Scientists to use Tritium and make mini-Sun!!!

[Thunder]

http://news.yahoo.com/s/space/20090408/sc_space/friendlydeathstarlasertorecreatesunspower

They are gonna fire 100 lasers at a small amount of Tritium, heating it up to 150 million degrees..and make a mini-Sun!!!!!

Just like in Spiderman 2.

Is this possible? What will something at 150 million degrees do? wouldn't it just melt straight down to the Earth's core? ignite the Earth's atmosphere?

have such intense gravity that it would destroy the Earth?

oy vey!!

[Malkuth]

This sounds just like what they did in one episode of Eureka. Hope the scientists involved in this experiment don't eat the gmo chicken.

[KingMerv00]

have such intense gravity that it would destroy the Earth?

Why would nuclear fusion create gravity?

(Be aware my sarcasm detector isn't the best.)

[GreyICE]

http://news.yahoo.com/s/space/20090408/sc_space/friendlydeathstarlasertorecreatesunspower

They are gonna fire 100 lasers at a small amount of Tritium, heating it up to 150 million degrees..and make a mini-Sun!!!!!

Just like in Spiderman 2.

Is this possible? What will something at 150 million degrees do? wouldn't it just melt straight down to the Earth's core? ignite the Earth's atmosphere?

have such intense gravity that it would destroy the Earth?

oy vey!! I know it's in jest, but after the strange matter destroying the universe claim got as much legs as it did, I'm inclined to call for a moratorium on joking around science, on the basis that the insane can never tell.

(FYI containing a 150 million degree plasma is no problem, containing it with matter is no possible)

[shadron]

They've been talking about this sort of fusion power reactor for at least thirty years now (I can remember reading a SciAm article on such a theoretical design in undergrad in the 60s). In that design they have a laminar vortex of water, drop a deuterium/tritium pellet at a rate of something like 15 times a second, and zap it with lasers as it drops through the center. It implodes and fuses, and heats the water around it, the heat is drawn off by heat exchangers.

I presume that there are large problems with doing it or they would have long ago done it. Perhaps it has had to await sufficient computer power to control the lasers, or high strength materials to absorb the shocks.

[arthwollipot]

More that it still uses more power than it produces, I had thought.

[Cuddles]

More that it still uses more power than it produces, I had thought.

Pretty much. That's the whole point of this new experiment - to try to actually get more out than goes in. If that works, it should just be a matter of working out the details. Admittedly those details may take quite a while to work out, but once we've proved it can be done, it's a fair bet that eventually it will be done.

[drkitten]

OMG! Humans are going to use tritium to create fusion.

In other news, Truman wins re-election and Princess Elizabeth is crowned Queen.

[sol invictus]

Is this possible? What will something at 150 million degrees do? wouldn't it just melt straight down to the Earth's core? ignite the Earth's atmosphere?

have such intense gravity that it would destroy the Earth?

oy vey!!

The process in question is very similar one used in hydrogen bombs (not like the fission bombs dropped on Japan during WWII - like the current nuclear arsenal of the US, Russia, etc.). Hydrogen bombs have been tested at least several times since 1950s, so far with no atmosphere ignition - and they are much more powerful that this tiny explosion will be. As for gravity, it is precisely as strong after the explosion as it was just before, because gravity acts on energy in all its forms.

The advantage of the NIF is that the reaction is very small and can be controlled and observed from close range. Ultimately it might allow a form of controlled fusion power, but I suspect the motivation is actually more as a test of fusion to help design nuclear weapons.

[Vermonter]

I'm all for it. Who knows, maybe they will be able to devise a solution to contain it. If nothing else we'll find one more way to blow things up, and another attempt at energy that didn't pan out. If and when we ever do establish a fusion reaction, we should call it FR-40! (Fusion Reactor, attempt #40).

[INRM]

Cuddles,

I thought Robert Bussard developed a system that actually did produce a surplus of energy from a fusion reaction...

[Thabiguy]

I thought Robert Bussard developed a system that actually did produce a surplus of energy from a fusion reaction...

Just producing a surplus of energy from a fusion reaction is not enough; that already happens in thermonuclear explosions.

The key to fusion power is to develop a system that can sustainably produce more electric energy from fusion than it consumes. No such system has been developed yet. (On the other hand, such a system is already technologically feasible, so at this moment it's mostly just a matter of time and investment - and of course further research to make these systems increasingly practical.)

[soylent]

I presume that there are large problems with doing it or they would have long ago done it. Perhaps it has had to await sufficient computer power to control the lasers, or high strength materials to absorb the shocks.

1 kJ, not enough for a low gain.

