Scientists at the US Department of Energy's Princeton Plasma Physics Laboratory have found a way to stabilize super-hot plasma inside fusion chambers, similar to those found in the bowels of stars. This was announced in a press release on Phys.org.
Scientists at the Princeton Plasma Physics Laboratory at the US Department of Energy. Photo: Elle Starkman / PPPL Office of Communications.
Plasma instability is one of the main problems of maintaining thermonuclear fusion reactions inside tokamaks. Due to the so-called tearing modes, magnetic islands are formed, which grow, stop fusion reactions and can even damage the installation.
In the 1980s, physicists discovered that using radio frequency waves to control plasma flows prevents discontinuous modes from developing and reduces the risk of failure. In the new work, the scientists determined that small perturbations in plasma temperature could also contribute to stabilization.
Thus, temperature disturbances in plasma increase the strength of the current flowing through them and the amount of radio-frequency energy absorbed by the islands. The disturbances themselves and their influence on the absorbed energy depend on each other in a complex nonlinear manner. Since the electric current required to stabilize the plasma is sensitive to changes in temperature, it becomes possible to achieve conditions where all three factors contribute to the concentration of radio frequency energy inside the islands, which prevents their further growth.