Fusion Power Near?

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Experiments at the National Ignition Facility have given researchers confidence that they'll achieve a milestone in nuclear fusion sometime this year.

The tests involved blasting a cylinder the size of a pencil eraser, known as a "hohlraum," with 192 laser beams and seeing whether researchers could tweak the energy to create the right kind of implosion.

The results suggested that they could - and that the $3.5 billion blaster in California just might produce the world's first controlled fusion reaction, with more energy coming out than going in.

For more than a half-century, scientists have been trying to harness the nuclear fusion reaction to generate what could be prodigious amounts of energy. The reaction involves crushing together light atoms (like hydrogen) so forcefully that they fuse into heavier atoms (like helium). Each reaction converts a tiny amount of mass from the atoms directly into energy.

When you multiply that demonstration of E=mc2 by trillions, you start producing power on the scale of an H-bomb or the sun.

The research reported by the National Ignition Facility, or NIF, represents a step toward actual energy production in a controlled reaction. But there are still many steps to go before scientists reach that break-even point. Even if NIF is successful, it will take years to adapt the technology for commercial applications. And that's the most optimistic view.

Jeffrey Atherton, the program director for target experimental systems at NIF, is an optimist.

"The potential for NIF and fusion energy as the game-changer [for energy resources] is enormous," he told me. He acknowledged that commercial fusion was far from a sure bet, but said the technology had to be included in the nation's portfolio of energy research. "You have to invest in things that could have risk associated with them, but also have enormous benefits should they play out," Atherton said.

The initial tests at NIF, built at the Lawrence Livermore National Laboratory in Northern California, have made Atherton and his colleagues feel more comfortable about the investment. Those tests are detailed today in a research paper published online by the journal Science.

"When we extrapolate the results of the initial experiments to higher-energy shots on full-sized hohlraums, we feel we will be able to create the necessary hohlraum conditions to drive an implosion to ignition later this year," Siegfried Glenzer, plasma physics group leader at Lawrence Livermore National Laboratory, told me in an e-mail.

What's a hohlraum?

The term "hohlraum" comes from the German words for "hollow area." Hohlraums are hollow, gold-plated cylinders that are structured to spread the energy from the laser beams into a inward-pointing blast of X-rays, all focused on a target the size of a small pea. The target is a precisely machined, spherical pellet of beryllium, containing the stuff to be imploded.

For the real ignition shots, the targets will be filled with a cryogenically cooled dollop of deuterium-tritium fusion fuel. Deuterium and tritium are two isotopes of hydrogen that are particularly well-suited for fusion. If the researchers do it right, that tiny bit of fuel would be compressed by a factor of 1,000 or more, and reach temperatures approaching 100 million degrees Celsius (180 million degrees Fahrenheit). That's hotter than the sun.

For the tests described in the Science paper, the hohlraums were smaller, the targets were filled with plain old hydrogen and helium, and the temperatures reached a mere 3.3 million degrees C (6 million degrees F). The resulting reaction fell far short of break-even fusion, but Atherton said it confirmed that NIF was on the right track.

"The point is that we were doing it at a scale that's about 20 times larger than has been done, with a laser power that accordingly is about 20 times higher than has been done, with a precision and efficiency that hasn't been done before," he said.

Dealing with uncertainty

One big challenge was to aim the laser beams so precisely that the target was heated evenly. If the heating is the slightest bit uneven, the fusion fuel will splurt away before it implodes enough to create the pressure and temperature required for ignition. That's essentially what happened at NIF's predecessor, the $200 million Nova laser facility. But researchers said they were satisfied with the uniformity of heating at NIF.

"We also demonstrated a very elegant way of tuning the symmetry of the laser beams, by making very subtle changes in the color of the wavelength in the cone of these beams," Atherton said.
Glenzer told me the wavelength-tuning trick "was predicted to work, but could only be tested on full NIF experiments described in this paper." More than 90 percent of the laser energy was absorbed by the hohlraums - which is more than was predicted by the pre-test simulations.

The experiments demonstrated that researchers could "overcome the biggest physics uncertainty in laser fusion - namely, we showed that we can heat hohlraums to temperature and radiation symmetry close to what is needed for ignition," Glenzer said.

Atherton echoed those comments in more down-to-earth terms: "Given the very positive results out of last summer and fall, we do feel much more confident about the feasibility of fusion as an energy source," he told me.

