Laser fusion test results raise energy hopes

[jimmy olsen]

Frickin laser beams!

http://news.bbc.co.uk/2/hi/science/nature/8485669.stm

Laser fusion test results raise energy hopes
By Jason Palmer
Science and technology reporter, BBC News

A major hurdle to producing fusion energy using lasers has been swept aside, results in a new report show.

The controlled fusion of atoms - creating conditions like those in our Sun - has long been touted as a possible revolutionary energy source.

However, there have been doubts about the use of powerful lasers for fusion energy because the "plasma" they create could interrupt the fusion.

An article in Science showed the plasma is far less of a problem than expected.

The report is based on the first experiments from the National Ignition Facility (Nif) in the US that used all 192 of its laser beams.

Along the way, the experiments smashed the record for the highest energy from a laser - by a factor of 20.

Star power

Construction of the National Ignition Facility began at Lawrence Livermore National Laboratory in 1997, and was formally completed in May 2008.

The goal, as its name implies, is to harness the power of the largest laser ever built to start "ignition" - effectively a carefully controlled thermonuclear explosion.

It is markedly different from current nuclear power, which operates through splitting atoms - fission - rather than squashing them together in fusion.

Proving that such a lab-based fusion reaction can release more energy than is required to start it - rising above the so-called breakeven point - could herald a new era in large-scale energy production.

In the approach Nif takes, called inertial confinement fusion, the target is a centimetre-scale cylinder of gold called a hohlraum.

It contains a tiny pellet of fuel made from an isotope of hydrogen called deuterium.

During 30 years of the laser fusion debate, one significant potential hurdle to the process has been the "plasma" that the lasers will create in the hohlraum.

The fear has been that the plasma, a roiling soup of charged particles, would interrupt the target's ability to absorb the lasers' energy and funnel it uniformly into the fuel, compressing it and causing ignition.

Siegfried Glenzer, the Nif plasma scientist, led a team to test that theory, smashing records along the way.

"We hit it with 669 kiloJoules - 20 times more than any previous laser facility," Nif's Siegfried Glenzer told BBC News.

That isn't that much total energy; it's about enough to boil a one-litre kettle twice over.

However, the beams delivered their energy in pulses lasting a little more than 10 billionths of a second.

By way of comparison, if that power could be maintained, it would boil the contents of more than 50 Olympic-sized swimming pools in a second.

'Dramatic step'

Crucially, the recent experiments provided proof that the plasma did not reduce the hohlraum's ability to absorb the incident laser light; it absorbed about 95%.

But more than that, Dr Glenzer's team discovered that the plasma can actually be carefully manipulated to increase the uniformity of the compression.

"For the first time ever in the 50-year journey of laser fusion, these laser-plasma interactions have been shown to be less of a problem than predicted, not more," said Mike Dunne, director of the UK's Central Laser Facility and leader of the European laser fusion effort known as HiPER.

"I can't overstate how dramatic a step that is," he told BBC News. "Many people a year ago were saying the project would be dead by now."

Adding momentum to the ignition quest, Lawrence Livermore National Laboratory announced on Wednesday that, since the Science results were first obtained, the pulse energy record had been smashed again.

They now report an energy of one megaJoule on target - 50% higher than the amount reported in Science.

The current calculations show that about 1.2 megaJoules of energy will be enough for ignition, and currently Nif can run as high as 1.8 megaJoules.

Dr Glenzer said that experiments using slightly larger hohlraums with fusion-ready fuel pellets - including a mix of the hydrogen isotopes deuterium as well as tritium - should begin before May, slowly ramping up to the 1.2 megaJoule mark.

"The bottom line is that we can extrapolate those data to the experiments we are planning this year the results show that we will be able to drive the capsule towards ignition," said Dr Glenzer.

Before those experiments can even begin, however, the target chamber must be prepared with shields that can block the copious neutrons that a fusion reaction would produce.

But Dr Glenzer is confident that with everything in place, ignition is on the horizon.

He added, quite simply, "It's going to happen this year."

[DontSayBanana]

Holy damn; fusion this year would be frikkin' awesome, but I also wonder how long they'll be able to maintain the reaction?

[Viking]

Holy damn; fusion this year would be frikkin' awesome, but I also wonder how long they'll be able to maintain the reaction?

a few milliseconds 

[Grallon]

How much mass would be needed for self sustained reaction?




G.

[DontSayBanana]

How much mass would be needed for self sustained reaction?

G.

I think you're misreading, Grallon.  The point is simply that it might put out more energy than it requires.  It would still need fuel, but I'd assume that past a certain point, the matter required to sustain it would become negligible.  It's been a long time since I've taken physics, though, and I'm not up on the physics of fusion in any case.

