Fusion 'breakthrough' heralds cleaner energy

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Scientists may have come close to producing a type of nuclear fusion, the energy that powers the Sun and hydrogen bombs, in a glass beaker on a laboratory bench.

A team led by Rusi Taleyarkhan, of the prestigious Oak Ridge National Laboratory in Tennessee, claims to have generated temperatures of up to 10 million degrees Celsius by squashing small bubbles in liquid acetone with high-pressure sound waves.

Such intense heat and pressures inside the collapsing bubbles would be sufficient to generate nuclear fusion. The scientists say their results suggest, but do not confirm, that such fusion has indeed happened inside a glass beaker the size of three coffee cups. The claims, made in a study to be published in the journal Science on Friday, have already been greeted with scepticism by other researchers who believe the critical signs of fusion are still lacking.

Dr Taleyarkhan insisted the experiment is "table-top physics", and if the conclusions are found to be true the research could eventually lead to fusion power plants generating almost limitless amounts of relatively clean energy.

Harnessing the power of nuclear fusion has been the holy grail of physics for decades because it could potentially use water as the fuel with very little pollution. But claims that "cold fusion" had been achieved in 1989 by Stanley Pons, of the University of Utah, and Martin Fleischmann, of Southampton University, were never independently verified. The present research focuses on "acoustic cavitation", in which the pressure of a sound wave creates then collapses a bubble in a liquid. The first sound wave stretches the liquid, which causes a bubble to form. A second wave then compresses the bubble so hard it bursts and releases a brief flash of light in a process known as sonoluminescence.