Attempt to increase uniformity, twiddle with the pulse shaping and increase laser energy by a factor of 10 to try to defeat raleigh-taylor instability. Repeat until good enough.

This chart describes the situation very well(the triangles are inertial confinement fusion): http://www.plasmas.org/F-fusion-progress.jpg

[soylent]

I thought Robert Bussard developed a system that actually did produce a surplus of energy from a fusion reaction...

No. He produced a series of small models, derived some scaling laws and extrapolated 6 orders of magnitude out in terms of power output. If you actually try and build a full scale(break even or better) version you'll most likely find that things didn't work out so nicely.

If it still look somewhat promising you might build a bigger polywell, and if that makes progress but still not quite enough, you build an even bigger one. That's how you get to a project the size of ITER.

[arthwollipot]

OMG! Humans are going to use tritium to create fusion.

In other news, Truman wins re-election and Princess Elizabeth is crowned Queen.The sarcasm! It burns!

[Eos of the Eons]

May. In May we'll see. That's only one month away. What kind of cotainer will hold this thing, and will be a complete vacuum?

[soylent]

Most of NIFs shots will be dedicated to nuclear weapons design and maintenance. In addition to fusion research there will also be some applications for astrophysics.

May. In May we'll see. That's only one month away.

As far as commercial fusion power goes it's kind of irrelevant actually.

You probably won't be able to make the hohlraums cheap enough, so the lessons learned may have little applicability to the direct drive you might need. You'll have to repeat the process with fuel capsules that cost tens of cents rather than tens of thousands of dollars, with lasers capable of firing ~10 times per second rather than a few times per day, with a vessel somehow protected from the constant bombardment with 14 MeV neutrons(probably involving liquid FLiBe as both heat transfer medium, neutron shielding and for tritium production).

You're going to have to do this at a competitive cost or it is all pointless.

What kind of cotainer will hold this thing, and will be a complete vacuum?

It's a 10 metre in diametre aluminium sphere, 10 centimetres thick, with a deep vacuum.

If llnl.gov doesn't mind being hotlinked there will be a picture below:
https://www.llnl.gov/str/September03/gifs/Moses5.jpg

In the centre, on an arm protruding from the side of a wall there will sit a 1 cm long hollow gold-plated cylinder(a hohlraum) containing a precisely uniform 2 mm hollow pellet with frozen deuterium and tritium uniformly coating the inside. The 192 lasers will hit their target with a tolerance of 50 microns and 30 picosecond timing, heating up the inside of the cylinder until it begins to emit intense x-rays which will compress the capsule. This indirect drive system wastes a lot of energy, which doesn't make it to the 2 mm target capsule, but it will compress the capsule more uniformly than having the lasers directly hit the capsule.

[Cuddles]

Cuddles,

I thought Robert Bussard developed a system that actually did produce a surplus of energy from a fusion reaction...

The point is that there are many different methods of producing fusion. As already noted, uncontrolled nuclear explosions are very easy to produce excess energy. When it comes to controlled fusion for producing power, there have been two main approaches. Magnetic confinement passed the break-even point a while back, and the next major experiment - ITER (http://en.wikipedia.org/wiki/ITER) - is focused on doing so in a sustainable manner.

The experiment that this thread is about is NIF (http://en.wikipedia.org/wiki/National_Ignition_Facility), which is the next experiment to look at inertial confinement fusion. This method of producing fusion has never reached the break-even point, so the main focus on research is to achieve that, since there's no point trying to work out how to extract the power if you haven't actually got any to extract.

As for Bussard's work, that's quite an interesting variation that combines approaches from magnetic confinement and electrostatic confinement. It's hard to find out too much about recent results, since most of it is kept confidential by the US Navy who funded most of the work. However, it's unlikely the Polywell has yet achieved break-even, and I don't know of any published work that suggests it has. I believe Bussard himself predicted many times that the next iteration of the design would be the breakthrough but, as with most predictions about all approaches to fusion power, predictions about what will happen in the next couple of decades rarely come true.

[Dilb]

The experiment that this thread is about is NIF (http://en.wikipedia.org/wiki/National_Ignition_Facility), which is the next experiment to look at inertial confinement fusion. This method of producing fusion has never reached the break-even point, so the main focus on research is to achieve that, since there's no point trying to work out how to extract the power if you haven't actually got any to extract.

Eh, not really. Nobody expects this sort of inertial confinement is the way to economically produce power*. There are too many conversion inefficiencies, and turning it into a continuous process rather than a batch cycle presents a lot of difficulties. NIF is more interested in understanding how fusion reactions occur at high pressures and temperatures, like in nuclear weapons. I'm sure they'd like to get as much energy as possible out, but reaching the break even point is completely infeasible for them.

