The Light Fantastic

James Randerson, writing in The Guardian, describes a new initiative in Europe to use lasers to try to create a working fusion reactor.

It's a clean source of energy using fuel that can easily be extracted from sea water, and it isn't owned by Saudi Arabia. We're talking about fusion - and a multinational project led by British researchers that aims to use high-powered lasers to produce nuclear fusion, the same physical reaction powering the sun. If they succeed, they could solve the approaching world energy crisis without destroying the environment.

Although the team admits a commercial fusion reactor is still decades away, it believes using lasers to spark fusion shows great promise. The EU has agreed to fund the setup costs for a seven-year research project called HiPER (High Powered laser Energy Research) to build a working demonstration reactor. But preparing for that stage - requiring the collaboration of 11 nations including Germany, France, Canada and Russia - is expected to cost more than €50m (£35m). Building the reactor itself will cost more than €500m.

Money machine

Why such investment? Because if we can control a fusion generator, it will be self-powering, offering abundant excess energy (to convert in turn to electricity) from virtually unlimited fuel. On top of this, its waste products won't contribute to climate change or pose the long-term waste storage problem that fission - our present nuclear generation system - poses. And we desperately need new electricity sources.

But fusion is infamous for its grand claims, massive grant proposals and, so far, limited success. Physicists joke that they've been saying fusion power is 40 years away for the past 40 years. So far it's only been used in the H-bombs exploded in tests, but that was uncontrolled.

Up to now, most attention has been on so-called magnetic fusion (see panel), in which a powerful magnetic jacket brings two different isotopes of hydrogen at enormously high temperatures close enough to fuse. That releases huge amounts of energy. It's been done - but no reactor has been built large enough to generate more energy than is put in via the magnets.

It's an interesting read, but I was a bit surprised at this passage:

Laser fusion involves some mind-numbing science. CLF's laser, called Vulcan, is the most powerful laser in the world: it can focus 500 joules of energy (about the same required to lift 50 apples by 10m) into a laser burst just 40 femtoseconds (40 x 10-15) long - equivalent to one second in a million years. During that period, it's applying 10,000 times more energy than the National Grid generates

I'm not sure how to square that claim with other information. The University of Rochester (New York) has been conducting laser fusion experiments since 1970. I've known about that place for decades, even though I do not follow fusion research closely. Their OMEGA facility is supposed to be operational this year and will be able to focus as much as 40,000 joules of energy from 60 lasers - which calcs out to slightly more than 666 joules per laser. Here's the website for the UofR's Laboratory for Laser Energetics which describes their facility. Unless I'm misreading something, the European project is far, far behind the one at Rochester.