Significant progress has been made in nuclear fusion reactions in increasing plasma density and maintaining denser plasma, reaching the “sweet spot” necessary for power generation. This represents an important step forward in the field of nuclear fusion power, although the advent of commercial reactors will still take several years.
Currently, one of the main pathways to nuclear fusion power generation is the use of Tokamak reactors. This special-shaped device consists of magnetic coils surrounding its exterior, which can promote nuclear fusion at ultra-high temperatures with a strong magnetic field, temperatures even exceeding those inside the sun.
For a long time, scientists have considered that a decisive limiting factor in nuclear fusion reactions is the so-called Greenwald limit, which states that once the fuel density surpasses this point, the plasma cannot be confined by the magnetic field, leading to reactor damage. Increasing density is key to increasing energy output, as research shows that the power generation capacity of Tokamak reactors is directly proportional to the square of the fuel density.
Researchers at General Atomics in the United States have achieved an increase in plasma density for high confinement steady-state operation through a method. Using this method, they achieved stable operation for up to 2.2 seconds with average density exceeding the Greenwald limit by 20% in the DIII-D National Fusion Facility’s Tokamak reactor.
Although breakthroughs have been made in the past, stability and sustainability were not ideal. In this experiment, the key indicator, the energy confinement enhancement factor H98 (y,2), was greater than 1, showing that the plasma was successfully stabilized in the right position, indicative of steady-state operation.
According to Gianluca Sarri of Queen’s University Belfast, UK, the ability to demonstrate steady-state operations means that the optimal state can be maintained for a long time. Sarri suggests that extending this research to larger facilities will contribute to achieving continuously increasing output power and energy gains.
It is noteworthy that the DIII-D experiment uses a fusion of various existing technologies. The outer radius of the plasma chamber in the DIII-D facility is only 1.6 meters, and there are doubts about whether this technology is suitable for larger-scale facilities such as the International Thermonuclear Experimental Reactor (ITER).
Nevertheless, this experiment is a positive indication for the future of nuclear fusion power generation. Researchers point out that the design of most reactors requires both high confinement and high density, which has been achieved experimentally for the first time.
While the next steps may require substantial investment, and current research is moving in multiple directions, it is hoped that the results of this experiment will provide a focus for global R&D efforts.