The tests described in Science were conducted last year at an energy level of 0.7 megajoules. Since then, NIF has ramped up to the 1-megajoule level, and Atherton said "our ignition experiments will be operating at a laser energy of 1.2 or 1.3 megajoules this summer."

Energy source of the future?

The results impressed other experts. "They're ahead of the curve predicted," Mike Dunne, director of the Central Laser Facility of Britain's Rutherford Appleton Laboratory, told Science.

"It's definitely a very capable and interesting machine," said Charles Seife, a longtime science writer and journalism professor at New York University who wrote a book about the fusion quest titled "Sun in a Bottle."

However, it remains to be seen whether reality will follow the predicted path. In his book, Seife shows that the course of true fusion never did run smooth, despite repeated predictions that success was just a few years and a few (million? billion?) dollars away. The classic joke is that fusion is the "energy source of the future - and always will be."

Even Atherton acknowledges that NIF's nanosecond-long shots can't be harnessed for commercial purposes in the near term. The shots would have to occur "10 times per second, as opposed to once every few hours, or days, or pick your unit of time," he said.

Researchers say NIF could blaze a trail for more commercially viable concepts. For example, the Laser Inertial Fusion Engine, or LIFE, would use laser shots to generate neutrons for a hybrid fusion-fission reaction.

However, in the long run, it may turn out that one of the other approaches to fusion will be more fruitful. Maybe it'll be the $13 billion magnet-based ITER project taking shape in France. There are also a number of dark-horse candidates - such as the low-cost, high-voltage system currently being funded by the Navy, or the levitating-magnet system that came into the spotlight just this week.

Atherton said NIF would almost certainly be the first technology to reach the break-even point - but he said it made sense to investigate other paths to fusion as well. "We don't look at this as a competition, as much as that we're all in a race to develop clean energy resources," he said. He recognized that other energy technologies - including biofuels, solar, wind and safer fission reactors - also had to be funded.

"Many people who study this and try to take a considered, balanced perspective actually believe that it's important to invest in all of these technologies," Atherton said.

Beyond energy production

Atherton pointed out that fusion research isn't aimed exclusively at commercial energy production. The knowledge gained at NIF could also be applied to astrophysics and nuclear physics - that is, the science behind what happens in stars. "There's a whole wealth of basic science that could be done with this type of burning-plasma creation," he said. "That could give physicists the ability of doing experiments looking inward instead of outward."

There's yet another big reason why the U.S. Department of Energy has spent billions of dollars on NIF: "The physical conditions created with an ignition-type target can be used to study important physics questions related to the safety and reliability of the nuclear stockpile," Atherton said.

Seife suspects that the weapons issue is the key to NIF's existence, but he hasn't been able to put his finger on how exactly the research being conducted there benefits the U.S. nuclear weapons program. He wonders whether NIF is actually less about nuclear physics - and more about keeping nuclear physicists employed.

"NIF isn't truly about energy," Seife writes in his book. "It is not about keeping our stockpile safe, at least not directly. It is about keeping the United States' weapons community going in the absence of nuclear tests."

Is NIF on the right track for nuclear fusion? Is the promise of nearly limitless energy worth the billions of dollars being spent on fusion research? Or is fusion research really a matter of national security rather than energy production? Feel free to weigh in with your comments below.

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Source

Still don't have my jetpack, though.

It was mentioned in the other article, so for completeness, levitating magnetic fusion:

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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.

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I beg pardon here, but would so much energy going through these machines make them more dangerous or prone to largescale disasters should something go horribly wrong?

I'm really hoping that fusion comes about in my lifetime.
Limitless energy rocks hard.

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Originally Posted by Supermarioman

I'm really hoping that fusion comes about in my lifetime.
Limitless energy rocks hard.

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There is no such thing as limitless energy.

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Originally Posted by Being

There is no such thing as limitless energy.

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That's a technicality.
By the time we run out, Humanity is dead anyway from a solar flare or something.

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Originally Posted by Wraith

Still don't have my jetpack, though.

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However you're now that much closer to having a fusion powered jetpack...:o

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Originally Posted by coinich

I beg pardon here, but would so much energy going through these machines make them more dangerous or prone to largescale disasters should something go horribly wrong?

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No. It would have about the same results as the turbine in a coal plant exploding. The difference between fusion and fission is that the latter can be self-sustaining, thus subject to runaway processes. With fusion, once you remove the exciter, you effectively stop fusion.

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The results suggested that they could - and that the $3.5 billion blaster in California just might produce the world's first controlled fusion reaction, with more energy coming out than going in.

