Francois Ryter from Germany’s Max Planck Institute for Plasma Physics has won the IAEA’s 2017 Nuclear Fusion Journal Prize for experimental work elucidating a mechanism that can trigger a fusion plasma (see video) to a state that allows the fusion device to operate under high performance, the journal’s Board of Editors has announced. The work was carried out on the ASDEX Upgrade tokamak.

Initiating and sustaining fusion takes a lot of energy and a key issue is being able to achieve the condition in which the fusion output power exceeds the auxiliary input power supplied from outside to sustain the reaction. The operation of a fusion device, such as the International Thermonuclear Experimental Reactor (ITER, see box), in so called high (H)-mode is critical to achieving this condition.

The paper, by a group of researchers led by Ryter, is entitled ‘Experimental evidence for the key role of the ion heat channel in the physics of the L–H transition’. It has shown that, of the several factors that had been considered as potential triggers for the transition from the low (L)-mode confinement state of the device to H-mode, ion heat flux is key. This video shows the transition of the plasma from L-mode to H-mode inside a tokamak. The transition occurs at around 0:22.

The findings can improve the capability to predict the amount of input power required to operate the device in H-mode. Filling this kind of gap in the understanding of magnetic confinement plasma physics can facilitate the preparation for the operation of future fusion reactors for energy production.

Nuclear fusion bears the promise of an almost inexhaustible source of clean energy akin to natural processes occurring in the sun. Fusion fuel – produced from water and lithium – is in principle so abundant that fusion energy would be inexhaustible and deployable everywhere on the planet. However, harnessing commercially-viable fusion power has serious technological challenges such as the ability to achieve temperatures exceeding 100 million degrees Celsius, 10 times higher than in the core of the sun, while confining the hot fusion fuel to the vessel within the reactor. Additionally, finding the right material to construct the fusion reactor, and developing the mechanism that will be used to extract and convert the enormous amount of energy that is produced, are among the other major challenges in the quest to produce electricity from fusion.

To make its production in a controlled manner a reality, the IAEA is supporting international efforts in coordinated research and development that involves nuclear physicists, material scientists, nuclear data specialists, metallurgists and plasma experts.

“Delivering an important piece of work on L–H transition physics, Ryter et al present a systematic and rigorous experimental study revealing the key role of the ion heat flux at the plasma edge,” the journal’s chair of the Board of Editors, Rich Hawryluk, said in a statement announcing the award. “This is important for better understanding of the future operation of ITER and other experiments,” he said.

Since 2006, the IAEA has celebrated excellence in its journal, Nuclear Fusion, by means of an annual prize. This is awarded to the authors of papers which are judged to have made the greatest impact in the two years following the paper’s publication. The selection process involves consideration of citations and recommendations by the journal’s Board of Editors. The shortlist and eventual winner are decided by confidential votes by the journal Board.

The award winning paper can be accessed here.

Nuclear Fusion was launched in 1960. It is the most frequently cited journal in the field. It is steered by an international board of eminent scientists, who give direction on content and policy. It facilitates communication between research groups worldwide, disseminating results and concepts and aiding collaboration. The journal now regularly receives submissions from over 30 countries and its geographical balance reflects the significant body of work being done globally in fusion. Every major advance in fusion has been reflected in the journal’s published articles.