Scientists at the University of California in Los Angeles have demonstrated desktop nuclear fusion by simply heating a lithium tantalate crystal soaked in deuterium gas. However, the technique produces far too few neutrons to be practical for commercial use, so it's sadly not a matter of free-power-for-everyone next week, New Scientist reports.
Seth Putterman's UCLA team used previous research by James Brownridge at the State University of New York - which produced X-rays from lithium tantalate by heating the crystals in a dilute gas - as the basis for its experiment. When Brownridge turned up the heat on the lithium tantalate, the pyroelectric properties of the crystal created an electric field provoked by the migration of positive and negative charges to opposite ends of the crystal. As NS explains, the electric field "strips electrons from the gas molecules and accelerates them to huge energies. The electrons then collide with stationary nuclei in the crystal and generate X-rays."
Putterman realised that the electric fields generated were sufficiently strong to spark nuclear fusion in deuterium - a "mind-boggling" 107 electronvolts as the excited boffin put it.
The recipe for UCLA nuclear fusion is as follows: Bathe lithium tantalate in deuterium gas. Cool to -33°C. Heat to 7°C over three-and-a-half minutes. Wait for electric field to "accelerate deuterium nuclei over a distance of 1 centimetre to energies in excess of 100 kiloelectronvolts". Watch as nuclei then collide and fuse with deuterium nuclei that had "permeated the surface of the crystal lattice".
And, if you get your recipe right, you should cook up "400 times more neutrons than found in background measurements".
Sounds good, but this represents a few hundred neutrons per second - way short of the millions of neutrons a second you'd need for a commercial neutron generator. Accordingly, hopes for the technique are at present modest. Putterman says it might one day power microthrusters for miniature spacecraft, while Nigel Hawkes, a nuclear physicist at the UK's National Physical Laboratory, cautioned: “It’s too early to say where this might lead.”
In the meantime, Putterman hopes to up the neutron yield by "operating at lower temperatures and by using an array of crystals". ®