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Not true, JET can already produce more energy than it consumes, and has proven that (in a tokomak set-up).

Laser induced fusion is, while very interesting, not really suitable for energy production. As it stands, the most promising option is a magnetically confined plasma in a tokamak. Last time I checked, the outlook is that a tokamak style commercial prototype can be built in the 2030s, which means that one or two decades later they can be built commercially.

I'll know more in a short while though, Starting Wednesday I have a class on 'routes to fusion power' with a leading professor in the field :) Should be interesting.

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Originally Posted by coinich

I beg pardon here, but would so much energy going through these machines make them more dangerous or prone to largescale disasters should something go horribly wrong?

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Not really. Fusion isn't a self-sustaining process (like fission power plants), so if something goes wrong the reactor will be ruined, but there won't be a large-scale disaster.

"tokamak"

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Originally Posted by Nessus

"tokamak"

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Fixed. Firefox dictionary didn't know it :(

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Originally Posted by Flixy

Not true, JET can already produce more energy than it consumes, and has proven that (in a tokomak set-up).

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Sustained and controllable? That's the milestone I thought hadn't been reached yet. We've been able to make fusion reactions that produce more energy than they consume since the '50s or so.

edit: I did a bit of digging, and the latest I can find is that JET thinks they can cause a reaction that produces more energy than is used in heating, but it was only based on estimates and has never been verified in real conditions, and wouldn't take care of the energy used for containment anyways. This isn't totally current though, so throw a source at me if you know of anything better.

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Originally Posted by Wraith

Sustained and controllable? That's the milestone I thought hadn't been reached yet. We've been able to make fusion reactions that produce more energy than they consume since the '50s or so.

edit: I did a bit of digging, and the latest I can find is that JET thinks they can cause a reaction that produces more energy than is used in heating, but it was only based on estimates and has never been verified in real conditions, and wouldn't take care of the energy used for containment anyways. This isn't totally current though, so throw a source at me if you know of anything better.

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Define sustained and controllable? They managed to control a plasma in the reactor for a few seconds, seems sustained and controllable to me.

And this experiment uses laser pulses right? That doesn't sound very sustained to me.

Im checking for sources and will get back to you.

Okay, I looked it up, and you're right. Their record is a factor of 0.7 between input and output energy. They do have the record for 16 MW of power. Tokamaks improve with size, so ITER should pass it with ease.

If you want to read up on the commercial outlook for fusion plants:

http://www.efda.org/eu_fusion_progra...th_annexes.pdf

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Researchers say NIF could blaze a trail for more commercially viable concepts. For example, the Laser Inertial Fusion Engine, or LIFE, would use laser shots to generate neutrons for a hybrid fusion-fission reaction.

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Hybrid fusion/fission still has nuclear waste.

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Originally Posted by Flixy

Define sustained and controllable?

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Sustained means they can keep it going. Controllable means they can stop it before they explode.

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And this experiment uses laser pulses right? That doesn't sound very sustained to me.

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Lasers can be fired more than once. :|

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Im checking for sources and will get back to you.

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Found something. Should have checked here more thoroughly the first time I looked, but I gave up too easy. JET themselves claim they've never been able to exceed the heating power requirements alone, and that still leaves out the containment power that keeps it controllable.

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Originally Posted by Flixy

Hybrid fusion/fission still has nuclear waste.

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Wait, are you only in here because you're offended that some dirty Americans might succeed before ITER?

Both can be self sustaining. It's all about the specific environment.

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Originally Posted by Wraith

Sustained means they can keep it going. Controllable means they can stop it before they explode.

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Actually, it's "before the reaction breaks down and has to be reinitialized".

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Originally Posted by Wraith

Sustained means they can keep it going. Controllable means they can stop it before they explode.

Lasers can be fired more than once. :|

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Yeah but it's a pulsed process. At least with the current setup it is not sustained.

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Found something. Should have checked here more thoroughly the first time I looked, but I gave up too easy. JET themselves claim they've never been able to exceed the heating power requirements alone, and that still leaves out the containment power that keeps it controllable.

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Yeah, I looked it up too, like I posted right before you.. Still a hell of a lot better than the laser efficiency, especially if you include poor efficiencies of lasers. I think I read about a new way of laser induced fusion that has a possibility for much higher efficiencies, but IIRC it hasn't been tested yet.

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Wait, are you only in here because you're offended that some dirty Americans might succeed before ITER?

