The construction of ITER is on the right track. The agenda planned by EUROfusion, the international consortium responsible for the development of this experimental nuclear fusion reactor, is gradually meeting deadlines. And, if nothing goes wrong, in 2025 the assembly of this highly complex machine will be completed and they will begin the first tests with plasma.
There is no doubt that this will be an important milestone, but there will still be several challenges ahead that will have to be overcome to make possible the arrival of commercial nuclear fusion, which is estimated, according to EUROfusion, for the 1960s. The materials that will be used in the internal lining of the DEMO vacuum chamber will be commissioned by the IFMIF-DONES project. And there is no doubt that it is a great challenge.
But there is another major challenge that we cannot ignore: it is essential to understand how does plasma behave, which is at a temperature close to 150 million degrees Celsius, to stabilize it. It is necessary to solve this problem to be able to sustain the nuclear fusion reaction over time, and in this area the threat comes from the turbulences that originate naturally in the outermost layer of the plasma, which is precisely the one that is most near the walls of the vacuum chamber.
The turbulences that originate in the ‘crust’ of this very high-temperature gas are somewhat similar to the deflagrations emitted by our Sun, but the fact that the plasma is confined by a magnetic field housed inside a chamber forces technicians to prevent it from coming into direct contact with the container walls. Otherwise, if it touches them, it will degrade them and the nuclear fusion reaction will not be able to sustain itself.
Researchers are currently working on several strategies that seek to solve this problem, and one of the most promising tries to take advantage of the stabilizing effect they have on plasma. the ionized helium-4 nuclei (We talk about it in some depth in the article that I link right here). This is the line that a research group from MIT is following, and precisely another scientific team from this institution has made a very important discovery in this same area.
Deep learning helps us understand how plasma behaves
Even if the IFMIF-DONES project fulfills its mission and manages to find the inner lining materials that will allow the vacuum chamber to withstand the impact of high-energy neutrons, a challenge will remain: preventing the heat flows from the plasma as turbulence damage the walls of this chamber. To achieve this, it is necessary to know precisely how plasma behaves, which has led a group of MIT researchers to develop a mathematical model that seeks to predict it.
The curious thing is that in the elaboration of this turbulence model, deep learning is playing an absolutely essential role, which serves to test it and assess its predictive ability. In fact, in two of the articles they have recently published (we leave you the links just at the end of this text), these researchers explain in detail the strategy they are using to ensure that deep learning allows them to infer new knowledge about the behavior of the plasma. Your purpose is to refine your turbulence model as much as possible to accurately stabilize the plasma.
This statement by Abhilash Mathews, one of the MIT researchers, describes their approach very well: “A successful theory must be able to predict what you are going to observe, such as temperature, density, electric potential or flux. In fact, it is the relationship that exists between all these variables that fundamentally defines a theory of turbulence. Our work in essence analyzes the dynamic relationship that exists between two of these variables: the electric field of the turbulences and the pressure of the electrons”.
The turbulences to which plasma is subjected are much more complex and difficult to predict than those of water or air.
From his words it is clear how difficult it is to predict the behavior of the plasma at extremely high temperatures confined inside the nuclear fusion reactor. In fact, according to these researchers, the turbulence to which this gas is subjected they are much more complex than those that we can observe in other fluids, such as air or water. Still, the advances being made by these and other scientists invite us to view the future of nuclear fusion with reasonable optimism. Much remains to be done, but the outlook is hopeful.
Cover image: CFS
More information: Physical Review E | American Institute of Physics
