Monday, December 12, 2022

Inertial Confinement

This result is a major breakthrough in fusion science.  The Lawrence Livermore National Laboratory uses the largest laser in the world to compress heavy hydrogen to conditions similar to those in the centre of the sun.  The lasers enter the ends of a centimetre-scale cylinder, hitting its inner walls, making them glow x-ray hot.  These x-rays then heat a sphere at the centre that contains the nuclear fuel.  The outside of the sphere vaporises and becomes a plasma, that rushes off the surface, creating an imploding "spherical rocket" which in a few billionths of a second reaches velocities of order 400 kilometres per second.  The subsequent "crunch" at the centre is tailored in a specific way to make a hot spark in the middle, and the density of the compressed "fuel" surrounding the spark is so great that the nuclear fusion reaction takes place in about a tenth of a billionth of a second -- faster than the tiny hot sphere can fly apart.  It is thus confined by its own inertia, and thus this method of fusion is called inertial confinement fusion.

-- Professor Justin Wark, Professor of Physics at the University of Oxford and Director of the Oxford Centre for High Energy Density Science, in comments about recent advances in nuclear fusion at Lawrence Livermore National Laboratory, 12 December 2022

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