The energy of a star in a sphere one meter in diameter. Something similar to this is what an international team of physicists who are developing a nuclear fusion minireactor have proposed.
100 million degrees. A group of researchers has managed to exceed 100 million degrees inside ST40, a tokamak nuclear fusion reactor. The ST40 is a compact spherical reactor, its diameter covers only about 80 centimeters.
Behind the achievement are researchers from the British company Tokamak Energy Ltd, the Princeton Plasma Physics Laboratory, the Oak Ridge National Laboratory, and the Jülich Research Center in Germany.
Apple shape. In addition to its size, the ST40 differs from other tokamaks (Russian acronym for toroidal chamber reactors with magnetic coils) in its shape.
While the toroid of reactors such as the ITER (International Thermonuclear Experimental Reactor) is conventional, that is, it has the shape of a “donut”, the section of the chamber that contains the plasma in the ST40 has a “D” shape, which when rotated around the central axis gives the reactor a shape close to the sphere, like an apple with its core as the axis.
The energy of the Sun. Nuclear reactors are one of the great bets that humanity has to achieve clean, abundant and cheap energy. Its operation at the atomic level is similar to that which makes stars expel energy: the fusion of two light isotopes (deuterium and tritium) into a heavier atom (Helium).
The difference is that, whereas in stars it is gravity that causes the force that repels individual atoms to be overcome and the atoms to fuse together; In a tokamak reactor this is achieved by first confining the hydrogen isotopes in the chamber via magnetic fields to give them sufficient density, and then heating them to a sufficient temperature to create a plasma that overcomes this repulsion.
The barrier of 100 million degrees K (an energy equivalent of 8.6 kiloelectronvolts) is key when it comes to achieving the goal of fusion of atoms. To achieve this, those responsible for the experiment concentrated the thermal energy in a short period of time. In addition, they used the “trick” of heating positively charged ions more than those, the “hot ion mode”, a mechanism that helps increase reactivity and improves the operation of the tokamak.
Many roads, one direction. Fusion power is still some way off. As in cases such as the US National Ignition Facility (NIF) experiment, scaling this process will be one of the great challenges. To this we must add the advantage of the NIF experiment that at the end of last year managed to overcome the ignition barrier (expel more energy than introduced).
The technology used by the ST40 is similar to that which serves as the basis for the SMART Tokamak (SMall Aspect Ratio Tokamak). This reactor was presented by the University of Seville as the Spanish bet to break the record of 100 million degrees. Although it is late for the record, there is still a lot that this design could contribute.
For now, ITER continues to be one of the great international assets to advance towards fusion energy. The scale of ITER is much higher than that of SMART and ST40, but the experiment continues to advance. The race towards fusion is uncertain (perhaps we will never reach it) but of course there is no shortage of participants in this collective effort.
In Xataka | ITER’s best ally is in Japan and it is essential for nuclear fusion to be possible
Image | Tokamak Energy