*Of course, after writing this, I find out that there are preliminary plans to replace all the lasers with high efficiency solid state ones, with the eventual goal of producing power, but those have a lot of issues to overcome.

As for Bussard's work, that's quite an interesting variation that combines approaches from magnetic confinement and electrostatic confinement. It's hard to find out too much about recent results, since most of it is kept confidential by the US Navy who funded most of the work. However, it's unlikely the Polywell has yet achieved break-even, and I don't know of any published work that suggests it has. I believe Bussard himself predicted many times that the next iteration of the design would be the breakthrough but, as with most predictions about all approaches to fusion power, predictions about what will happen in the next couple of decades rarely come true.

The weird thing about Bussard's polywell is that he claims he's already overcome all the engineering problems. Making a break-even model is supposed to be simple a matter of building a big enough reactor, because the efficiency will scale with the square of the size (energy produced scales as size to the 7, losses as size to the 5). If he had funding, Bussard says he could be producing power in a few years.

This is completely different from ITER designs, which have reached energy in=energy out, but still need substantial engineering developments to economically produce power. After the ITER research is complete (around 2040), it may be possible to build an actual power plant. It really depends on how much they can improve the plasma containment.

[AgeGap]

M39QJLnzcGM Part 1/6 Horizon - Can We Make a Star on Earth?

[rlr]

Laser fusion is almost exclusively a USA thing. It's considered much less promising a technology than the tokamak design that's favored in the rest of the world.

Also, there's no practical reason to do this research today, when fission breeder reactors work so much better and have so much readily available fuel.

For some reason a lot of people believe that fusion power would be inherently better than fission power in some way. Probably from taking SimCity as an authoritative source on its safety and cleanliness.

[arthwollipot]

Also, there's no practical reason to do this research today, when fission breeder reactors work so much better and have so much readily available fuel.Imagine what the world would be like if scientists took this as a guiding principle! :D

[rlr]

Yes, imagine what the world would be like if scientists didn't waste vast amounts of time and money on research projects with a low probability of success, when there are better things to spend that research time and money on, even within the same field.

Just imagine that. Because it will never actually happen.

[soylent]

Yes, imagine what the world would be like if scientists didn't waste vast amounts of time and money on research projects with a low probability of success, when there are better things to spend that research time and money on, even within the same field.

Would you have called the development of integrated circuits a project with a high probability of success without the benefit of hindsight? How about the internet? Hard drives? How about GPS or even just rockets capable of launching things into orbit?

[rjh01]

There is one big difference between fusion and all of those other things you mention. With fusion they have been experimenting with it on a large scale for decades with no major commercial benefit. But with the other things the things went into commercial production in less than a decade after they were invented. With rockets, it was a scale thing. Smaller rockets had been built and had been 'useful' for many years. No-one had even tried to build a rocket to go into space until WW2 ended.

[BenBurch]

Fusion has been ten years away from commercial development for 50 years now.

[Cuddles]

Of course, after writing this, I find out that there are preliminary plans to replace all the lasers with high efficiency solid state ones, with the eventual goal of producing power, but those have a lot of issues to overcome.

Yes, laser inertial confinement is very much meant as a way of producing power. It may also be used as a way of studying fusion for other purposes, but power is still a major goal.

The weird thing about Bussard's polywell is that he claims he's already overcome all the engineering problems. Making a break-even model is supposed to be simple a matter of building a big enough reactor, because the efficiency will scale with the square of the size (energy produced scales as size to the 7, losses as size to the 5). If he had funding, Bussard says he could be producing power in a few years.

Yeah, the big problem with Bussard is (or at least was, he's dead now) that although the polywell is actually not a bad idea at all, and may well be perfectly viable, he seems to go out of his way to make it seem like snake oil. I think this approach would probably be a lot further along by now if it had been promoted by someone with a much smaller ego and a little more common sense.

Laser fusion is almost exclusively a USA thing. It's considered much less promising a technology than the tokamak design that's favored in the rest of the world.

I'm sure Europe and Japan would be very interested to know that they are now part of the USA.

Also, there's no practical reason to do this research today, when fission breeder reactors work so much better and have so much readily available fuel.

Why bother with that? There's still plenty of wood lying around the place. Or could it be that having one thing that works is not a good reason to avoid researching new ideas?

For some reason a lot of people believe that fusion power would be inherently better than fission power in some way. Probably from taking SimCity as an authoritative source on its safety and cleanliness.

