Real-Life Weirdness

[Anaraxes]

Originally Posted by Varyon

(modern lasers are rather inefficient)

I don't think the National Ignition Facility has put any real effort into making their lasers efficient. ITER aspires to be a functional 500 MW reactor if and when it works. NIF is instead a scientific testbed. One of their main research areas is the design of the fuel pellets and changing the timing and shape of the laser pulse to improve yield. The lasers themselves have been around for over 20 years; I couldn't tell you how old the design is. One source I saw mentioned the lasers were 1% efficient (that is, 200 MJ input to get that 2 MJ pulse that produced the 3 MJ of power from the target pellet). That source claimed that the lasers could be made about 40% efficient, which is a pretty significant difference. Not enough even then to break even (5 MJ -> 3 MJ). That's fusion for you.

But NIF doesn't spend their money on that, because even terrible efficiency is good enough for their purpose. (It might take minutes to charge up those 200 MJ, but they're only igniting pellets one at a time anyway, resetting instruments, changing things for the next experiment.) A real reactor using their results is going to have to care a lot more about the laser efficiency.