A nuclear fusion reactor has reached temperatures twice that of the sun

This is the result achieved by the Wendelstein 7-X stellarator in Germany. A useful milestone towards the creation of new power plants

The Wendelstein 7-X stellarator at IPP Greifswald - Max Planck Institute for Plasma Physics (photo IPP, Volker Steger) A new success for the nuclear physics and a step towards working nuclear fusion reactors. Today a particular reactor, the Wendelstein 7-X (W7-X) stellarator in Germany, has reached temperatures double those of the Sun's core.

Used since the 1950s, stellarators aim to reproduce the nuclear fusion, or the same processes that take place inside the stars (hence the name, which comes from the crasis of the term stellar generator). The Wendelstein 7-X prototype, recently developed by the Max Planck Institute of Plasma Physics (Ipp), is the most advanced in the world and today the physicists of the Princeton Plasma Physics Laboratory (Pppl), who work on it, confirm its power. The results are published in Nature.

A unique stellarator

Used since the 1950s, stellarators use powerful magnetic fields to confine the plasma - ionized gas, the matter at the base and which it will give rise to the nuclear reaction - inside the reactor, of this big donut. Twenty years later, in the seventies, these instruments were largely supplanted by the so-called tokamaks, reactors similar in characteristics, but with superior performance, albeit with some limitations.

Completed in 2015, Wendelstein 7-X is the largest stellarator in existence and intends to overcome some limitations of its predecessors. In general, the goal is to study and succeed in obtaining the continuous production of electricity, remembering that to date it is not possible to have this result with the reactors available (there are no reactors of this type and the goal is set in 2050). The German stellarator is able to achieve this performance for 30 consecutive minutes.

Today's result

One of the main problems, particularly concerning stellarators (more than tokamaks), it is the loss of heat and energy due to a process called neoclassical transport, in fact collisions that cause heated particles to come out of orbit, out of confinement. In the study, the authors demonstrate that the particular design of the stellarator's intertwined complex magnets reduce this problem by limiting energy loss.

The proof comes thanks to the particular X-ray spectrometer, called Xics, which measured the high temperatures reached inside the reactor. These temperatures, the authors explain, would not have been achieved without decreasing heat loss. The measurement, therefore, is proof of the stellarator's good performance and the Xics tool was central to having it. “Without Xics - explains Robert Wolf, co-author of the research - we probably wouldn't have discovered this good confinement regime.”

But that's not all: there are still many steps to take to further improve the capabilities of the stellarator. After a 3-year hiatus for reactor upgrades, W7-X will return to operation in 2022. The changes involved building a cooling system to prolong nuclear fusion experiments and a divertor to further reduce losses. This will lead to the new investigation step: to understand if the stellarator can represent a prototype for the creation of new power generation plants.

Nuclear fusion

Nuclear fusion is a reaction in which the nuclei of two or more atoms come together - fuse - to form the nucleus of another heavier chemical element. It is a process underlying the functioning of the stars, for example of our Sun: the Sun is like a large nuclear fusion reactor in which the fusion of 4 hydrogen nuclei (i.e. 4 protons) continuously takes place in a helium nucleus, a continuous atomic explosion that produces and floods us with energy. To observe this reaction the nuclei must be very close and a great deal of energy is required to overcome the electromagnetic repulsion (so proton and proton repel each other).


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Topics

nuclear energy Physics nuclear fusion globalData.fldTopic = "nuclear energy, Physics, fusion nuclear "

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