A recently completed coordinated research project (CRP), F43019 (Atomic and Molecular Data for State-resolved Modelling of Hydrogen and Helium and their Isotopes in Fusion Plasma), has improved our understanding of fundamental atomic and molecular processes necessary for developing fusion power. Specifically, the project generated and evaluated data for collisions of simple atoms and the resulting radiative processes. Fusion reactions can be induced in a form of matter called plasma, which consists of extremely hot gases that are electrically charged.
In the core of the Sun, fusion reactions between hydrogen atoms take place within dense plasma—the process powers our home star and makes it shine. These reactions require incredibly high energies to convert tiny amounts of mass into vast amounts of pure energy (according to Einstein’s famous equation E=mc2). The benefits of making controlled fusion a viable power source for humanity would be staggering and far-reaching—unlimited energy being the most striking example.
Even for the simplest of atoms (hydrogen), our knowledge of the quantum processes involved in plasma physics has contained important gaps, even as ambitious projects such as ITER (located in France) have worked to make fusion power commercially viable.
Within a fusion reactor, the core reactions are happening at enormously high temperatures, which dissipate rapidly in the outer regions of the fusion chamber, closer to its inner walls. Understanding the physics of this region, the so-called plasma edge, is crucial for protecting the inner walls of the physical reactor and for controlling the core fusion reaction itself. Part of the technical challenge of controlling fusion for power generation is to model the atomic and molecular processes occurring in the edge plasma.
This CRP, which involved 12 outside research institutions in collaboration with the IAEA, has generated crucial data that will help scientists create these models for hydrogen atoms and relevant molecules, contributing to the solution of technical challenges for controlling nuclear fusion. These models will enable higher levels of control of the fusion edge plasmas, and thus of the core fusion reactions themselves.
"The global effort to achieve controlled fusion needs to be supported with research from many different areas,” said Bastiaan Braams, who initiated this project at IAEA and who is now at Centrum Wiskunde & Informatica (CWI) in the Netherlands. "The data from this CRP have expanded our capability to simulate the complicated processes that go on in fusion devices, giving us a clearer picture of what’s happening in our experimental reactors."
This project studied collisions and reactions of hydrogen and helium in fusion devices, but primarily covered reactions of hydrogen, including the isotopes deuterium and tritium and their various molecules and molecular ions. This narrower focus allowed the researchers to dig deeper into the data and to progress towards developing a critically evaluated database of collision cross sections (i.e. the amount of physical space around a particle which needs to be breached by another particle to induce a collision) and reaction rate coefficients (i.e. a measurement of the speed of a chemical reaction).
That rich store of new information will be added to the IAEA’s ALADDIN database of nuclear data, and has already resulted in 68 peer reviewed journal articles. The final CRP publication was published in the journal, Atoms.
More work is yet to be done before controlled fusion is achieved and becomes commercially viable, but the data produced by this collaboration has helped fill in some critical knowledge gaps that will enable previously intractable technical problems to be aggressively pursued and hopefully solved.