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> What most surprised me about NIF's ignition announcement was that this was even news. I'd assumed for years that most if not all tokamaks and stellerators cou

by elihu 4y ago

> What most surprised me about NIF's ignition announcement was that this was even news. I'd assumed for years that most if not all tokamaks and stellerators could already achieve at least some brief fusion, just not to a useful degree. I think they've done fusion in tokomaks and stellerators before, it's just that the energy applied to the plasma is greater than the additional energy that's created by fusion. It's not that no fusion is happening at all in the most powerful magnetic confinement devices yet built, it's that there isn't very much of it happening. That's my layperson's understanding anyways.

moffkalast 4y ago
I'm not sure if it's true or not exactly, but I don't see how the NIF experiment would be any different from that if that were true, and in that case it wouldn't be news at all. It's not like they didn't use absurd amounts of laser power to get a tiny poof.
- IanCal 4y ago
  But there was more energy released than laser power going in. That's what the news was about
  - emptyfile 4y ago
- floxy 4y ago
  Going from a Qplasma of 0.9 to 1.5 for inertial confinement fusion seems like a step-change to me. For gains greater than one you have a positive feedback mechanism going for you -- the fusion you create makes more and bigger fusion. It is the difference between a tiny little bomb that works or doesn't work. It's this positive feedback that make scaling up potentially "easier". That's why it is a breakthrough, and concerns about lasers, etc. seem to be getting the cart before the horse. On the other hand, for magnetic confinement fusion, going from the same Q=0.9 to Q=1.5 is a much more "meh" event. I can see why some people are concerned about "where to draw the line" about total energy consumption, if it were MCF we were talking about. Maybe people have the expectation that ICF is further along the learning curve than it actually is? That's not to say that ICF is going to be viable for commercial fusion reactors in future. There are still many, many hurdles to cross. And maybe they will never be crossed for financial reasons.

by elihu 4y ago

moffkalast 4y ago

I'm not sure if it's true or not exactly, but I don't see how the NIF experiment would be any different from that if that were true, and in that case it wouldn't be news at all. It's not like they didn't use absurd amounts of laser power to get a tiny poof.

IanCal 4y ago
But there was more energy released than laser power going in. That's what the news was about
- emptyfile 4y ago
floxy 4y ago
Going from a Qplasma of 0.9 to 1.5 for inertial confinement fusion seems like a step-change to me. For gains greater than one you have a positive feedback mechanism going for you -- the fusion you create makes more and bigger fusion. It is the difference between a tiny little bomb that works or doesn't work. It's this positive feedback that make scaling up potentially "easier". That's why it is a breakthrough, and concerns about lasers, etc. seem to be getting the cart before the horse. On the other hand, for magnetic confinement fusion, going from the same Q=0.9 to Q=1.5 is a much more "meh" event. I can see why some people are concerned about "where to draw the line" about total energy consumption, if it were MCF we were talking about. Maybe people have the expectation that ICF is further along the learning curve than it actually is? That's not to say that ICF is going to be viable for commercial fusion reactors in future. There are still many, many hurdles to cross. And maybe they will never be crossed for financial reasons.