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No, what would make you think that? :s

For starters, USA is part of the ITER project.

I just think that tokamaks are much more feasible for power generation in the near future, and that this thread is a bit too optimistic about this technique. It is very interesting, very useful in a lot of things, but not really suitable (not as it is now, anyway) for power production, and that's what your thread title is about.

Or are these all anti-American views, too? :bulb:

Tokamas have always seemed a somewhat silly idea to me, trying to confine your reaction by keeping it moving in an absurd toroidal-helix adds many difficulties to the equation.

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Originally Posted by Flixy

Yeah but it's a pulsed process. At least with the current setup it is not sustained.

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I think it still counts if it works like a gasoline engine. They can't fire the lasers fast enough yet, but that's just a scaling problem.

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Yeah, I looked it up too, like I posted right before you.. Still a hell of a lot better than the laser efficiency, especially if you include poor efficiencies of lasers. I think I read about a new way of laser induced fusion that has a possibility for much higher efficiencies, but IIRC it hasn't been tested yet.

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The article is about the scientists thinking they can pass the break even point this year, which would be undeniably better efficiency. Didn't spot an exact efficiency level in the article and too lazy to look for one, but they're looking at a level of energy input far less that what JET uses.

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No, what would make you think that? :s

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The constant attempts to find ways that it doesn't count, and just knowing you.

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Originally Posted by Wraith

I think it still counts if it works like a gasoline engine. They can't fire the lasers fast enough yet, but that's just a scaling problem.

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That is more than jsut a scaling problem.

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The article is about the scientists thinking they can pass the break even point this year, which would be undeniably better efficiency. Didn't spot an exact efficiency level in the article and too lazy to look for one, but they're looking at a level of energy input far less that what JET uses.

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It is a milestone, yes, but also a lower energy outputs by the way. And the entire process used in this experiment is just not suitable for power production. The actual efficiency of the overall process is still well below 10%, by the way.

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The constant attempts to find ways that it doesn't count, and just knowing you.

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I suggest yuo get to know me better then.

These 'constant attempts to find ways that it doesn't count', are they realyl wrong if they go against your claim that this is suitable for energy production? Because it isn't, and it isn't meant for it. The NIF program is based on nuclear weapons research, just like their French counterpart. This type of laser driven fusion would need to improve ~300 times to become a feasable power source, and that is assuming they can easily take energy from the reactor, which is also a big problem. It is very useful to look at fusion physics, and for weapons research. I am not saying this research doesn't count, and it is an impressive milestone, but it isn't aimed at power production.

I'm very sorry if criticising your thread title has somehow stepped on your nationalist toes or something? But I didn't even really know/care that this project was American. You suddenly brought up that I am defending our 'European pride' by saying another project is much more promising for power production - a project that actually has the Americans as a major party. And Russia, China, India, Japan and Korea. EU isn't even a majority partner AFAIK. You're just paranoid, man. If anything, I dislike nationalist involvement in science. The debate of where to place an installation delays the project, and the jobs per country quota mean that not necessarily the best people are on the jobs, but the people with the right nationalities, which is never a good thing.

Besides, if I wanted to talk down this project because it is American, I could simply talk about HiPER, which is laser driven, European, and expected to be about 100 times more efficient.

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Originally Posted by Illusions

However you're now that much closer to having a fusion powered jetpack...:o

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Jet packs are over-rated. Flying one around is like riding a motorcycle only worse. Yes, motorcycles are fun but how many do you see riding around on a rainy day? Or in the winter? You're just too exposed; useless for commuting....

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Originally Posted by Khendraja'aro

No. It would have about the same results as the turbine in a coal plant exploding. The difference between fusion and fission is that the latter can be self-sustaining, thus subject to runaway processes. With fusion, once you remove the exciter, you effectively stop fusion.

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With such gigantic energy input required, it seems if there was some major disaster that shut the plant down, restarting it might be a trick.

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Originally Posted by Wraith

Sustained and controllable? That's the milestone I thought hadn't been reached yet. We've been able to make fusion reactions that produce more energy than they consume since the '50s or so.

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Heh heh, fusion bombs produce lots more energy than you put in. :downcast:

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Originally Posted by Flixy

That is more than jsut a scaling problem.

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Do the same thing, but more often. :shrug:

{edit: Further reading suggests that they believe they can keep it going without refiring the lasers if desired. After ignition they they can make it steady-state with a fusion/fission reaction. Only the pure fusion approach needs to refire lasers.}

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It is a milestone, yes, but also a lower energy outputs by the way. And the entire process used in this experiment is just not suitable for power production. The actual efficiency of the overall process is still well below 10%, by the way.

