Fusion laser, a bomb?

Seems the government started construction of a super fusion laser over a decade ago, and through a series of budget cuts and cost overruns, they're still working on it. 5 billion dollars later, and still 5 years to go.

Initially designed to test the quality of nuclear arms without wasting any weapons, scientists are now suggesting the NIF laser can achieve solar ignition as early as 2010. But if they do manage to produce the sun's energy here on Earth, will we be able to extinguish it before it consumes the planet?

http://news.yahoo.com/s/ap/20050521/ap_on_sc/super_laser

Edit: Planet consumption is not covered in the above article. /ubbthreads/images/graemlins/tongue.gif

project with so much cost overruns and our severe bugdet deficit does not look very promising. congess will can it once the republicans lose the majority and when bush leaves office, but if it does come to fruition, let's do a group buy on this "unloveble laser". /ubbthreads/images/graemlins/grin.gif

Politically challenged are we? /ubbthreads/images/graemlins/rolleyes.gif

phobic arent we?

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will we be able to extinguish it before it consumes the planet

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I skimmed the article, I couldn't find this little tidbit in it, is this just your own joke? /ubbthreads/images/graemlins/smile.gif Cause if they printed that it's got to be the most ridiculous thing I've ever seen /ubbthreads/images/graemlins/grin.gif

That facility cannot and was not designed to produce a sustained reaction. it's a one shot deal inside a containment vessel designed to hold the output from the one shot. You're not in any danger from this experiment. You really need to put smilies at the end of straight lines like that /ubbthreads/images/graemlins/grin.gif

comments to senecaripple self moderated out as inapplicable to the discussion at hand

And congress won't cancel it as it's for studying how our bombs will work as they continue to degrade. They are very concerned about that sort of thing. Without the ability to test them, the more we learn about this stuff the better our computer models will be for figuring out how the current stash of Bombs will work if we ever had to do them. IT's still a deterrent if we're more sure than the next guy that ours will actually go off...

you americans should be very carefull whith this kind of experiments cause they're likely to create mini black holes that could grow bigger and bigger finishing by the swallow up of the whole solar system /ubbthreads/images/graemlins/mecry.gif

Heh, sorry about that. It was late when I posted.

However, I still don't understand how scientists can create fusion and expect it to stop on its own. The type of fusion they're trying to create is for the purpose of propetual energy generation-- more energy is created than is used in creating it. If this is so, fusion should be able to grow on its own, and infinitely so. But even it does rely on a finite fuel source, whose to say that fusion only eats hydrogen pills? What if it decides that oxygen is just as tasty??

Are we prepared to put out an atomic fireball before it swallows us all? <insert smiley for good measure>

no, fusion can not be self-maintained cause it need extreme confinement (in the stars the confinement is obtained by the gravitation force)... but the mini black hole problem is not a joke!

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Raccoon said:However, I still don't understand how scientists can create fusion and expect it to stop on its own.

[/ QUOTE ] Thermal conduction through plasma is 10,000 times higher than that of the best solid or liquid thermal conductor we know of - if the plasma ever managed to get out of the magnetic bottle containing it and actually touch the reactor walls, it would immediately cool to below the minimum fusing temperature and quench the reaction ( within microseconds or less, depending on the size of the reactor ). It's one of the safest and cleanest forms of energy production you can get. Afterall, keep in mind that most fluorescent lights in your home operate at or above the surface temperature of the sun....and you're not too worried about those causing a meltdown even if they broke open during operation. The plasma in both your fluorescent lights and that of a fusion reactor is so rarified that it just isn't a danger in this manner.

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Raccoon said:The type of fusion they're trying to create is for the purpose of propetual energy generation...

[/ QUOTE ]No, actually not. Perpetual energy is not a viable idea from the perspective of classical physics and seeming violations of this law from a quantum mechanical perspective are likely the result of energy just being transferred from one unknown system into the one being observed at the time any seeming 'violation' of that law is witnessed.

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Raccoon said:...more energy is created than is used in creating it. If this is so, fusion should be able to grow on its own, and infinitely so.

[/ QUOTE ]No, not quite. More energy is released than is used in starting the fusion reaction - it's not created from out of nowhere. It's actually releasing the excess binding energy stored within the Deuterium and Tritium fuel's nuclei ( in the form of the Nuclear Strong force ) which is then released when the two hydrogen isotope nuclei fuse - it basically takes less total energy to hold toegether the newly fused hydrogen fuel nuclei ( which have now been fused into helium ) than it originally took to hold together the individual hydrogen isotopes on their own. It's by no means perpetual energy generation ( just like burning gasoline or coal is not perpetual energy generation ) - it's just a different method of extracting a portion of the energy contained within a substance and putting it to practical use. And just like burning coal or gasoline requires a spark ( energy ) to initiate the release of even more energy stored within the chemical bonds of those fuels, fusion requires it's own spark of sorts ( anything that can heat the reactants to over 1 - 10 million degrees kelvin ) in order to release some of the energy stored within its nuclear bonds so that we can harness it and put it to constructive use.

