘a star in a jar’ – replicating on Earth the way the sun and stars create energy through fusion.
Physicists at the U.S. Department of Energy’s Princeton Plasma Physics Laboratory (PPPL) revealed their plan for a next generation fusion device in a paper published in the journal Nuclear Fusion.
‘We are opening up new options for future plants,’ said lead author Jonathan Menard, program director for the recently completed National Spherical Torus Experiment-Upgrade (NSTX-U) at PPPL.
The $94-million upgrade of the NSTX, financed by the U.S. Department of Energy’s Office of Science, began operating last year.
Spherical tokamaks are compact devices that are shaped like cored apples, compared with the bulkier doughnut-like shape of conventional tokamaks.
The plants already exists in experimental form – the compact spherical tokamaks at PPPL and Culham, England.
These tokamaks, or fusion reactors, could provide the design for possible next steps in fusion energy – a Fusion Nuclear Science Facility (FNSF) that would develop reactor components and also produce electricity as a pilot plant for a commercial fusion power station.
The increased power of the upgraded PPPL machine and the soon-to-be completed MAST Upgrade device moves them closer to commercial fusion plants, the researchers say.
The NSTX-U and MAST facilities ‘will push the physics frontier, expand our knowledge of high temperature plasmas, and, if successful, lay the scientific foundation for fusion development paths based on more compact designs,’ said PPPL Director Stewart Prager.
However, the devices face a number of physics challenges.
For example, they must control the turbulence that arises when superhot plasma particles are subjected to powerful electromagnetic fields.
They must also carefully control how the plasma particles interact with the surrounding walls to avoid possible disruptions that can halt fusion reactions if the plasma becomes too dense or impure.
Researchers at PPPL, Culham, and elsewhere are looking at ways of solving these challenges for the next generation of fusion devices.
The spherical design produces high-pressure plasmas – the superhot charged gas also known as the fourth state of matter that fuels fusion reactions – with relatively low and inexpensive magnetic fields.
This unique capability points the way to a possible next generation of fusion experiments to complement ITER, the international tokamak that 35 nations including the United States are building in France to demonstrate the feasibility of fusion power.
ITER is a doughnut-shaped tokamak that will be largest in the world when completed within the next decade.
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