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The only number I saw was that it was able to achieve a better-than-expected 90% efficiency with getting energy from the lasers into the hohlraum. While talking about efficiency, you're still ignoring that they expect to get more than 100% of the input energy back out this year. I don't know how that could count as overall poor efficiency, at least not relative to the rest of the projects, since they'll be the first.

{edit: Further reading gives the expected number of 40 MJ of output for 1.4 MJ of input being expected this year or early next. First attempts to reach this will be made this summer. They will then scale it up to 200 MJ, it's unclear if the input will also scale. The experts who are working on this believe this technology will be producing a few hundred MW in the not-too-distant future, and then commercial applications can scale it to a 2000-3000 MW.}

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I suggest yuo get to know me better then.

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Nah, I think I'm doing alright. I of course never dreamed that you'd admit to anything, but this passive-aggresive superpatriotism is par for the course. I even expected you to try that silly attempt at turning it around on me. You keep trying to play it all down, find ways it doesn't count, saying I should take your word over the experts who actually know what's going on. At least start providing sources. I don't claim to be an expert, and I'm open to the idea that there are even better efforts out there.

Also, "isn't aimed only at power production".

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Besides, if I wanted to talk down this project because it is American, I could simply talk about HiPER, which is laser driven, European, and expected to be about 100 times more efficient.

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But you did try that, with JET. It just turned out to be a poor attack. Are you trying to open the door for another attempt?

{edit: Read up on HiPER. From their numbers, they're expecting about 81% the efficiency that NIF is expecting. These are expectations only though, and given the uncertainty probably close enough they can be considered roughly equal. But HiPER is also looking at a tiny fraction of the scale of NIF. NIF is expecting output in MJ, and HiPER in KJ. HiPER is going at things from a slightly different angle than NIF, so its work is still potentially valuable.}

You're jokeposting, right?

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Originally Posted by Flixy

I'll know more in a short while though, Starting Wednesday I have a class on 'routes to fusion power' with a leading professor in the field :) Should be interesting.

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I'd be really interested in hearing about anything you go over in this class. Even just some references!

Sorry for the late reply but:

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Originally Posted by Wraith

Do the same thing, but more often. :shrug:

{edit: Further reading suggests that they believe they can keep it going without refiring the lasers if desired. After ignition they they can make it steady-state with a fusion/fission reaction. Only the pure fusion approach needs to refire lasers.}

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Where did you get your further reading? Because the entire process revolves around a discardable pellet which is lit up with the lasers. It burns out quickly. How on earth can you keep that going? =\

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The only number I saw was that it was able to achieve a better-than-expected 90% efficiency with getting energy from the lasers into the hohlraum. While talking about efficiency, you're still ignoring that they expect to get more than 100% of the input energy back out this year. I don't know how that could count as overall poor efficiency, at least not relative to the rest of the projects, since they'll be the first.

{edit: Further reading gives the expected number of 40 MJ of output for 1.4 MJ of input being expected this year or early next. First attempts to reach this will be made this summer. They will then scale it up to 200 MJ, it's unclear if the input will also scale. The experts who are working on this believe this technology will be producing a few hundred MW in the not-too-distant future, and then commercial applications can scale it to a 2000-3000 MW.}

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With overall I meant including the efficiency of the lasers, which is low, and is insanely low if you count the energy you need to calibrate it.

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Nah, I think I'm doing alright. I of course never dreamed that you'd admit to anything, but this passive-aggresive superpatriotism is par for the course. I even expected you to try that silly attempt at turning it around on me. You keep trying to play it all down, find ways it doesn't count, saying I should take your word over the experts who actually know what's going on. At least start providing sources. I don't claim to be an expert, and I'm open to the idea that there are even better efforts out there.

Also, "isn't aimed only at power production".

But you did try that, with JET. It just turned out to be a poor attack. Are you trying to open the door for another attempt?

{edit: Read up on HiPER. From their numbers, they're expecting about 81% the efficiency that NIF is expecting. These are expectations only though, and given the uncertainty probably close enough they can be considered roughly equal. But HiPER is also looking at a tiny fraction of the scale of NIF. NIF is expecting output in MJ, and HiPER in KJ. HiPER is going at things from a slightly different angle than NIF, so its work is still potentially valuable.}

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A couple of things.