Alternatively, those people actually know what they are talking about, which appears to be something you lack in an awful lot of your posts.

[drkitten]

Would you have called the development of integrated circuits a project with a high probability of success without the benefit of hindsight? How about the internet? Hard drives? How about GPS or even just rockets capable of launching things into orbit?

Yes, yes, yes, yes, and yes.

[Thabiguy]

Yes, yes, yes, yes, and yes.

In that case, can you tell us five projects that are currently in early stages of development that have a high probability of success comparable to those just listed (i.e. as successful as integrated circuits, internet, hard drives or GPS)?

[shadron]

I just heard an interesting tidbit. H3 can be used in place of tritium for about the same energy yield in a fusion reactor. The difference is that H3 can be mined on the moon; there is reported to be some 100 million tons of it on the surface, left there by the solar wind. 25 tons, the weight load of the space shuttle for example, would be enough for a fusion reactor supplied with an equivalent amount of H2 to generate enough energy to run the USA for a year. Granted there are problems... Still, it's interesting to contemplate.

Source: The Cassiopia Project: Fission and Fusion
yTkojROg-t8

Support from http://media.www.eastfieldnews.com/media/storage/paper1070/news/2007/09/26/OnCampus/Mining.The.Moon-2994100.shtml

[Aepervius]

YOu have a typo. H3 (tri hydrogen) do not have any neutron, so forget fusion. You meant 3He , or helium3, a stable isotope of Helium with only 1 Neutron.

ETA: also to avoid confusion with stochiometry of molecule or cluster, you would not it 3He as all isotope are noted, except I have no idea how to do upscript in this forum

ETA ETA : it is SUP for superscript

[Tubbythin]

I just heard an interesting tidbit. H3 can be used in place of tritium for about the same energy yield in a fusion reactor. The difference is that H3 can be mined on the moon; there is reported to be some 100 million tons of it on the surface, left there by the solar wind. 25 tons, the weight load of the space shuttle for example, would be enough for a fusion reactor supplied with an equivalent amount of H2 to generate enough energy to run the USA for a year. Granted there are problems... Still, it's interesting to contemplate.

Source: The Cassiopia Project: Fission and Fusion
yTkojROg-t8

Support from http://media.www.eastfieldnews.com/media/storage/paper1070/news/2007/09/26/OnCampus/Mining.The.Moon-2994100.shtml

Assuming you mean 3He then the rather large problem is you're doubling the Coulomb barrier. Which means the fusing nuclei have to have much higher energies.

[rjh01]

No, shadron does not have a typo. The error is in the original article. This makes the original article either very confusing or wrong.

Errors
Ordinary Hydrogen powers the sun not H3 or He3.
Helium of any sort does not react chemically with anything.


We can mine H3 (hydrogen with two neutrons) from the sea. He3 may be harder to use as it has two protons instead of one and so has greater repulsive force for the same mass. (edit this last bit is what Tubbythin said above)

[neutrino_cannon]

Just producing a surplus of energy from a fusion reaction is not enough; that already happens in thermonuclear explosions.



Quite. I recall telling a physics teacher that there are in fact thermonuclear power converters that produce a net surplus of energy. Big, one use air dropped models that are useful for getting rid of inconvenient Russian cities. I don't think he thought it was nearly as funny as I thought it was.


And perhaps someone more knowledgeable can school me, but don't Bremsstrahlung losses make 3He fusion rather problematic?

[SirPhilip]

I believe Bussard himself predicted many times that the next iteration of the design would be the breakthrough but, as with most predictions about all approaches to fusion power, predictions about what will happen in the next couple of decades rarely come true. Doesn't antimatter research present a far more elegant solution, though? Assuming it could be manufactured far less expensively, large research funding devoted to containment could essentially solve the problem.

[Ocelot]

Doesn't antimatter research present a far more elegant solution, though? Assuming it could be manufactured far less expensively, large research funding devoted to containment could essentially solve the problem.

Not as I understand it. It take energy to create antimatter. The process is inefficient so you use more than you get from reacting it with matter. Antimatter can at best be and energy storage or transportation medium not an energy source. Unless you know of a place where we can mine antimatter or I've got entirely the wrong end of the stick.

[shadron]

Errors and such noted; thank you.

I recognize TubbyThin's objection. I don't know why it isn't mentioned in the original.

As for SirPhilip, I suppose that that depends on your process for creating anti-matter. One would think that the process of creating the stuff would use up all the energy of the annihilation, like the way that the energy derived from burning hydrogen equals the energy required to hydrolyze it from water in the first place. Unless one started off with some reaction particles and in the end they are all gone, having given up their mass into energy.

