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2019-12-15 00:22 |
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HZDR scientists want to use quantum mechanics to trigger the fusion of atomic nuclei 0Fi&7%
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Nuclear physics usually involves high energies, as illustrated by experiments to master controlled nuclear fusion. One of the problems is how to overcome the strong electrical repulsion between atomic nuclei which requires high energies to make them fuse. But fusion could be initiated at lower energies with electromagnetic fields that are generated, for example, by state-of-the-art free electron lasers emitting X-ray light. Researchers at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) describe how this could be done in the journal Physical Review C. qf
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During nuclear fusion two atomic nuclei fuse into one new nucleus. In the lab this can be done by particle accelerators, when researchers use fusion reactions to create fast free neutrons for other experiments. On a much larger scale, the idea is to implement controlled fusion of light nuclei to generate power - with the sun acting as the model: its energy is the product of a series of fusion reactions that take place in its interior. %M_5C4&6
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For many years, scientists have been working on strategies for generating power from fusion energy. "On the one hand we are looking at a practically limitless source of power. On the other hand, there are all the many technological hurdles that we want to help surmount through our work," says Professor Ralf Schützhold, Director of the Department of Theoretical Physics at HZDR, describing the motivation for his research. /^>yDG T,0
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Tunneling at a high level, to be accessible soon 9v2(cpZ
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In order to trigger nuclear fusion, you first have to overcome the strong electrical repulsion between the identically charged atomic nuclei. This usually requires high energies. But there is a different way, explains the co-author of the study, Dr. Friedemann Queißer: "If there isn't enough energy available, fusion can be achieved by tunneling. That's a quantum mechanical process. It means that you can pass (i.e., tunnel) through the energy barrier caused by nuclear repulsion at lower energies." mlmXFEC
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This is not some theoretical construct; it really happens: The temperature and pressure conditions in the sun's core do not suffice to overcome the energy barrier directly and enable hydrogen nuclei to fuse. But fusion happens nonetheless because the prevailing conditions allow the fusion reaction to be sustained thanks to a sufficiently high number of tunneling processes. ~"ij,Op,3
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In their current work, the HZDR scientists are investigating whether controlled fusion could be facilitated with the assistance of tunneling processes using radiation. But that is also a question of energy: the lower it is, the lesser the likelihood of tunneling. Up to now, conventional laser radiation intensity was too low to trigger the processes. `Wf)qMb
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XFEL and electron beams to assist fusion reactions 9ywPWT[^
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This could all change in the near future: With X-ray free electron lasers (XFEL) it is already possible to achieve power densities of 10^20 watts per square centimeter. This is the equivalent of approximately a thousand times the energy of the sun hitting the earth, concentrated on the surface of a one-cent coin. "We are now advancing into areas that suggest the possibility of assisting these tunneling processes with strong X-ray lasers," says Schützhold. G3G"SJ np
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