I'm not saying NIF work isn't valuable. It is very valuable, and they have reached an important step.

My issue is with the fact that you claim to that NIF gets us close towards (commercial) power production with fusion. All I'm saying is that it isn't. Nothing to do with any anti-Americanism, which is retarded to claim to say the least, because ITER involves the USA too, AFAIK with similar budgets. It seems you are mixing up things and you don't really seem to know what you are talking about.


The setup at NIF basically works by firing a LOT of laser power into a small gold pallet which contains a tiny drop of deuterium-tritium mixture. The gold pellet is lit up by the short laser pulse, and emits a lot of X-rays which in turn heat up the D-T droplet, very symmetrically, turning it into a plasma. The entire thing is in a vacuum chamber, because otherwise you won't be able to get your lasers on target this accurately. After the explosion, which caused actual 'ignition' of the plasma (I think that's a world's first, too), the thing needs to cool off, replace the pallet and re-align the lasers.

There are quite a lot of problems with using this as a power source though.
- The laser system is tricky as hell (and that's an understatement) to align. A full power shot requires a few months to align and build up. The laser system is a couple of football fields big, and IIRC ten stories high. Not to mention extremely expensive. Lasers are already pretty energy consuming, and considering you need them on for long times for one shot, that fucks up your overall energy efficiencies.
- Replacing the pallet. The inside of the vacuum chamber becomes radioactive from the gold pallet causes the vacuum chamber to become radioactive. This isn't a problem now, since there is a few months between full power shots anyway, but if you want to every few seconds that IS a problem. And there is the issue that the evaporated gold ruins your vacuum, and deposits on the chamber. The pallet is also fairly expensive to build (~tens of thousands USD) although that will drop with mass production, but the gold it requires will never make them really cheap.
- Getting energy out. To get energy out, you'd want something around it to absorb the energy, but since you have to get laser power in from all sides, simultaneously, you can't.
- Scaling. You can't just make the pellets bigger. If they get bigger, uniformity of the laser and X-ray power is harder to achieve, and the pressure in the droplet decreases, decreasing the fusion process. But I might be wrong on that.

Overall the system is designed to get high energies in small confined spaces. This is useful for elementary research, and for weapon research. It can be used to simulate the effects of hydrogen bombs, which is very useful since testing them for real is banned. You are aware where the funding of NIF came from? Hint: it's not an energy-production fund.

Maybe some, or even all of these problems can be solved at some point, but it's not very likely and especially not any time soon.



So why do I think that magnetically confined fusion is a more likely option, especially in the short term?

Mostly because it's far closer. It's tricky to confine a plasma, but it is shown to be manageable. Ways to get energy in and out have been tested and designed and are feasible, which has yet to be shown for laser ignition. Efficiencies also increase with size (opposite for laser ignition). The outlines for a blueprint of a commercial plant have been made. ITER will provide a wealth of information about containing and controlling bigger fusion reactions and testing materials (to withstand neutron bombardments), which can then be incorporated in the demonstration model of a commercial plant. This is already mapped out and planned (see DEMO). Basically, commercial fusion power generation by magnetic confinement is two generations away, three to actual use. Commercial fusion power generation by laser ignition, well, we don't even know how far it is away, nor are there any concrete plans for it as far as I know. It's still very much in the initial research stage. Maybe this type of fusion power source will become feasible, and more efficient or cheaper than magnetic confinement, but I can assure you it won't be the first one to be built commercially, unless something very unexpected happens.


Hope you can read this as a substantial opinion, based on facts, and not as a knee jerk reaction to your post. Or superpatriotism or whatever. You could maybe 'expect' me to turn it around, but let's face it, you are defending this NIF thing more than you should, really. By the way, I don't have sources for this beyond a reader that isn't online and a chat with a professor and a post-doc (who actually worked at NIF...) who are both working in the field.

By the way, HiPER aims for a kJ input but an output similar to NIF, which would make it more efficient. Not surprising, since they use a different process that builds on knowledge gained by, among others, the NIF. I mean, comon, it's in the first paragraph on wikipedia: http://en.wikipedia.org/wiki/HiPER

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Originally Posted by Flixy

Where did you get your further reading? Because the entire process revolves around a discardable pellet which is lit up with the lasers. It burns out quickly. How on earth can you keep that going? =\

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From NIF. The link I gave you back when we were first going on this. How does your car engine keep on going? You keep injecting more fuel, the process continues.