[Caliga]

Great, now our future supply of infinite renewable energy has been tainted. 

[Fate]

How much mass would be needed for self sustained reaction?

G.

I think you're misreading, Grallon.  The point is simply that it might put out more energy than it requires.  It would still need fuel, but I'd assume that past a certain point, the matter required to sustain it would become negligible.  It's been a long time since I've taken physics, though, and I'm not up on the physics of fusion in any case.

I think the other advantage of small masses is safety. A miligram or gram sized fusion pellet can't produce a dangerous chain reaction event should anything go wrong.

[jimmy olsen]

Unless I'm mistaken, you can't have a run away reaction with Fusion.

[Fate]

javascript:void(0);
Unless I'm mistaken, you can't have a run away reaction with Fusion.

The article mentioned having to worry about "copious neutron" production from a fusion reaction. Presumably that could cause a chain reaction. 10000 neutrons flying around hit material that subsequently frees up 20000 neutrons, which then hit additional atoms and frees up 40000 neutrons, etc. Although I am not a physicist. 

[The Brain]

javascript:void(0);
Unless I'm mistaken, you can't have a run away reaction with Fusion.

The article mentioned having to worry about "copious neutron" production from a fusion reaction. Presumably that could cause a chain reaction. 10000 neutrons flying around hit material that subsequently frees up 20000 neutrons, which then hit additional atoms and frees up 40000 neutrons, etc. Although I am not a physicist. 

Only if you build the containment out of very inopportune materials. The degradation of the materials from high neutron flux though is a problem.

[Vince]

Frickin laser beams!

Any fusion experiment that doesn't use Superconductors and Pre-sentient Algorithms is doomed to failure.   

[jimmy olsen]

Another successful fusion experiment that happened recently.

http://www.msnbc.msn.com/id/35126008/ns/technology_and_science-science/

Levitating magnet coaxes nuclear fusion
Energy could be created by fusion without any greenhouse gas emissions

By Clara Moskowitz
updated 12:34 p.m. ET Jan. 28, 2010

Physicists may be one step closer to achieving a form of clean energy known as nuclear fusion, which is what happens deep inside the cores of stars.

A recent experiment with a giant levitating magnet was able to coax matter in the lab to extremely high densities — a necessary step for nuclear fusion.

When the density is high enough, atomic nuclei — the protons and neutrons of atoms — literally fuse together, creating a heavier element. And if the conditions are right that fusion can release loads of energy.

Depending on the mass of this element, energy could be created by fusion without any greenhouse gas emissions. So it could present a tantalizing clean power source, if scientists could achieve it.

"Fusion energy could provide a long-term solution to the planet's energy needs without contributing to global warming," said Columbia University physicist Michael Mauel, co-leader of the recent study.

Such a power source would produce far less radioactive waste than current nuclear energy plants, which involve splitting atoms apart — called fission — the opposite of fusion.

For the new study scientists built a Levitated Dipole Experiment, or LDX, which involves suspending a giant donut-shaped magnet in midair using an electromagnetic field.

The magnet weighs about a half-ton, and is made of superconducting wire coiled inside a stainless steel container about the size and shape of a large truck tire. The researchers used the magnet to control the motion of an extremely hot gas of charged particles, called a plasma, contained within its outer chamber.

The doughnut-shaped magnet creates a turbulence that causes the plasma to condense, instead of becoming more spread out, as usually happens with turbulence. Such "turbulent pinching" has been observed with space plasma in the magnetic fields of Earth and Jupiter, but never before in the lab.

The approach "could produce an alternative path to fusion," said co-leader Jay Kesner of MIT, but to reach the density levels needed for commercial fusion, scientists would have to build a much larger version of the experiment.

A key to the device is the fact that the LDX magnet is levitating, rather than suspended by any struts, because the magnetic field used to confine the plasma would be disturbed by any objects in its way.

In the experiment, the doughnut magnet was held aloft by a magnetic field from an electromagnet overhead, which is controlled by a computer based on readings from laser beam sensors. This set-up can adjust the position of the giant magnet to within half a millimeter.

Just in case the magnetic levitating system fails, the experiment included a cone-shaped support with springs underneath the magnet to catch it if need be.

The researchers detailed their findings this week in the journal Nature Physics.
© 2010 LiveScience.com. All rights reserved.

[The Brain]

Star Trek technobabble.

[Jaron]

All we need now is to find a mine with naturally occurring dilithium crystals..

[Josquius]

Unless I'm mistaken, you can't have a run away reaction with Fusion.

I definatly remember something about the reacion just all fizzling away if the containment field drops.