Scientists from Peter the Great Polytechnic University of St. Petersburg (SPbPU) are the first in the world to detect and experimentally determine exactly where plasma oscillations, known as Alfven waves, occur inside an experimental fusion installation. The university's press service told that this discovery will help control these processes in the future, prevent large energy losses and protect the reactor walls, which is an important step towards creating safe and efficient fusion power plants.
“First, we discovered experimentally exactly where Alfvén oscillations arise and exist within the toroidal system. <...> Second, we found that different types of Alfvén oscillations and their harmonics can have different local positions,” the press service quotes Alexander, candidate of physical and mathematical sciences, head of the scientific laboratory “High-temperature plasma diagnostics” of the Institute of Physics-Mechanics of St. Petersburg Yashina Polytechnic University.
To date, there are only theoretical models of the behavior of these oscillations. For the first time, researchers in St. Petersburg was able to practically test the theory in real installation conditions – the Globus-M2 spherical tokamak at the Institute of Physics-Technology is named after. AF Ioffe.
Tokamaks are toroidal (doughnut-shaped) installations in which strong magnetic fields trap hot plasma at hundreds of millions of degrees, preventing it from touching the walls. They recreated conditions similar to processes on the Sun to generate fusion energy. Alfven oscillations arising in such plasma have a dual effect. On the one hand, they help transfer energy, but on the other hand, they can cause strong plasma emissions and significant heat loss, risking damage to the installation. Therefore, learning how to manage them is extremely important.
Alfven oscillations are waves that “run” along magnetic field lines in the plasma. They can accelerate the loss of high-energy particles. For future fusion reactors, such as the international ITER under construction, the allowable loss of such particles is strictly limited (no more than 2%).
Uncontrolled Alfven oscillations could cause much more serious damage, threatening the reactor's operation.
The experimental data that St. Petersburg on the precise positioning of these oscillations is a valuable contribution to solving one of the main problems of controlled thermonuclear fusion, aiming to increase both its efficiency and safety.
