The importance of the US National Ignition Facility (NIF – see above) is endorsed by nuclear weapons scientists who want to investigate the conditions inside a nuclear explosion without testing, and by advocates of fusion energy. It will be the first device to ignite a controlled fusion reaction.
By focusing an enormous 1.8 megajoules of energy on a pellet of deuterium–tritium fuel a couple of millimetres in diameter, in a pulse lasting only three nanoseconds, the NIF should make the pellet implode, causing its centre to ‘ignite’ in a brief, self-sustaining fusion reaction.
Fusion in the pellet could be induced either directly, by firing lasers at it from all sides, or indirectly, by placing it in a cylindrical target, or ‘hohlraum’, about one centimetre long, and using the laser pulse to induce X-rays from the hohlraum which would compress the pellet.
Even short of ignition, laser experiments such as the NIF cause some fusion in their targets. Nuclear weapons scientists can therefore study the behaviour of materials in extreme conditions, and refine computer models of nuclear explosions without nuclear testing.
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Macilwain, C. Nuclear fusion without weapons testing. Nature 403, 469 (2000). https://doi.org/10.1038/35000712
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DOI: https://doi.org/10.1038/35000712