It is by no means a bomb and couldn't be turned into one despite the seeming similarity in the way energy is being released between it and an H-bomb. Sort of like worrying that your car will blow up your house everytime you start it just because miniature, contained, and channelled explosions are taking place within the combustion chambers of your car's engine....it just isn't going to happen because it's not designed to release energy in a mass, uncontrolled explosive manner. Just like a fusion reactor, it is designed to release relatively small, steady, and controlled amounts of energy ( compared to that of a nuclear bomb ). And the best thing is, after letting the reactor waste sit for about 20 years you can drink it and suffer little or no ill effects ! /ubbthreads/images/graemlins/smile.gif The low-level radioactive emissions from spent fusion fuel decay quite quickly ( which sits a lot better with me than the epochs that it takes to wait for spent Fission fuel to decay into something equally palatable ). Nice and clean energy.

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BeKarim said:no, fusion can not be self-maintained cause it need extreme confinement (in the stars the confinement is obtained by the gravitation force)....

[/ QUOTE ]Well actually it can, and already has been contained. It's done by using a magnetic bottle effect, which has been successfully containing super-hot plasmas for decades and decades now. Gravity doesn't actually contain the Sun's fusion reaction either - it just balances out the outward forces produced by such a massive, continual release of energy with an inward force that acheives equilibrum and allows the Sun to maintain a stable shape during the reaction. As a matter of fact, nothing 'contains' the Sun's energy. That's why it's warm and bright outside - we're currently receiving the energy that is being freely released by the Sun. The reason why we aren't usually harmed from it is because we are currently 93 Million miles away from 'Ground Zero' on that particular nuclear explosion ( and our sponsor, the 'inverse square' rule, is currently in full effect throughout the 93 million miles that are separating us ), which prevents us from receiving the full brunt of the Sun's energy release, and in so doing, being turned into a plasma ourselves.

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BeKarim said:... but the mini black hole problem is not a joke!

[/ QUOTE ]Too bad, it would have been much funnier if it were being told as a joke rather than a heinously inaccurate misconception ( I'm really not trying to be mean to you here BeKarim - these are just the facts my friend ). The densities acheived even within the very heart of our Sun ( which is hideously more dense than any fusion reaction we are producing here on Earth ) don't come even remotely close to the densities required to form a singularity ( ie - Black Hole ). No offense my friend, but your statement is patently untrue in this case. The only place that fusion reactions have a chance of forming singularities are within the realm of Japanese cartoons ( some of which make for quite interesting storylines might I add ). /ubbthreads/images/graemlins/sssh.gif


And on a lighter note.....this is kind of spooky. Me commenting on nuclear fusion sounds just like Darell pimping EV's and solar energy !!! /ubbthreads/images/graemlins/ooo.gif Ironic how closely related the two subjects actually are to each other. It must be the rays from Earth's yellow Sun that are giving both of us these special powers down here on this little planet. Hold on a second here, I'm going to dig up a cape from somewhere and see if I can fly now too !

I read a history of solar power today. In the 1950's Felix Trombe designed a solar furnace (using 9,000 mirrors) that reached 5,538 degrees celsius, which is the temperature of the sun.

WWWe've had fusion already. The current goal is a matter of making self sustaining fusion that is controlled. I'm looking forward to it.

Daniel

http://ned.ucam.org/%7Esdh31/misc/destroy.html

/ubbthreads/images/graemlins/wink.gif

Mark

what i said is that fusion cannot go out of control (i said self-maintained to trnslate from french "auto-entretenue"... dont know if the translation is correct) cause it need very high pression ("confinement" in french) and temperature that can't be obtained anymore if reaction bolts (s'emballe).

for the mini black holes it was in fact a joke although such holes could really be created in particle colliders:
www.cerncourier.com/main/article/44/9/22

so be carefull! /ubbthreads/images/graemlins/grin.gif

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BeKarim said:for the mini black holes it was in fact a joke although such holes could really be created in particle colliders:
www.cerncourier.com/main/article/44/9/22

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Now <font color="blue">that is</font> very interesting BeKarim my friend. I didn't even know we were approaching high enough collider energies to have the hopes of producing micro black holes. 14 TEV !!! Wow, that's a big jump since the last time I checked in on what the CERN team was up to. Very exciting stuff indeed - I can't wait till they make one ! /ubbthreads/images/graemlins/grin.gif

That is a great link to that article. I LOVE real science that reads like sci-fi /ubbthreads/images/graemlins/grin.gif

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The key point is that it allows the Planck scale to be reduced to accessible values, but it also allows the Schwarzschild radius to be significantly increased
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the resulting mini black holes have radii that are much smaller (of the order of 10-4fm in the case of those that can be expected from the LHC) than the size of extra dimensions, and that they can therefore be considered as totally immersed in a D-dimensional space, which has, to a good approximation, a time dimension and D-1 non-compact space dimensions. The black hole thus acts like a quasi-selective source of S waves
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the black hole evaporates into particles of the Standard Model.


