Fusion Power

[Mag]

My question is, for a Fusion Power Plant, how would that work?

I want to know essentially, dont you have to put in a great deal of energy to get it started in the first place?

And, what goes on that makes it produce even more (lots more)

 

thanks

[Klaynos]

Yep you do have to put alot in.

 

Nuclear fusion is when two atom's nuclei join together to form a single nuclei.

 

For elements less massive the Iron 56 when they join together they reduce the binding energy required to hold the nuclei together. This results in photons being given out with the extra energy.

[thedarkshade]

You really need to put a LOT in, like Kaly said. In sun, only the nucleus of it is hot enough to fuse. It's got to be really hot for fusion to take place.

 

i.e. For a fusion to take place in a fraction of a second (like hydrogen bombs need it) 100 million C is not enough. CTRs have temperatures of 100 million C.

 

Since 1950s, a goal for scientists has been fusion for power. But that is not easy since the temperatures required are as hot as (or hotter) than the center of the sun!

[swansont]

For elements less massive the Iron 56 when they join together they reduce the binding energy required to hold the nuclei together. This results in photons being given out with the extra energy.

 

Binding energy doesn't hold the nucleus together, the strong nuclear force does that. (sorry, you punched a button with that one) But more than that, the binding energy goes up in an exothermic reaction. BE is energy that's been released from the system, not energy contained in it, which makes it the amount of energy you'd have to add in order to dismantle the nucleus. Larger binding energy = more tightly bound = less mass (assuming the same constituent particles)

[Mag]

so what actually makes it so that it can supply power to things (assuming there was a fusion power plant)

 

[Mr Skeptic]

The energy released by the reaction. What form it takes hardly matters, eg you could extract energy directly from the ions (using the ions as the moving part of a generator), from the radiation released (like solar cells), or simply use the heat to drive a turbine, or a combination of the above.

[Mag]

ah gotcha.

So, therefore, if you were able to power one, wouldnt it be able to power itself?

[swansont]

ah gotcha.

So, therefore, if you were able to power one, wouldnt it be able to power itself?

 

That's the goal. Thus far the sustained energy yield is lower than the energy requirements.

[Mr Skeptic]

ah gotcha.

So, therefore, if you were able to power one, wouldnt it be able to power itself?

 

You got the right idea. However, so far it has taken more energy to heat up the plasma and contain it than it has generated, though I think they recently got one to reach breakeven for a short time. A proper fusion reactor would be able to power itself and supply extra power once it is started.

[Roger]

I believe the Japanese T-60 Tokamak generated net power in 1998, wiki article . Though I have more hope for alternative programs, I no longer think the toridial design (Tokamak) will work.

 

Inertial Electrostatic Confinement fusion has been around for a while. Work by Dr. Kulcinski @ U Wis in IEC fusion and especially the late Dr Bussards iteration of IEC, the Polywell, currently funded by the DOD, is very neat. Polywell wiki.

 

Polywell fusion relies on accelerating 2 particles fast enough, so that when they collide, they fuse. Heres a brief

showing electrons forming a potential well inside the magnetic grid ( McGrid). Ions are introduced inside the MCGrid, they see the potential well and are attracted to it, at high speed.

 

Dr Nebel. formerly of Livermore, is running the current Polywell program in Santa Fe, Recently his WB-7 device saw 1st plasma. A device the same size, but more powerful, would be capable of test runs generating 50Kev to 65Kev acceleration, where the PB-11 fusion can occur.

 

Boron 11 fusion would create lots of alpha particles, which would be directly converted to electricity via electrostatic grids.

 

Theory says a 500MW PB-11 net power reactor core would be 3 meters across.

[swansont]

I believe the Japanese T-60 Tokamak generated net power in 1998, wiki article .

 

No, it would theoretically have achieved Q>1 if it had been loaded with the proper D-T mix. http://en.wikipedia.org/wiki/JT-60 and AFAIK that still doesn't address how long the system would run under those conditions, so "sustained" is still a separate issue. (I included that word for a reason)

[pioneer]

I don't see why they don't just use the basic principals of H-bombs since these are a sure thing that we know will work. We take a near vacuum of LiD and shoot in energy from a conventional fission reactor. We just feed the vacuum chamber with LiD dust and maybe pulse the energy trigger.

 

Once fusion occurs the exothermic nature of this reaction releases energy. This is removed often with the circulation of liquid metals within heat exchangers. The liquids metals then undergo a heat exchange with water to make steam. The steam then drives turbines for electricity.

[swansont]

H-bombs have the tendency to melt things and blow them apart. Fusion for power is a much lower power application.