China Sets New Record for Nuclear Fusion
Researchers at the Experimental Advanced Superconductor Tokamak (EAST) in Hefei, China have made another incredible breakthrough in harnessing nuclear fusion.
EAST researchers have been successful in pushed super-hot plasma to densities far beyond what had previously been thought possible.
Fusion power output rises roughly with the square of plasma density. This breakthrough allows for more particles of fusion fuel to be safely packed into the reactor core, increasing its production capability.
Until now, fusion experiments have been restricted by the Greenwald density limit, a threshold above which plasma becomes unstable and leaks from the magnetic cage. This dumps heat on the outer walls, which can lead to a violent disruption.
Plasma control and confinement remain major hurdles in the development of stable nuclear fusion using tokamaks. The process of deuterium-tritium fusion requires fuel reach 150 million degrees Celsius under intense pressure in order to create the desired reaction.
Usually operating within 0.8-1.0 parameters of the Greenwald limit, EAST researchers were able to reach line average electron densities between 1.3-1.65 beyond the limit. This was achieved by finetuning how EAST started each plasma pulse.
Reports indicate the reactor vessel was prefilled with a relatively high pressure of deuterium gas then applied a type of microwave heating called electron cyclotron resonance heating to help the standard Ohmic startup chip activate the plasma.
This allowed the team greater control over how waste heat was handled, reduced the amount of wall material knocked into the plasma, and cut energy losses. Under these balanced conditions, the plasma was allowed to climb without triggering instability alarms and surpass the long-standing ceiling.
It’s a major milestone for nuclear fusion development that also provides the first evidence for the concept of plasma wall self-organisation.
Developed by theorist Dominique Franck Escande and colleagues at the French National Center for Scientific Research and Aix-Marseille University, the theory posits that if the plasma and the metal wall reach just the right balance, a new density free regime appears where the usual limit effectively moves far upward. Although the wall still erodes and emits impurities in this state, they no longer trigger cooling and confinement disruption.
The achievement is the latest in a series of accomplishments for EAST and other fusion research programs around the world. Last January, EAST set a new benchmark by generating a sustained plasma loop for 1066 seconds, more than doubling its own previous record of 403 seconds.
Since the invention of the first tokamak in the 1950s to China’s latest breakthrough, the story of nuclear fusion is one of human ingenuity, imagination, and perseverance. The quest to reproduce the power of the Sun has become a global enterprise, with more than 40 companies around the world totalling $7 billion in investment dedicated to solving the problem.
EAST is part of the International Thermonuclear Experimental Reactor (ITER), an international research and engineering project based in France. The same strategy designed by the Chinese will greatly inform future ITER operations as well as the design of advanced reactors.
Professor Ping Zhu, one of the scientists who led the recent EAST experiments, said: “The findings suggest a practical and scalable pathway for extending density limits in tokamaks and next generation burning plasma fusion devices.”
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These are small steps on the long road to achieving a stable and viable source of nuclear fusion but its progress, nonetheless.
China’s ultimate goal is to create ‘artificial suns’ capable of producing vast, near limitless, energy with minimal waste and negligible environmental impact. Such a feat would herald a new era of unprecedented scientific discovery, fuelling humanity and its endeavours for generations to come.
Once researchers can tame and control variables within the fusion process itself, the next biggest challenge is preparing it for commercial market viability, which is still decades away.
Currently, advancements in nuclear fusion have occurred in small-scale laboratory setups under experiment conditions, not industrial-size power plants that have a meaningful impact on cutting power costs for everyday consumers.
While there are still many hurdles to overcome, a new source of clean energy is possible. The work being done today will provide a framework for powering the future without reliance on fossil fuels or renewable energy.
