In the quest to make fusion energy a viable and safe reality, scientists are tackling some of the most complex challenges in physics. One such challenge is managing tokamak disruptions, sudden and uncontrolled events that can threaten the integrity of the fusion reactor. A recent study published in the journal *Nuclear Fusion* and translated into English offers a promising approach to mitigating these disruptions, potentially paving the way for more stable and efficient fusion reactors.
The conventional method for managing thermal quench (TQ) in tokamak disruptions involves injecting high-Z impurities, which radiate away the plasma’s thermal energy before it can damage the reactor wall. However, this approach has a significant downside: it leads to a robust Ohmic-to-runaway current conversion due to the low post-thermal-quench electron temperature. This is where the new research comes into play.
Jason Hamilton, a scientist from the Theoretical Division at Los Alamos National Laboratory, and his team have proposed an alternative strategy. Instead of using high-Z impurities, they suggest injecting low-Z elements like deuterium or hydrogen. The goal is to slow down the thermal quench and align it with the current quench (CQ), thereby controlling the energy loss to the wall more effectively.
Hamilton explains, “By boosting the hydrogen density, we can cool the plasma at approximately the original pressure. This approach not only controls the energy loss but also increases the plasma’s collisionality, putting it into the Braginskii regime, where parallel transport is significantly enhanced.”
The team used 3D MHD simulations with the PIXIE3D code to investigate this approach. Their findings indicate that a sufficient low-Z injection can slow down the thermal quench rate to about 20 milliseconds, aligning it with the current quench timescale for a 15 MA ITER plasma. This alignment is crucial for maintaining the stability of the fusion reaction and preventing damage to the reactor.
The implications of this research are far-reaching. By mitigating tokamak disruptions more effectively, fusion reactors can operate more safely and efficiently. This could accelerate the commercialization of fusion energy, providing a clean and virtually limitless power source for the future.
Hamilton adds, “Our study shows that by understanding and controlling the transport processes in the plasma, we can significantly improve the stability of fusion reactions. This is a step forward in making fusion energy a practical reality.”
As the world seeks sustainable energy solutions, advancements like these bring us closer to harnessing the power of fusion. The research not only offers a technical solution but also highlights the importance of innovative thinking in overcoming the challenges of fusion energy. With continued investment and research, the dream of clean, abundant energy could soon become a reality.