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Cold Fusion

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China Doll | 16:45 Tue 02nd Oct 2007 | Science
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Afternoon All,

Well you can thank the peg legged one for this....

What's cold fusion? Is there a hot fusion?

I did google it, (that's how I found the term hot fusion too) but on reading one of the articles I found I just got confused.

So thought I'd come here to get explained to me in ways I understand!

Cheers
China
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An atom of Uranium is large - well by atomic standard it is, 235 or more protons and neutrons and it only just holds together. Give it a shove with a few stray neturons and it'll split.

When it splits it releases energy this is fision - it's the way nuclear power stations work.

Hydrogen is the smallest element - 1 proton maybe a neutron or two. If you can get a couple of them close enough they'll stick together and make Helium and there will be energy left over. This is fusion and is how the sun shines.

If we could make a power station work on fusion rather than fission there would be big advantages - the raw fuel would be water, the safety aspects would be vastly better than todays power stations and the waste would be tiny and short lived.

But it's difficult - we've been at if for 50 years and it'll probably be about another 40 before you boil your kettle from one.

It's hard because you have to get those hydrogens close enough and the electric charges push them away like trying to put 2 magnets together so they have to be hot , very hot as hot as the sun.

About 20 years ago it was claimed that people had found a way to do it at room temperature (cold fusion)- I was working as a physicist on fusion experiments at the time and the science was pretty nonsense - we rather groaned as it was clearly going to be a media sideshow -it was.

The US military still fund a bit of research on it as a kind of lottery ticket but don't hold your breath.

Meanwhile ITER is being built in France
http://www.iter.org/ which will be followed by DEMO - the first fusion power station

It's been a long time coming but the rewards are enormous.
Question Author
Thank you :c)

(That'll learn ya to not go all round AB with your fancy science language!)

I remember now...You've told me about this before actually but not in as much detail. (When I was asking questions about the article in the Independent). You were once a little cog in all that I seem to recall!

Why are they giving it any funding if it's a load of rubbish? Surely that's what is classed as a waste of money?!
Reiterating Jake�s characterisation, it�s a chance in a trillion to make gobs of money yet so far the lottery is still proving to be the �wise� alternative to investing in �cold fusion�. With that in mind research is not necessarily a lost cause; even if it only proves you�re wrong the knowledge gained can prove beneficial.

. . . �You can�t win if you don�t play!


Now that your brain has had a rest here�s some more splanin�:

Warning! Some violence, nudity and strong language . . .
Fusing hydrogen atoms in helium atoms requires the bonding of four protons into two protons and two neutrons. Two of the protons are converted to neutrons with a release of their positive charge. It is the positive charge of protons (like charges repel) that keeps them apart and helps to keep hydrogen from spontaneously combining to form helium and larger atoms.

Before two protons are united the hydrogen atoms that are their source must be ripped apart exposing the protons. In the Sun extreme temperatures within its core tear electrons away from hydrogen atoms leaving the protons exposed so that they can be forced together by the extreme pressure that also exists in its core.

The heat required to expose hydrogen�s protons was initially generated by the friction of moving atoms. The entire mass of the Sun bears down on its centre pushing atoms together concentrating the heat already present causing the increased rate of collisions that generate more heat. Once gravity succeeded in pulling the Sun into the required mass and density to provide the necessary heat and pressure for fusion, a star was born.

�Cold fusion� is an attempt to force fusion without the extreme pressures and temperatures present within the Sun�s core.

how fusion creates energy
Jake-the peg, you say that 'the safety aspects would be vastly better than today's power stations'.
'Vastly better' implies that today's power stations are dreadfully unsafe. I didn't know that, and have never been aware of anything to suggest it.
Please explain.
I wsa specifically referring to existing nuclear power stations.

A Fission reactor typically has many months worth of fuel in it's core - if something goes wrong you get Chernobyl.

A fusion reactor typicaly would have no more than a few minutes worth of fuel and it's the devil's own job to keep it running.

This is why I say it's inherently safer.

As for conventional coal powered power stations America alone had 28 deaths of coal miners in 2004 and China had 6,000.

So I guess you have to ask safe for who?
Question Author
Hiya mibs

My explanation of protons and electrons (done on more or less a daily basis so if you're smart enough you can probably guess what area I work in).

'Protons are the beams that penetrate deeply. Electrons are the whizzy ones and are far more shallow in their penetration.'

True story. ^^^

I had no idea these little guys had so much more potential.

I reallys struggle with all this. (Physics was never a strong point). This are teeny, tiny, not even a pin prick things. So the amount of heat and energy and the size of the technology used (linear accelorators I'm thinking of specifically at the moment) to control them really, really hurts my head!

And the glass of wine I've just drank meant that I had to ready your explanation a good couple of times there Mibs. (I've given up on your link for this evening, will try again tomorrow!)
China, after re-reading my 'explanation' I would think that a glass or two of wine might be prerequisite to making any sense of it. I'm actually a little embarrassed to say I hadn't already had a few myself when I wrote it. I am without an excuse . . .

Hopefully the link will be an improvement.
I think mib was fleshing out a few of the bits that I'd skirted over.

The beginers guide version is that I said you just bring a couple of protons together - that was a fib.

You need a pair of neutrons too - they act as the glue that makes it stable.

In the sun the neutrons are made in that long complex cycle in mib's post.

We dont do that on earth, we use duterium which is a hydrogen with a single neutron ( as found in "heavy water") and tritium which has 2 neutons already attached.

It's a lot more efficient that way

I know what you mean about the size of the equipment it's not because of the size of the atoms but the energy that we need to put in.

We're bottling a little piece of the sun and that's not easy
Question Author
Heavy water?

I thought that was when I had to carry a 2 2litre bottles of water home because my housemates car had a strop!

I do like the idea of bottling a little bit of the sun though. I might incorporate that in to my explanations of the equipment. It makes them sound a bit more cheerful at any rate. :c)

Have you ever watched the Disneys version of Aladdin? There's a line in it, 'phenominal cosmic powers... iddy, biddly living space.' It's not as technical as the answers you and mibs gave but erm... well it's kind of helped me visualise it all!
When light nuclei fuse fuse to form heavier nuclei, stronger inter-nucleon bonds are formed (up to the element iron)
The force involved here is the Strong Force. It's a principle in chemical reactions that energy is released when the products of the reaction have stronger bonds than the reactants, as seen for example in an explosion.
Similarly, the nucleons in helium are more strongly bonded than the nucleons in deuterium. Thus when deuterium nuclei fuse to form helium nuclei there is a release of energy.
The activation energy for fusion reactions is very high. It seems highly unlikely that such reactions can be sustained at room temperatures.

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