[RecoveringYuppy]

We can mine H3 (hydrogen with two neutrons) from the sea.
Don't think so. It's Deuterium, hydrogen with one neutron, that can be found in sea water in small but usable quantities (it's in the heavy water used in all kinds of research). Hydrogen with two neutrons is tritium and it's radioactive with a short half life. So there isn't any on Earth, it's all decayed.

[SirPhilip]

Not as I understand it. It take energy to create antimatter. The process is inefficient so you use more than you get from reacting it with matter. Antimatter can at best be and energy storage or transportation medium not an energy source. Unless you know of a place where we can mine antimatter or I've got entirely the wrong end of the stick. Let's assume hypothetically that antimatter follows a trend of drastically decreasing expense as ongoing research progresses to where a half kilogram could be manufactured for 20 million and contained. Assuming this could become a straightforward process, using a cluster of antimatter cells instead of a reactor would likely be a far safer prospect. Apparently there is general agreement that the input/output dilemma isn't a physically impossible engineering feat to reduce to a practical exchange. A, or the feat, nevertheless.

[sol invictus]

Let's assume hypothetically that antimatter follows a trend of drastically decreasing expense as ongoing research progresses to where a half kilogram could be manufactured for 20 million and contained. Assuming this could become a straightforward process, using a cluster of antimatter cells instead of a reactor would likely be a far safer prospect. Apparently there is general agreement that the input/output dilemma isn't a physically impossible engineering feat to reduce to a practical exchange. A, or the feat, nevertheless.

I think you might be missing the point. Anti-matter is useless for power generation, because to create it requires more energy than will be released when you annihilate it. One way to see that is to note that the cycle is closed: matter->antimatter->matter. At best it could be used as a portable power storage (i.e. fuel).

Fusion is different - you start with something and end up with something else, so you can extract energy from the difference between the two.

[RecoveringYuppy]

SirPhillip,

Not sure how you think a half kilogram of anti matter could ever be safe, but let's put that, rather fantastic, idea aside for a moment.

How could what you propose be safer than whatever you use in the first place to generate the energy you used to create the antimatter since it doesn't eliminate the need to generate the energy in the first place?

You're adding a step to the process, not replacing one step with another. Whatever dangers, however small, come with your "cells" they are in addition to whatever you're using to generate the energy in the first place.

ETA: That 1/2 kilogram of anti-matter (plus the half of regular matter it would react with) is about 22 megatons of explosive power.

[SirPhilip]

As for SirPhilip, I suppose that that depends on your process for creating anti-matter. Apparently the big bang itself was an event where an unstable volume of matter and antimatter separated with remnants scattered throughout the universe where antimatter hasn't had the opportunity to react.

If this was the case, they are particles with some manner of reversed polarity change without a change of state that behaves exactly the same as normal matter - as long as confined. A frightening implication of this is if a marble was transitioned, you wouldn't know except the instant it was taken out of confinement and it vaporized everything within a half mile radius in a flash of super bright light.

[SirPhilip]

Not sure how you think a half kilogram of anti matter could ever be safe, but let's put that, rather fantastic, idea aside for a moment. If a containment solution existed - the better question even could it - the key danger would be power loss. The key danger with fusion reactors is they are an elaborate system maintaining conditions close to a star's interior (!) on Earth. Unless I'm approaching this wrong and the ability to contain fusion reactions and antimatter have the same engineering context..

[sol invictus]

If this was the case, they are particles with some manner of reversed polarity change without a change of state that behaves exactly the same as normal matter - as long as confined.

That's true regardless of what happened after the big bang. Anti-matter is identical to ordinary matter, except with all charges (like electric charge) and spins reversed.

If a containment solution existed - the better question even could it - the key danger would be power loss. The key danger with fusion reactors is they are an elaborate system maintaining conditions close to a star's interior (!) on Earth. Unless I'm approaching this wrong and the ability to contain fusion reactions and antimatter have the same engineering context..

It still sounds like you're thinking of anti-matter as a source for power generation. Anti-matter is like dynamite - it's a state of matter which can be easily converted into lots of energy. But no one builds dynamite plants, because the energy required to produce dynamite is greater than the useful energy released when it explodes. Same for anti-matter.

[SirPhilip]

It still sounds like you're thinking of anti-matter as a source for power generation. Anti-matter is like dynamite - it's a state of matter which can be easily converted into lots of energy. But no one builds dynamite plants, because the energy required to produce dynamite is greater than the useful energy released when it explodes. Same for anti-matter. Isn't it possible at least potentially to channel how much antimatter would react at a given time, so the output would be a constant value? I'm assuming a half kilogram of antimatter would be in a solid or gaseous state. Reminds me of the engineering problem of using high explosive propellants to drive caseless projectiles. You could potentially throw the cartridge out of the equation with far better ballistics, but any conventional gun system would fail under the stress.