You can get a lot of information starting at this page and following it out from there. There's a lot of information around there, and some of the pages are a bit out of date, but it gives a good overview of the project and where they expect to take it.

Anyone want to take bets on how selective Flixy's reading will be? It's not ready now, there are still issues to solve, but it also shows good promise to be a commercially viable means of energy production. Why are you so intent on denying this?

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With overall I meant including the efficiency of the lasers, which is low, and is insanely low if you count the energy you need to calibrate it.

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They're expecting energy positive looking at the entire system. If you want to continue insisting that the nuclear physicists working on this and similar projects are all wrong, then I don't see how this can continue. I'm never going to take your word over that of the experts actually involved in the project.

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My issue is with the fact that you claim to that NIF gets us close towards (commercial) power production with fusion. All I'm saying is that it isn't. Nothing to do with any anti-Americanism, which is retarded to claim to say the least, because ITER involves the USA too, AFAIK with similar budgets. It seems you are mixing up things and you don't really seem to know what you are talking about.

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Are you sure it's me? You keep tossing out things that are in contradiction with the existing literature, then you try to move on to the next attempt at an attack like nothing happened, and that none of the facts actually count.

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The setup at NIF basically works by firing a LOT of laser power into a small gold pallet which contains a tiny drop of deuterium-tritium mixture. The gold pellet is lit up by the short laser pulse, and emits a lot of X-rays which in turn heat up the D-T droplet, very symmetrically, turning it into a plasma.

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It's not a gold pellet they're looking at right now, the D-T is in a pellet - is that what you mean? There's gold in the hohlraum, if that's what you mean, but it's unlike the either a pallet or pellet (you were inconsistent). The fuel pellet itself is supposed to be made of either beryllium or plastic, IIRC, with a juicy hydrogen core.

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The entire thing is in a vacuum chamber, because otherwise you won't be able to get your lasers on target this accurately. After the explosion, which caused actual 'ignition' of the plasma (I think that's a world's first, too), the thing needs to cool off, replace the pallet and re-align the lasers.

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They haven't actually run this experiment with a real fuel target yet AFAIK, only a dummy target that wouldn't ignite. The first real attempt is scheduled for this summer. This was the proof-of-concept, which proved that all the mechanics work, and they can hit the targets reliably in all the ways that matter.

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- The laser system is tricky as hell (and that's an understatement) to align. A full power shot requires a few months to align and build up. The laser system is a couple of football fields big, and IIRC ten stories high. Not to mention extremely expensive. Lasers are already pretty energy consuming, and considering you need them on for long times for one shot, that fucks up your overall energy efficiencies.

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Yet they've proven they can have everything ready faster than that - they can fire every several hours now with the laser systems they're using in the project currently, and ten times a second with lasers they're developing to replace them (the later aren't powerful enough to work for fusion yet). Their biggest limitation right now is how fast the lasers can actually fire rather than any targeting issues, and that's an issue that's been mostly dealt with - they know how to solve it.

They have a laser system that can be fired 10 times per second. It's not integrated with their fusion project, and IIRC it still needs to have its power output scaled up before it can be, but all the components they need for their system either already exist or shouldn't be too long in coming. This is one of its advantages over ITER - the components can be developed and tested seperately, and more cheaply.

I'll give you an out here - earlier, the alignment and targetting did threaten to be a showstopper, even though many didn't think it would be, and it's only last year that it was proven that it's not. This was done fairly recently, so you might still just be going off of slightly older information.

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- Replacing the pallet. The inside of the vacuum chamber becomes radioactive from the gold pallet causes the vacuum chamber to become radioactive. This isn't a problem now, since there is a few months between full power shots anyway, but if you want to every few seconds that IS a problem. And there is the issue that the evaporated gold ruins your vacuum, and deposits on the chamber. The pallet is also fairly expensive to build (~tens of thousands USD) although that will drop with mass production, but the gold it requires will never make them really cheap.

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I think you're confusing the hohlraum with the fuel pellet - it's hard to tell which you're refering to. The system to inject fuel targets isn't a very complicated problem compared to the rest. We have plenty of existing systems that do similar jobs tens or hundreds of times per second.

They're trying to get fuel production down to 25 cents or less per, and have some submitted designs from external agencies for factories that can approach this goal.

This study concludes that fuel costs can be dropped down to commercially viable levels with mass manufacturing, with the possibility to lower it further as research continues.

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- Getting energy out. To get energy out, you'd want something around it to absorb the energy, but since you have to get laser power in from all sides, simultaneously, you can't.

