National Ignition Facility - Progress

[Otispunkmeyer]

So in Euro we have the ITER project. A fusion project that uses the toroid and magnetic confinement of plasma to sustain a fusion reaction. It is expensive though and across the pond, there is a second method being researched at Lawrence Livermore that is much cheaper and uses laser-confinement to produce enough heat and pressure to start fusion. (well actually, the lasers hit a container that produces intense X-rays and these do the imploding of the DT fuel pellet).

It nearly got shut down because nothing was happening and it cost more than originally proposed (although still cheaper than ITER). They have apparently managed to almost break even. The amount of energy absorbed by the fuel was just about returned when it underwent fusion at about 8000 J.

The headline is not as good as it sounds though because the 192 lasers actually delivered 1.7 MJ (the device that absorbs and emits X-rays only absorbs some of the laser light and in turn the pellet only absorbs some of the X-rays). To make that sound even worse, over 3 MJ of infrared radiation is also needed and if you go even further down the chain, as the lasers are capacitor pumped (old technology now we have diode pumped lasers) the actual energy input was over 400 MJ!

So it doesn't look that promising at < 1% of the energy returned. They reckon they can get to 15% with newer diode lasers as they are not as wasteful as capacitor pumped ones.

http://www.dailytech.com/Mankind+Creeps+Closer+to+...

[Russian Rocket]

it does however make a really cool looking warp reactor so you can boldly go.....

[anonymous-user]

Indeed, but you have to start somewhere!

---

>







;-)

[Simpo Two]

Otispunkmeyer said:

The amount of energy absorbed by the fuel was just about returned when it underwent fusion at about 8000 J.

Surely the trick once fusion starts is to feed more hydrogen in and the reaction will then give net yield?

[hairykrishna]

Simpo Two said:

Surely the trick once fusion starts is to feed more hydrogen in and the reaction will then give net yield?

It only fuses when it's all confined close together and the natural tendency when it all starts fusing and getting hot(ter) is to push apart. There's nothing keeping it together in this case apart from the initial photon pulse so just feeding in more hydrogen isotopes unfortunately doesn't work.


The only reason NIF got built and funded is that it's recreating the secondary phase of a hydrogen bomb on a smaller scale. It let the nuke designers experimentally validate their computer codes even with the comprehensive test ban treaty in place. It'll be great if it ever leads to feasible fusion power but, to me, the engineering difficulties are much larger and riskier than the ITER approach.

[Russian Rocket]

wiki siad said:

The high beta fusion reactor design under development at Lockheed Martin's Skunk Works is expected by the company to yield a functioning 100 megawatt prototype by 2017 and to be ready for regular operation by 2022

I find this interesting, it not like they are a tiny company with no previous

I think the torus @ ITER is more promising than the NIF. The NIF sounds promising until you read into the details of the laser system. the cooldown time between firings is so long they can only do about 700 firings a year

[Simpo Two]

hairykrishna said:

It only fuses when it's all confined close together and the natural tendency when it all starts fusing and getting hot(ter) is to push apart. There's nothing keeping it together in this case apart from the initial photon pulse so just feeding in more hydrogen isotopes unfortunately doesn't work.

Ah yes... and the sun is held together by gravity... so any fusion reactor would have to be rather big... suddenly I don't see this working as a viable energy source.

Dilithium crystals, that's what we need.