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10 - From experimental devices to a reactor  

For a long time the Fusion community has attempted to define what the future current generating fusion reactor might be like. We thus have regularly updated studies, which set out the outlines and sometimes the details of what a fusion reactor could be. In addition to these forecasts, we should mention the detailed engineering studies performed in the ITER project, which, although not totally representative, have, all the same, precisely defined most of the main components of the reactor. The diagram of the principle of the electro-generating reactor is shown below.

The deuterium-tritium fuel mixture is injected (1) into a chamber, where, thanks to a system of confinement it goes into a plasma state and burns (2). In doing so, the reactor produces ash (helium atoms) and energy in the form of fast particles or radiance (3). The energy produced in the form of charged particles and radiance, is absorbed in a special component, the "first wall" which, as its name illustrates, is the first material element encountered by the plasma. The energy, which appears in the form of kinetic energy in neutrons, is, for its part, converted into heat in the breeding blanket (4) : which is the element beyond the first wall, but nevertheless inside the vacuum chamber. The vacuum chamber itself is the component enclosing the area where the fusion reaction takes place. The first wall, blanket and vacuum chamber are obviously cooled down by a heat extraction system. The heat is used to produce steam and supply a conventional turbine and alternator electricity producing system (5).

If we exclude all the components dealing with energy production (breeding blanket for example), a reactor will look much like what an experimental installation of the next generation like ITER will be. This future installation will validate feasibility of energy production through thermonuclear fusion not only as regards physical principles but also as regards most of the main components within a reactor (huge superconducting magnetic coils for example). Performance in terms of plasma confinement required from an electricity generating reactor are only 4 or 5 times higher than the nominal performance of the ITER project. We can reasonably guess that the first electric kW produced by a thermonuclear fusion reactor prototype may see the light of day around 2050 that is to say about a hundred years after the initial research on controlled thermonuclear fusion. A period of a hundred years between the discovery of the concept and final use is not as unusual as that. After all, the discovery of the principle of solar cells goes back to 1839 (A. Becquerel) and the discovery of the principle of the fuel cell goes back to 1839 (W.R. Grove).

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