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Nuclear physicist explains why fusion ignition is hailed as a major breakthrough

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Re: Nuclear physicist explains why fusion ignition is hailed as a major breakthrough

#251

Post by chasil »

chongli wrote: post #32
garyclarke27 wrote: post #9

Most interesting fact from the article. At the system level it took 300 million Joules to produce 3 Million a 1% return - so still a very long way to go! With this kind of approach I can’t see how fusion can ever be cheap, the capital costs are enormous. Better to focus on standardised production lines for small fission reactors.

That's not the only big challenge. The fuel pellets are 1mm diameter hollow spheres machined out of diamond to extreme precision and filled with a tiny amount of deuterium-tritium gas inside. The pellets need to be carefully cooled to cryogenic temperatures so that the gas condenses evenly around the inside of the pellet, in order to maintain the near-perfect geometry needed for ignition. Once the pellet is hit with…

The hohlraum cylinder itself is also made of gold.

Could it be made from a metal that is in greater supply?

Re: Nuclear physicist explains why fusion ignition is hailed as a major breakthrough

#253

Post by LatteLazy »

subradios wrote: post #23
LatteLazy wrote: post #8

The title doesn't match the contents. There is no actual justification of why this is a breakthrough. IMHO it's a milestone, not a breakthrough. This is because it is only a marginal improvement on previous results and it is very unlikely to significantly change the state of either the science or industrial products without further work.

This specific marker is a breakthrough. We did not know until three weeks ago if laser ignited fusion reactions could be created that released more energy than was transmitted into the fuel. Now we know it is possible, it has been done. The next question is, can we create enough industrial efficiency to create a working motor generator set. A hard problem to be sure, but proving that it is a problem that we have is i…

That is very small though, for a "breakthrough". That's my issue.

We already knew that laser ignited fusion worked (that it triggers fusion). And we still don't know it can produce more energy than it consumes overall (one of the big questions for this sort of fusion).

Really, we have gone from being 0.5% efficient to 1% efficient (I believe).

One way to describe that is doubling the output. And that is technically true. But it's quite misleading as it will have no actual impact in the real world.

Add to that that this was quite predictable. And that we will need at least 3 very big breakthroughs before this is viable (much more efficient lasers, a continuous method and either replacement of the fuel or a very easy supply of deuterium). I just don't see this as a big deal.

That's why I called it a milestone. It's progress. But it isn't huge, unexpected, change-in-the-real-world progress.

Re: Nuclear physicist explains why fusion ignition is hailed as a major breakthrough

#254

Post by hinkley »

myrmidon wrote: post #210
albertopv wrote: post #22

Real Engineering published a video about Helion Energy company. I don't have the tools to filter out commercial BS, still it seems to me to be most promising effort. The idea to get electricity directly from magnetic fields instead of boiling water is very intriguing.

What made me super skeptical about the project is that I could not find out any numbers regarding economic viability: 1) How much energy per pulse is a commercial device expected to achieve? 2) How many pulses per second are realistic? 3) How many tons of copper/steel/capacitors per MW of power capacity are expected? Because if you're gonna need a warehouse full of capacitors, several big turbogenerators worth of hig…

In the video they’re trying to transition to 1/s from 1/10s, and targeting 10/s in a future generation.

Always hard to tell from publicity shots, but it looked like their existing capacitor bank was around the size of a shipping container. That probably goes up with the frequency though. I’m not sure you can do single or dual banks when aiming to fire every hundred milliseconds. Plus I think you need somewhere to send the produced power for dumping into the power grid.

But they’re already trying to produce their own capacitors to deal with that level of cycles per hour. I could see these guys spinning out a couple of companies that supply other designs or even industries. Especially if the money runs out.

Re: Nuclear physicist explains why fusion ignition is hailed as a major breakthrough

#255

Post by throwawaymaths »

felipellrocha wrote: post #203
throwawaymaths wrote: post #158

Earlier quoted context omitted.

It's not even close to net positive. It's more energy out than the lasers put in. But the lasers take in WAAAAY more than they put in.

What are you talking about? They put in 2MJs of energy in, and got back 3.5MJs out?

If your "they" refers to the lasers, the lasers put in 2mj, correct. That is not what "they" (my they) put in to the lasers.

Re: Nuclear physicist explains why fusion ignition is hailed as a major breakthrough

#256

Post by hinkley »

hoseja wrote: post #81
albertopv wrote: post #72

Earlier quoted context omitted.

There is no energy harvesting system yet, next prototype will be include that. I like their "fast" (relatively speaking, of course) prototyping process.

Why not do a major announcement with the working prototype though, is what's ringing the alarm bells for me. Yeah sure they can promise the next prototype will do the magic thing but why not wait for that.

He says in the video that they miscalculated a bit of physics regarding angular momentum and the Trenta design I suspect suffers from erosion of the throat (and power loss) because of that. The new gen is 25% bigger to avoid contact between the plasma and the walls.

Re: Nuclear physicist explains why fusion ignition is hailed as a major breakthrough

#257

Post by throwawaymaths »

donquixote25 wrote: post #205
throwawaymaths wrote: post #162

Earlier quoted context omitted.

No it's not a breakthrough. It is only net positive because the NIF has an exquisitely stupid and convenient place where they are defining "energy in" which let's them cheat how good it looks. If you could take other types of fusion and draw a clever line around where you start tallying energy in, then they would have had "breakthroughs" long ago.

The definition of Q that is being used was established by the National Academy of Sciences not NIF. NIF previously tied to use the hot spot energy instead of target energy in 2013, which they were criticized for, and rightfully so. But this definition of Q is analogous to the definition of Q used by MCF.

Ok. So the NAS has an exquisitely stupid definition of Q which is not at all what most engineers would use as a reasonable definition of Q

Re: Nuclear physicist explains why fusion ignition is hailed as a major breakthrough

#258

Post by hinkley »

zmgsabst wrote: post #119
hoseja wrote: post #81

Earlier quoted context omitted.

Why not do a major announcement with the working prototype though, is what's ringing the alarm bells for me. Yeah sure they can promise the next prototype will do the magic thing but why not wait for that.

This one already does reliable aneutronic fusion using an unusual method. Why not announce that?

I think doing an episode of Real Engineering counts, personally:

https://youtube.com/watch?v=_bDXXWQxK38

Re: Nuclear physicist explains why fusion ignition is hailed as a major breakthrough

#259

Post by hinkley »

albertopv wrote: post #57
moffkalast wrote: post #53

Earlier quoted context omitted.

I've also been quite surprised watching that one, it's completely novel approach to fusion and it may be the best way to mass adoption. If they can make it work that is. 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. Turns out they'r…

I'm very skeptical about those great announcements, even more when there's an announcement of the announcement. 300MJ in, 3MJ out, I wouldn't call it a breakthrough, maybe a milestone, nothing more.

Someone said in another comment that they elected to use old lasers, and that state of the art are about 40x more efficient. That’s still a big gap, and I’m dubious about the tritium supply, and the amount of beryllium they’re using to breed the tritium. Also tritium is nuclear proliferation of fusion bombs.

Re: Nuclear physicist explains why fusion ignition is hailed as a major breakthrough

#260

Post by hinkley »

jackmott42 wrote: post #107

I can tell you that regular people took the announcements as a sign that nuclear fusion as a real useful thing is imminent, and couldn't be convinced otherwise! But then if your announcements are completely rational you don't get as much funding. A lot of us nerds on HN don't like it when people do propaganda, but I assume we also like to win, right?

When people have been doing the propaganda for longer than I have been alive, I become an old, salty fucker.
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