[Aepervius]

No, shadron does not have a typo. The error is in the original article. This makes the original article either very confusing or wrong.

Errors
Ordinary Hydrogen powers the sun not H3 or He3.
Helium of any sort does not react chemically with anything.


We can mine H3 (hydrogen with two neutrons) from the sea. He3 may be harder to use as it has two protons instead of one and so has greater repulsive force for the same mass. (edit this last bit is what Tubbythin said above)

In such case you cann it De (1 n eutron) Deuterium or T (2 neutron) Tritium. And not H3 or H2 or whatever. Maybe you would note it 2H or 3H

[drkitten]

Isn't it possible at least potentially to channel how much antimatter would react at a given time, so the output would be a constant value? I

Not relevant, I'm afraid.


I'm assuming a half kilogram of antimatter would be in a solid or gaseous state.

Assume it's an orange peel, for all it matters.

The problem is that you can't get that half-kilogram of antimatter, regardless of state, for less energy than you would get out of it.

A half kg is too much; let's just talk about grams. A gram of antimatter will liberate about 9 x 10^13 joules of energy.

But this also means it will take 9x10^13 joules of energy to make a gram of antimatter. This is about the energy contained in about 10kg of uranium fissioned all the way down to lead. Actually, it will take more, because of parasitic and conversion costs.

So why not just use the uranium directly?

[Soapy Sam]

I propose the use of antimatter batteries to store energy from windfarms.
These could be used to charge Galactic Patrol accumulators, should the need arise- and a few billion years be available.

[drkitten]

I propose the use of antimatter batteries to store energy from windfarms.
These could be used to charge Galactic Patrol accumulators, should the need arise- and a few billion years be available.

Yeah, that sounds brilliant, aside from the fact that we actually know how to build Duracells, and they don't unexpectedly explode and level cities.

[Soapy Sam]

You say that like it's a bad thing...:D

[Myriad]

It's worth noting (considering the thread title) that the goal of fusion reactor engineering is not to replicate conditions in the sun. That would require much higher pressures and much lower temperatures than any fusion reactor design (but still high enough temperatures that no conventional containment vessel would survive). Containing sun-like pressures at sun-like temperatures would be extremely difficult, but more important, it would also be useless. The sun overall produces less than a third of a Watt of power per cubic meter.

Respectfully,
Myriad

[RecoveringYuppy]

If a containment solution existed - the better question even could it - the key danger would be power loss.

Uh, yeah. In the case of your half kg, 22 megatons in a split second power loss.


The key danger with fusion reactors is they are an elaborate system maintaining conditions close to a star's interior (!) on Earth.

No, that's a key safety point. The conditions to maintain fusion are so foreign to Earth that any failure of the apparatus leads to the reaction stopping almost immediately.


Unless I'm approaching this wrong and the ability to contain fusion reactions and antimatter have the same engineering context.

"antimatter" is such a broad range of (potential) stuff that this question doesn't really makes much sense. Not if we're talking about the day when we have enough antimatter on hand to consider it a viable energy storage system.

In todays context, anti-matter and fusion are both produced in high energy particle accelarators. There is some overlap in engineering in that limited context.

[soylent]

This is about the energy contained in about 10kg of uranium fissioned all the way down to lead.

Uranium doesn't 'fission down to lead', it decays down to lead if you wait long enough.

If you fission uranium you get fission fragments distributed in two broad peaks, one around A ~ 95(e.g. strontium-90) and one around A ~ 137(e.g. cesium-137). Fission by fast neutrons gives a bit broader distributions and heavier actinides like curium shift the distribution a bit to higher atomic mass number.

Stable light elements tend to have a lower neutron to proton ratio than heavier elements like uranium. That's why you get a bunch of free neutrons when you split uranium and why these fission fragments mostly decay by beta emission(converting neutrons to protons and electrons).

[soylent]

It's worth noting (considering the thread title) that the goal of fusion reactor engineering is not to replicate conditions in the sun.

Nor is to replicate the fuel cycle. The rate limiting step is proton-proton fusion, which unlike any fuel cycle contemplated in fusion reactors here on Earth relies on the extremely short-ranged weak force to convert a proton into a neutron and a positron.

If you divide the total power-output of the sun by the total mass of the sun I believe you'll be pleasantly surprised.195 microwatt/kg

[Checkmite]

also, there's no practical reason to do this research today, when fission breeder reactors work so much better and have so much readily available fuel.

