Amazing Laser Application 9: Fusion!

What's the application? The goal of laser ignition fusion experiments is to heat and compress a target to the point where the nuclei of the atoms making up the sample fuse together to form a new, heavier nucleus, releasing energy in the process. Nuclear fusion is, of course, what powers stars, and creating fusion in the laboratory has been the holy grail (well, a holy grail, at any rate) of nuclear physics research for the last sixty-plus years.

What problem(s) is it the solution to? 1) "Can we create fusion reactions in a laboratory setting on Earth?" 2) "How can we get more helium without mining it from the Moon?"

How does it work? The basic idea is appealingly simple: Get a whopping hug laser, focus it down onto a target, and BLAM! instant star:

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In practice, it's much more difficult than the idea makes it sound-- you can very easily blast a target into plasma, but getting that plasma hot and dense enough to let fusion occur requires incredible care in arranging the beams so that the target is uniformly illuminated, and collapses in a symmetric manner.

But stripped down to its essence, that's really all there is to gigantic experiments like the National Ignition Facility (WARNING: auto-playing video with sound): You just build the biggest laser you can, focus it down to a point, and blast away.

Why are lasers essential? You could theoretically do this with any really bright light source, but the current record is about 0.7MJ of energy in the pulse hitting the target, which would be awfully tough to arrange without a laser. Having the light pulse in laser form makes it vastly easier to direct and focus it appropriately.

Why is it cool? Dude, they're, like, bringing the sun down to Earth!

Controllable fusion reactions in a lab setting would be a huge boon to nuclear research. And, of course, if scientists can figure out a way to generate power from nuclear fusion, they could be gunned down by assassins hired by the Eeeeevil oil companies provide clean energy for the entire world.

Why isn't it cool enough? They've made a lot of progress recently, but have not actually achieved fusion yet, though they hope to reach the required pulse energies this year, maybe. Commercial fusion power generation is twenty years off, and expected to remin that way for the next twenty-odd years.

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The nuclear and high-energy physics experiments never fail to come up with the coolest looking hardware. Seriously, everyone needs to check out the galleries on that NIF site. The target apparatus looks exactly like the sort of thing that should be powering a starship. I thought at first that the image you put up was some fanciful artist's conception, maybe pulled off of some decades-old pulpy scifi magazine. But no, it's just an earlier experiment in the field.

Same goes for all of the big particle accelerators... the LHC certainly looks more badass than any doomsday device dreamed up by hollywood.

By lazybratsche (not verified) on 19 Apr 2010 #permalink

...wait, so shouldn't this be on the list of best POSSIBLE laser applications?

Along with mind control, scalable quantum computing and world domination...err, forget the last one.

Awesome photo. This is the kind of stuff that Obama's Sect'y of Energy, Stephen Chu is into. And if I'm not mistaken, there's no question that this will will create fusion. As with the ITER Tokomak, and a number of other research approaches now being funded by DoD, and DoE, and showing promise towards reaching break-even, fusion isn't the trick so much these days. The trick is getting more energy out of the system than it takes to "burn" the hydrogen. As for 20 years in the future, not unlikely but once fusion excedes break even the game will be changed when it comes to energy, and just what these next 20 years will look like could be very very interesting.

Well, Tokamak fusion has already more-or-less reached break-even, the problem is that commercial generation requires 20:1 or so. The Joint European Torus reached 0.7 back in 1997 for a few seconds, the JT-60 has exceeded that since then. ITER should reach ~10:1 for ~1000 secs, and provide the information necessary to build DEMO: 15% larger, 30% greater plasma density, capable of (hopefully...) 25:1, and generating power.

By Lurker #753 (not verified) on 20 Apr 2010 #permalink