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Fusion

Ogo

Member
I was thinking of doing an 11th grade Chemistry science project on Atomic Fusion.
Mainly because we hear about it alot but very few people actually understand what it is. I am pretty clueless myself actually...

I would appreciate it greatly if someone could explain it simply or link me to somewhere that would contain information on the subject.

Thanks!
 
There are basically two types of nuclear processes, fission and fusion. Fission involves splitting the nucleus of the atom - pulling apart the protons and neutrons. Fusion, on the other hand, combines two nucleus's to form a single one. This actually creates a different element than what you began with. For example, the sun uses fusion - it primarily combines hydrogen to form helium. A hydrogen atom has one proton, a helium atom has two. Two hydrogens combine to form one helium. The neutrons don't matter as much, since it's the number of protons that determine what the element is - the same element can have different numbers of neutrons (they're called isotopes of one another). Fusion has a few advantages over fission in that it produces more energy, and is typically cleaner. The downside is that it requires a large input of energy to get it started.

Here's a website from doe.gov with more info.
 
With a fusion reaction, a constant input of energy is necessary to keep the reaction going. This energy is necessary to overcome the repulsive forces between atoms (normally there's a huge distance between individual atoms), so that they will fuse together (hence 'fusion').

The trick with creating a fusion reaction which outputs more energy than goes in lies in the used substances (usually two isotopes of hydrogen), the used type of reactor and various other factors. The best reactor so far outputs half the energy that goes in. A new fusion reactor which is currently under construction will output twice the input energy.
 
Two hydrogen atoms get mashed together to form a helium, which has something like 60% of the mass of the two hydrogen atoms. Because E=mc^2, the remaining 40% gets changed into energy. Fusion actually produces less energy per reaction then fission, but many more reactions can occur within the same amount of area, so it produces more overall.

At least, that's what I heard.
 
Not surprising Shalmanese, after all it's now possible to get a degree in Nuclear Chemistry...

It should be a fun project, I managed to get a tour of GD's fusion reactor here in San Diego. Fascinating to see how much equipment is needed just to heat the plasma to reaction levels. The reactor here is a purely experimental design that uses mostly deuterium, so they didn't have any of the heat removal equipment. I would like to see how they plan to trap the free neutrons and convert the kinetic energy into heat, and then move the heat out of the reactor itself.
 
I got to tour PPPL in NJ, where they had 2 reactors, their old tokamak (sp) is being dissassembled. They run all their tests on a tak of hydrogen the size that you would see in an ambulance (O2 tank). They also couldn't draw that much power from the grid all at once, so they had a ~300 ton flywheel that was underground (so it didn't fly off into nevermore).

Armani
 
I don't know much about this stuff but came across this site. I would want somebody who actually knew something about the stuff listed on that page, though to me some of it looks like it should work fine.
Check out the Farnsworth/Hirsch Fusor listed on the site, it is towards the bottom of the page.

If somebody doesn't mind taking a quick look at the site, and actually knows about some of this stuff, would you please post your opinion on it, yes I know much if not all could get me killed if I tried it, but I want a serious opinion, not just somebody saying to not try it since I know very little about it.
 
Sounds like an accedent waiting to happen. It is NOT something for you to even try, I am not even sure it will work, sounds quite fishy to me.

Armani
 
Elledan said this:

A new fusion reactor which is currently under construction will output twice the input energy.

Well, if thats true that solves all of the planets energy problems, right Elledan? Where did you get information on this? I'm kinda curious to know more.
 
Actually, there are two plants that are nearing positive energy with fusion reactors - one is British, and one is American. There may be others, but those are the only two I've seen.
 
Are you a professional in this field Kerle? Can you give us any info on when this can be mass deployed? Any possible ramifications of this?
 
No, I'm not a professional in the field; I work for an ISP.

But I do follow some of this stuff as a hobby; let me find some links for you.
 
astroview, I think you must have misunderstood something. What Elledan said was that you need more energy to keep the fusion reaction going than the energy that the reaction produces. He did not say that the reaction made energy out of nothing. Obviously you still need hydrogen for the fusion.

Imagine it like this: it is the same as if you needed extra electricity from an external source to keep the engine of a car running and the engine still would not be able to move the car.

Right now fusion does not provide energy, it takes away energy. Elledan was saying that there is a new method where if you input x amount of energy you will gain 2x. You will still need hydrogen, but the reaction will actually produce energy instead of using it.

<EDIT>
Ogo, there's a fusion research facility at my university, you may want to have a look at their page. Unfortunately this is a Japanese university so the main page is in Japanese, but they do have an English version with some limited info. Thought you might find it interesting. Here's a link:
Osaka University Laser Fusion Research
</EDIT>
 
I think I have misunderstood, I'm more of a sci-fi buff and a student of history and politics at my university rather than any sort of scientist. I know you can't break the laws of thermodynamics and create energy out of nowhere, but Palek, what Elledan referred to, does that mean fusion will create more energy than used to start the fussion process and be a source of power?

Or am I still mistaken?

 


<< Palek, what Elledan referred to, does that mean fusion will create more energy than used to start the fussion process and be a source of power?

Or am I still mistaken?
>>



No, you are right. That is what researchers are aiming for since it is a lot cleaner than fission, like someone else said before. We know it can be done since it works for the Sun 🙂. Now all they need to do is reproduce the process in a controlled environment.

<EDIT>How embarrassing... I just realized that I am the one who misunderstood YOU. 🙁 I thought your remark (something like "that should solve energy problems for all the world") was a sarcastic one... That's why I thought that YOU misunderstood something... Shoot me...

But on a more serious note, we must also consider that we will need a lot of hydrogen when fusion becomes a viable energy source. I actually have no idea whether or not hydrogen is common in its natural gaseous form and how much hydrogen gas is available. I suspect that water would become our primary hydrogen source, and while we do have a LOT of that, much thought still needs to go into what will be done with the resulting helium. The balloon industry would be very happy (and so would the people who enjoy inhaling helium for some vocal fun), but there would still be a large amount of helium left around. Also, splitting aqua molecules into oxygen and hydrogen requires a lot of energy too, so once you add that into the equation, I really do not know how efficient fusion will be.
</EDIT>
 
Actually, hydrogen production is not a problem; we don't really have the facilities set up at the moment in the scale that would be needed, but harvesting oxygen and hydrogen from the ocean is quite economically viable once we actually have functional fusion plants.

And of course, this would be moot if hydrogen fuel cell cars ever take off...
 
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