[aristophenes]

I don’t understand the appeal of this type of fusion (as opposed to the plasma reactor approach). We’ve known how to get positive energy out of fusion fuel since thermonuclear weapons in 1952. The really hard part would seem to be capturing that energy efficiently. This experiment is stuck at the ignition phase. When that’s positive energy they won’t be done, they’ll be able to start working on the practical problems of sustaining it. What am I missing.

[cstross]

What you're missing is that since the Comprehensive Test Ban Treaty came into effect it's illegal to test-detonate nuclear weapons. Which are narrowly defined in terms of fission devices, with or without a fusion booster.

Fission devices have been very well understood since the early 1950s, but fusion reactions are somewhat less so. The NIF provides an instrument for probing the plasma densities and temperatures that occur inside a nuclear fireball, so is directly relevant to H-bomb research.

This becomes trivially obvious when you realize that a laser implosion fusion reactor producing power would need to achieve in excess of ten ignitions per second to produce the sort of power output needed just to power its own lasers ... and that each hohlraum costs on the order of a third of a million dollars. (What kind of power plant costs $11Bn per hour to operate?) Answer: it's not a remotely practical design for generating electricity, so it must be something else, and promoting it as "clean energy from fusion power" is a cynical propaganda move to disguise a nuclear weapons research tool.

The final clue is that the NIF is operated by Lawrence Livermore National Laboratory, whose primary job is designing and ensuring the reliability of nuclear weapons.

[aristophenes]

This is why I often read the comments more than the articles here on hacker news.

[chriswarbo]

> We’ve known how to get positive energy out of fusion fuel since thermonuclear weapons in 1952

Indeed, the brute-force approach is to simply detonate a hydrogen bomb underground, tap off steam, then repeat. That was seriously investigated (I believe as part of Project Plowshare https://en.wikipedia.org/wiki/Project_Plowshare ), but the high cost of the bombs made it uncompetitive with other methods.

[motoboi]

I suppose you could look at it as a spaceship.

We have know for centuries that all you need to go high is a big fire pointing down, but soon realized that the hard part was maintaining the fire long enough to reach orbit or other planets.

And even when that would become possible, the problem of how to land in the destination, build shelters and grow food remains.

So, why we insist on this irrational pursuit?

First because we can.

Second because the the search needed to achieve that generates far more societal benefit than just the space goals.

And third because society can pursuit many goals at once. We have several people, just let them explore.

So, fusion is hard, but very probably not impossible. The pursuit of it will advance science and technology. If successful, can trigger societal changes we can only imagine today (serious carbon capture becomes possible. Smelting of very energy intensive alloys becomes cheaper and possible).

And if the ultimate goal of a miniaturized reactor becomes possible, our spaceships can fly basically anywhere.

[phreeza]

There was a project to collect energy from thermonuclear bombs by blowing them up in an underground chamber cooled by a shower of molten salt. It was abandoned because the cost of making the bombs was too high, not the energy capture.

https://en.m.wikipedia.org/wiki/Project_PACER

[user-the-name]

I don't know, what are you missing? You have fairly accurately listed the facts to the situation as it stands.

This is where we are at, that is what we are aiming for.

[the-dude]

That fusion is not fission?

[aristophenes]

Thermonuclear weapons use fission to ignite fusion, and is how modern nuclear weapons work. Developed in the early 1950’s.

[ganzuul]

My guess is they are actually researching femtotech.

ED: By now I assume I would be ignored if I was wrong.