The ITER site, the experimental nuclear fusion reactor under construction in the south of France, has just taken a real step forward with the reception of a huge support structure which will soon host one of the most important parts of the machine.
The functioning of tokamaks like ITER is largely based on the plasma, the electrically loaded substrate and brought to a temperature of more than 100 million degrees where the fusion reactions take place. To make it emerge, you must first bring a great amount of energy to a mixture of tritium and deuterium gaseous. All the challenge is then to maintain this plasma at a good distance from the reactor walls, but also and above all to stabilize it, failing which the reaction cannot cross the famous “ignition threshold” which allows him to hear himself.
The central solenoid, the spine of the reactor
To achieve this, engineers rely on gigantic co -binding coils of several hundred tonnes, which generate an extremely intense magnetic field. Most of these magnets are positioned around the room, with one exception: The gigantic central solenoid positioned in the middle of the “donut”, which will become The most powerful superconductive magnet on the planet.
The latter will be responsible for a mission of the utmost importance: to create a current in the plasma. This flow of loaded particles is absolutely crucial. He actively participates in the rise in temperature, and he also plays a decisive role in stabilizing the reaction. It is therefore one of the most important organs of the reactor.
Mummons installing this engineering jewel is anything but obvious. It is indeed composed of Six modules each weigh 121 tonnesand the whole must be positioned with an error margin of a few millimeters! In order to ensure that he plays his role to perfection, so you have to start by building a gigantic support structurea kind of high-tech scaffolding of several thousand pieces which must take gigantic constraints without moving an inch. A colossal engineering challenge.
« The first role of the structure is to maintain the six central solenoid modules in position with strict tolerances, of the millimeter “Explains Kevin Freudenberg, technical director of ITER engineering in the United States. “” The real challenge then arises during operation. At key moments, the vertical force which is exercised on the stack of modules can reach 60 meganewtons, more than double the force generated by a takeoff rocket. »
A key step in construction
8 American companies specializing in structural engineering and high precision manufacturing worked hand in hand for almost ten years to design and build this colossal structure. This key step is finally completed: in a press release, the ITER consortium announced that The last elements of this gigantic cage were finally delivered on the Cadarache site.
It is a very important milestone in the history of the reactor. Indeed, this means that the assembly of the central solenoid will soon be finished. The first four modules are now in place and the last two should be stacked by the end of the yearonce the last elements of the freshly received reinforcement have been assembled and rigorously tested.
But that does not mean that engineers and workers are finally at the end of their sorrows, far from it. The next big step will be to integrate this metal monster into the structure of Tokamak. This will take the solenoid to this other peripheral superconductive magnets, then make sure that the whole will be perfectly aligned so that the first plasmas are as stable as possible. It will then be necessary to install the rest of the structural components and instruments that will allow you to confine the plasma, starting with the vacuum chamber itself.
Some of the most interesting steps in construction are therefore starting to point the nose, and it will be fascinating to follow the progress of this unique engineering effort. Hopefully the next steps will now follow one another regularly, in a context where project managers have recently been forced to postpone the date of the first plasma.
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