For some reason a lot of people believe that fusion power would be inherently better than fission power in some way. Probably from taking simcity as an authoritative source on its safety and cleanliness.

Hmm, good point.

[jasonpatterson]

Let's assume hypothetically that antimatter follows a trend of drastically decreasing expense as ongoing research progresses to where a half kilogram could be manufactured for 20 million and contained. Assuming this could become a straightforward process, using a cluster of antimatter cells instead of a reactor would likely be a far safer prospect. Apparently there is general agreement that the input/output dilemma isn't a physically impossible engineering feat to reduce to a practical exchange. A, or the feat, nevertheless.

Perhaps a comparable example would help, hydrogen power. Since free hydrogen is virtually nonexistant on Earth (antimatter is far far far more scarce than free hydrogen, but still) we have to make it from existing materials. In the case of hydrogen, that usually means electrolysis of water, which consumes energy. When the hydrogen is recombined with oxygen, it releases energy, but it releases the exact same amount that was consumed when it was freed from the water. When you figure in the unavoidable fact that the process cannot be 100% efficient, hydrogen becomes nothing more than a storage form for energy.

The exact same thing is true for antimatter, except that it's much harder to make, the technology to consume it is nonexistent, and storage for any sort of large quantity doesn't exist. We'd do better to use whatever energy we were going to use to make antimatter and simply make hydrogen instead, take it to wherever you plan on using your antimatter and burn it in an efficient turbine generator... The one exception might be space travel, but it likely would be far easier to get fusion working effectively for this purpose and collect the solar wind as fuel.

In either case, if we had an alternative source for the fuel in question, and the energy cost of extracting it was lower than the gain from using it, it would make a viable fuel. (Hydrocarbons, in the case of hydrogen, nothing, in the case of antimatter.)

[Ocelot]

Actually I've just realised. The laws of thermodynamics tell us that if anihilating x amount of antimatter releases y amount of energy then it will take at least y amount of energy to produce x amount of antimatter.

What we're forgetting is that when you anhilate x amount of anitmatter you also anhilate x amount of matter. And matter comes free - you can pick it up at any corner store ;-)

Thus you generate an amount of energy equal to 2y.

So producing anti matter and then anihilating it in a matter antimatter reaction could theoretically be of net benefit.

Now I know that our methods of producing anti matter are nowhere near that efficient. Not by many many orders of magnitude. However what's being suggested is now merely hugely impractical rather than against the known laws of physics.

The assumption I'm making of course is that there is an experimental method of making antimatter that doesn't produce and equal amount of matter. I can't find one though I don't believe any physical law that prevents it.

[Aepervius]

Uh. No. If there is y amount of energy in x gram of anti matter, it will cost 2*y to build the x amount of anti matter. Why ? Because of symmetry consideration. At the same time you build your anti matter you build the corresponding matter. You don't build your anti matter out of nothing.

So it is really a case of zero->zero.

[Ocelot]

Uh. No. If there is y amount of energy in x gram of anti matter, it will cost 2*y to build the x amount of anti matter. Why ? Because of symmetry consideration. At the same time you build your anti matter you build the corresponding matter. You don't build your anti matter out of nothing.

So it is really a case of zero->zero.

Like I said I couldn't find such a method and I was making that assumption - that you could produce antimatter without making and equal mass of matter. Which particluar symetry were you considering? I suspect that you might not be able to make anitmatter without making matter but equal mass?

[Aepervius]

Because all method we know to produce anti matter, are going to produce particle and anti particle at the same time. Which is why it is puzzling to have a universe composed of matter only, since our prediction for the reaction shortly after the bigbang only forsee a symetrical prediction of matter and anti matter. This is if i recall correctly named the baryon asymmetry paradox or something. I have not followed that part of science for some year so maybe there was a solution but i doubt it.

[drkitten]

Actually I've just realised. The laws of thermodynamics tell us that if anihilating x amount of antimatter releases y amount of energy then it will take at least y amount of energy to produce x amount of antimatter.

What we're forgetting is that when you anhilate x amount of anitmatter you also anhilate x amount of matter. And matter comes free - you can pick it up at any corner store ;-)

Thus you generate an amount of energy equal to 2y.

So producing anti matter and then anihilating it in a matter antimatter reaction could theoretically be of net benefit.


No. In creating x amount of antimatter, you automatically create x amount of matter as well. (Conservation of whatnot and all that). So you need to use 2y energy to make x amount of antimatter, and you get the matter more or less for free.