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You don't need to put energy in at the same time and place as you take it out. This problem is faced by all forms of fusion power anyways, and not a particularly hard one. Where you have an energy differential, extracting energy isn't very difficult. Several options already exist.

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- Scaling. You can't just make the pellets bigger. If they get bigger, uniformity of the laser and X-ray power is harder to achieve, and the pressure in the droplet decreases, decreasing the fusion process. But I might be wrong on that.

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I'm not clear on what their plans to scale it are, but the nuclear physicists seem confident that this can be scaled up to a 2000-3000 MW generator commercially. Once the point where scaling is too difficult is reached, you can keep going just by increasing the number of generators per plant. There's good room for minaturization here too.

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Overall the system is designed to get high energies in small confined spaces. This is useful for elementary research, and for weapon research. It can be used to simulate the effects of hydrogen bombs, which is very useful since testing them for real is banned. You are aware where the funding of NIF came from? Hint: it's not an energy-production fund.

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You keep desperately going back to that as if it proves something, and sure they're working on nuclear technology, astrophysics, laser research at NIF too, but this particular project has as it's goal a commercially viable means of energy production with fusion. All their projects complement each other. That they're also running projects that don't have the goal of energy production scores you no points.

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Maybe some, or even all of these problems can be solved at some point, but it's not very likely and especially not any time soon.

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The worst problems seem to be pretty much solved. The burn this summer, if successful, will serve as proof of that. That's not to say that eveything is solved, natch. I'm not predicting the fusion power tomorrow, or even next year, or even this decade.

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Mostly because it's far closer. It's tricky to confine a plasma, but it is shown to be manageable. Ways to get energy in and out have been tested and designed and are feasible, which has yet to be shown for laser ignition. Efficiencies also increase with size (opposite for laser ignition). The outlines for a blueprint of a commercial plant have been made. ITER will provide a wealth of information about containing and controlling bigger fusion reactions and testing materials (to withstand neutron bombardments), which can then be incorporated in the demonstration model of a commercial plant. This is already mapped out and planned (see DEMO). Basically, commercial fusion power generation by magnetic confinement is two generations away, three to actual use. Commercial fusion power generation by laser ignition, well, we don't even know how far it is away, nor are there any concrete plans for it as far as I know. It's still very much in the initial research stage. Maybe this type of fusion power source will become feasible, and more efficient or cheaper than magnetic confinement, but I can assure you it won't be the first one to be built commercially, unless something very unexpected happens.

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I won't try to assure you that you're wrong, because that remains to be seen - the tests this year will probably be a good time to decide if it is. ITER is nice, but goddamn is it slow in going. All the politics surrounding it seems to be slowing it down and reducing its promise. When started, ITER was the best hope, but lately it seems more and more like a fall-back option if none of the other ideas work out. ITER has the promise that we might be able to start on the first commercial fusion reactor in 30 years (probably more, given the history of the project), but if the LIFE project pans out, we can start looking at building a commercial fusion reactor a bit sooner, and more cheaply. That's not a certainty yet - some of the other possibile candidates out there might even be able to beat the LIFE approach.

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Hope you can read this as a substantial opinion, based on facts, and not as a knee jerk reaction to your post. Or superpatriotism or whatever. You could maybe 'expect' me to turn it around, but let's face it, you are defending this NIF thing more than you should, really.

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Only because I was provoked. I don't give a shit about who solves the problem, I just want it solved as soon as possible and to make sure we didn't exclude potentially better approaches.

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By the way, HiPER aims for a kJ input but an output similar to NIF, which would make it more efficient. Not surprising, since they use a different process that builds on knowledge gained by, among others, the NIF. I mean, comon, it's in the first paragraph on wikipedia: http://en.wikipedia.org/wiki/HiPER

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Called it.

Wikifist, but you should read it more carefully. They're not looking at a similar output, not even close. They're looking at 3 kJ in, 70 kJ out for ignition IIRC, compared with 1.4 MJ in, 40 MJ out for NIF. They're hoping to eventually see a higher percentage gain than the current NIF research - HiPER is skipping straight to fast-ignition, something that NIF isn't going to try to seriously get working until they get the current system working - it's why HiPER is valuable. If HiPER works out, it could knock another few years off the time until we get to fusion power.

As an apology - rereading my last edit on my previous post, it sounds like I was suggesting you read up on the project, but I meant the past-tense "read" rhymes with "red" with the implied subject "I".