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That last line is the important one /ubbthreads/images/graemlins/smile.gif They evaporate almost immediately into regular, (though still interesting) particles. I did read a really good novel the title and author of which I forget now where they got the physics of this wrong and there was an additional effect of radiating tao wave leaving perpendicular to the time cone carrying away enough energy that the black holes were allowed to survive long enough to eat enough mass to become self sustaining and there ended up being thousands of them orbiting through the earth and eating microscopic trails through everything until it all fell apart... Good novel, but not good science /ubbthreads/images/graemlins/smile.gif

Actually, all black holes "evaporate" eventually. The time scale on which this occurs is on the order of billions or even trillions of years for holes formed from collapsed stars but a mere 10-26 seconds for the micro black holes formed within partical accelerators.

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Minjin said:
http://ned.ucam.org/%7Esdh31/misc/destroy.html

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Minjin - those pages are frickin' hilarious ! /ubbthreads/images/graemlins/crackup.gif

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Mednanu said:
Thermal conduction through plasma is 10,000 times higher than that of the best solid or liquid thermal conductor we know of - if the plasma ever managed to get out of the magnetic bottle containing it and actually touch the reactor walls, it would immediately cool to below the minimum fusing temperature quench the reaction ( within microseconds or less, depending on the size of the reactor ). It's one of the safest and cleanest forms of energy production you can get.

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I believe the experiment being referred to by Raccoon is not of the magnetic bottle type--it is inertial confinement fusion, where lasers simply compress the fuel for a long enough time at a high enough temperature to fuse the hydrogen. But once the hydrogen is used up, the reaction stops. Oxygen won't be involved because the temperature for fusing oxygen is so much higher.

This form of energy production is relatively safe, but there are serious by-products. Since currently the technology is aimed at Deuterium-Tritium reactions (much easier than Deuterium-Deuterium reactions), there are bound to be neutrons flying all over the place, making the containment vessel highly radioactive. The helium and hydrogen left over would be relatively safe, but not the surrounding infrastructure.

Fusion does not involve a chain reaction similar to the fission schemes with Uranium and so on. In fact, the helium ash produced in the reactions actually impedes the fusion process. Thus, there is no worry of a China Syndrome for fusion reactors. But a Chernobyl is possible, that is, the release of radioactive by-products into the environment.

nisshin

It's true that the containment and support structures in a fusion reactor would eventualy become radioactive through neutron bombardment, However, it would take years of continuous operation in a sustained reaction, unlike the millisecond "cruncher" tests we're talking about here, and the radiation levels of such items would still be much lower on average than the spent fuel, or other contaminated structures from fission plants.

And "mee toos" on the chain reaction concerns raised above. It takes a great deal of energy to keep a fusion reaction going, and that's why it's been so hard to create a viable energy producing reaction. It's not like fission where there can be a chain reaction if too much fissile material gets together in one place. Any part in a fusion system breaks, it just stops. Unlike fission where most of the effort is expended in keeping the reaction under control, in fusion, most of the effort is in keeping it going.

The most basic analogy I can think of is that fission is like a smouldering pile of gunpowder, with stuff mixed in (control rods, coolant water) to keep it from going up all at once. You have to control it with the moderators, or just keep the fuel far enough apart. If you don't, watch out.

FUSION (Thx Rac...) is more like an internal combustion engine. If any part breaks, the engine stops, it dosen't go runaway on you. The confinmemt and pressure needed is like the cylinder compression, the input energy or imploding lasers are like the spark plugs. The feeding mechanisim is like the valves and fuel injectors. Any one of those things breaks, you grind to a stop. Being worried that fusion could "get loose" is a complete misunderstanding of how it works.

Thanks for the follow-up guys. These are mostly the same responses given by nuclear physisists here at Tech (NMT.EDU). The only thing I'm not sure about is the containment field becoming radioactive, but then I don't recall any mention of Deuterium or Tritium in the process either. The way it was described there would be alpha particle ash, but presumably contained and evacuated in the process.

PS: AJ_Dual - your last paragraph should say Fusion not Fission, right?