Then you burn the antimatter with the matter you made, and you get 2y back.

Less parasitic losses.


The assumption I'm making of course is that there is an experimental method of making antimatter that doesn't produce and equal amount of matter. I can't find one though I don't believe any physical law that prevents it.

Conservation of various physical quantities. For example, conservation of baryon number means you can't produce an antiproton without a proton.

[Singularitarian]

http://news.yahoo.com/s/space/20090408/sc_space/friendlydeathstarlasertorecreatesunspower

They are gonna fire 100 lasers at a small amount of Tritium, heating it up to 150 million degrees..and make a mini-Sun!!!!!

Just like in Spiderman 2.

Is this possible? What will something at 150 million degrees do? wouldn't it just melt straight down to the Earth's core? ignite the Earth's atmosphere?

have such intense gravity that it would destroy the Earth?

oy vey!!


I doubt it would work.

[Tubbythin]

Conservation of various physical quantities. For example, conservation of baryon number means you can't produce an antiproton without a proton.
Not strictly true since quarks can get shared around. For example I can't think of anything (though I could be wrong) forbidding the production of an antiproton, whatever you call an anti-baryon containing dbar dbar dbar, and two neutrons. But I'm just being a pedant.

[SirPhilip]

Because all method we know to produce anti matter, are going to produce particle and anti particle at the same time. Which is why it is puzzling to have a universe composed of matter only, since our prediction for the reaction shortly after the bigbang only forsee a symetrical prediction of matter and anti matter. This is if i recall correctly named the baryon asymmetry paradox or something. I have not followed that part of science for some year so maybe there was a solution but i doubt it. Likely the bang 'settled down' after the vast majority of reactions occured during the early universe. As matter and antimatter are for all practical purposes identical, why the universe is predominantly normal matter loses context.

[sol invictus]

Likely the bang 'settled down' after the vast majority of reactions occured during the early universe. As matter and antimatter are for all practical purposes identical, why the universe is predominantly normal matter loses context.

They're not identical - neither C (charge conjugation, which turns matter into anti-matter) nor CP (charge conjugation times parity, which turns left-handed matter into right-handed antimatter, etc.) are symmetries of nature. Only CPT, where T is time reversal, is a symmetry.

So a necessary (but not sufficient) part of the explanation for why there is more matter than anti-matter is that matter and anti-matter are not fully symmetrical.

[SirPhilip]

They're not identical - neither C (charge conjugation, which turns matter into anti-matter) nor CP (charge conjugation times parity, which turns left-handed matter into right-handed antimatter, etc.) are symmetries of nature. Only CPT, where T is time reversal, is a symmetry. So a necessary (but not sufficient) part of the explanation for why there is more matter than anti-matter is that matter and anti-matter are not fully symmetrical. Consider the uncanny but possible situation of an apple (taken from another region of the universe) carelessly tossed onto New York from a plane, leveling it. Assuming even a 30% variation of ratio at the start (borrowing from M-Theory rippling, colliding 11 dimensional branes), only rudimentary fragments would survive of each in separate regions of space that didn't react. If the apple analogy isn't satisfying though, consider falling in love with humans elsewhere composed of antimatter. Sad, but hilarious if that love was consummated.

[Monketey Ghost]

Fascinating thread!

[SirPhilip]

No, that's a key safety point. The conditions to maintain fusion are so foreign to Earth that any failure of the apparatus leads to the reaction stopping almost immediately. My reasoning is that assuming antimatter could become viable, a hypothetical solid state containment solution would be technically simpler. Unlike fusion, commercial antimatter would simply be an 'inert' gas or solid sphere suspended in a very strong magnetic field, without confining a constant temperature of millions of degrees that would have very strict operating rules. While fusion reactions have clear advantages, the stability of large scale reactors themselves remains in question.

[Dorian Gray]

May. In May we'll see. That's only one month away. What kind of cotainer will hold this thing, and will be a complete vacuum?I believe the container will be a bagless, and the vacuum a Dyson.

[Eos of the Eons]

I believe the container will be a bagless, and the vacuum a Dyson.

No doubt! :bgrin:


I haven't heard of anyone making a mini-sun, and this was all so last spring already.

[SirPhilip]

No doubt! :bgrin: I haven't heard of anyone making a mini-sun, and this was all so last spring already. They can't decide what they want to do first at the LHC though, a micro black hole or micro sun.

Scientist One: "Let's tell them we need additional modules to have the micro sun orbit the micro black hole afterward, another few billion in funding!"
Scientist Two: "And a salary increase per year!"

(Laughing with nerdy abandon echoes throughout the colorful cavernous assemblies..)