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ItsAConspiracy t1_j0cogb1 wrote

Reply to comment by saltyhasp in Nuclear fusion breakthrough: A physicist answers three vital questions by FarmhouseFan

The article does not say we're 2 to 3 orders of magnitude away. It does mention that we have much better lasers now.

NIF's lasers date back to the 1990s and are only 0.5% efficient. We have NIF-class lasers now that are over 20% efficient. That drops the input power to the lasers by a factor of 40.

So if NIF manages to increase the fusion output by a factor of ten, we can substitute modern lasers and have enough extra power to be net positive after running a turbine.

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saltyhasp t1_j0crlto wrote

Using the numbers the article gave the current closed loop gain is about 1/357. Third laser efficiency is about 0.67%. Go to 20% laser efficiency is 30X. This brings the closed loop gain to 1/10.5. Improving the energy generated by 10X. You get to a closed loop gain just short of 1 at 0.95. So you need more then 10x. This assumes a 30% output to electricity conversion.

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ItsAConspiracy t1_j0cv8bb wrote

The link I posted puts NIF laser efficiency at 0.5%. Either way, roughly one order of magnitude gets us over practical breakeven. Get to 20X and we've got a solid margin. Two orders of magnitude would be around 100X but we don't need to go near that far.

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