Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

New records on Wendelstein 7-X

iter.org

Post reply on HN
Print view View original

11–20 of 112 posts

Re: New records on Wendelstein 7-X

#11

Post by xorxornop »

ortusdux wrote: post #8
StevenWaterman wrote: post #7

Earlier quoted context omitted.

Your question reminds me of the image showing how SpaceX raptor motors evolved https://imgur.com/a/4w3q3lS

I'm not keen on the idea of applying a 'keep subtracting things until it blows up' mentality to fusion reactors.

I wouldn't be concerned about this, personally, for the precise reason that it is a fusion device - not fission!

Fusion is incredibly difficult just to start, let alone keep burning - unlike fission, which is only too happy to enter runaway conditions if not very carefully regulated. Fusion is like a little ember in your fireplace you have to carefully blow on to keep alight; fission is like keeping a fireplace lit by pouring gasoline into it.

Re: New records on Wendelstein 7-X

#12

Post by bradleyy »

In any future fusion power plant, a plasma with a high triple product must be maintained for long periods.

I love vague terms like "long periods". Long compared to the Planck length? Geological time? Is the advertised 43 seconds almost there or "off by 17 orders of magnitude?"

Re: New records on Wendelstein 7-X

#13

Post by Lev1a »

brohee wrote: post #5

Does it kill the idea of a tokamak as an energy production device? As in a stellarator proving the much more promising design...

Not an expert on the topic by any means, but IIRC:

- Those designs have been in parallel R&D for decades

- Tokamaks are conceptually simpler, thus might be easier/faster/cheaper to make into viable installations

- Stellarators are WAAAAAY more complex to design and build but AFAIU they would have the huge benefit of being able to sustain the plasma for way longer for the same "startup cost" of a cycle since the particles of the plasma are routed somewhat like they're on a mobius strip instead of a simple torus (which should make it easier to confine more particles for a longer time).

I recall having read (several years ago) that the simulation technology of the 90's wasn't really up to the task of aiding in the design of those weird wavy magnets for Wendelstein 7-X, an unfortunate reality which delayed the project a lot.

Re: New records on Wendelstein 7-X

#14

Post by IlikeKitties »

ortusdux wrote: post #8
StevenWaterman wrote: post #7

Earlier quoted context omitted.

Your question reminds me of the image showing how SpaceX raptor motors evolved https://imgur.com/a/4w3q3lS

I'm not keen on the idea of applying a 'keep subtracting things until it blows up' mentality to fusion reactors.

I mean, it's expensive but there's nothing that can happen, they just stop working the nanosecond the environment isn't just right.

Re: New records on Wendelstein 7-X

#15

Post by _joel »

ortusdux wrote: post #8
StevenWaterman wrote: post #7

Earlier quoted context omitted.

Your question reminds me of the image showing how SpaceX raptor motors evolved https://imgur.com/a/4w3q3lS

I'm not keen on the idea of applying a 'keep subtracting things until it blows up' mentality to fusion reactors.

That's not what they're doing though. Reducing manifolds actually improves the durability.

Re: New records on Wendelstein 7-X

#16

Post by dmbche »

bradleyy wrote: post #12

In any future fusion power plant, a plasma with a high triple product must be maintained for long periods. I love vague terms like "long periods". Long compared to the Planck length? Geological time? Is the advertised 43 seconds almost there or "off by 17 orders of magnitude?"

I believe it's "for as long as the reactor is to be operating", and they contrast that with the previous longest times being less than 45 seconds.

Re: New records on Wendelstein 7-X

#17

Post by Miraste »

brohee wrote: post #5

Does it kill the idea of a tokamak as an energy production device? As in a stellarator proving the much more promising design...

I'm no expert, but from the full press release it appears this experiment is the first time they've even been competitive with tokamaks, and are still behind the latest (unpublished) tokamak results.

Re: New records on Wendelstein 7-X

#18

Post by grues-dinner »

xorxornop wrote: post #11
ortusdux wrote: post #8

Earlier quoted context omitted.

I'm not keen on the idea of applying a 'keep subtracting things until it blows up' mentality to fusion reactors.

I wouldn't be concerned about this, personally, for the precise reason that it is a fusion device - not fission! Fusion is incredibly difficult just to start, let alone keep burning - unlike fission, which is only too happy to enter runaway conditions if not very carefully regulated. Fusion is like a little ember in your fireplace you have to carefully blow on to keep alight; fission is like keeping a fireplace lit b…

I'd say (older-generation) fission is more like having an indoor swimming pool filled with burning gasoline, but keeping the windows shut so there's only enough air for it to burn at the rate you want to heat the house.

Re: New records on Wendelstein 7-X

#19

Post by go_elmo »

bradleyy wrote: post #12

In any future fusion power plant, a plasma with a high triple product must be maintained for long periods. I love vague terms like "long periods". Long compared to the Planck length? Geological time? Is the advertised 43 seconds almost there or "off by 17 orders of magnitude?"

Its implict by the context. The co text is SOTA fusion research. One can never fully define everything.

Re: New records on Wendelstein 7-X

#20

Post by GMoromisato »

ortusdux wrote: post #8
StevenWaterman wrote: post #7

Earlier quoted context omitted.

Your question reminds me of the image showing how SpaceX raptor motors evolved https://imgur.com/a/4w3q3lS

I'm not keen on the idea of applying a 'keep subtracting things until it blows up' mentality to fusion reactors.

You could probably summarize the history of bridge-building as "keep subtracting things until they don't stand up anymore."

Building bridges (and large structures in general) has always been about the tension between over-engineering (for safety) and under-engineering (for cost/aesthetics).

The Brooklyn Bridge is massive; they'd never built a bridge like that so they over-engineered it. But once they saw that it was more than strong enough to stand up, the next bridge was lighter. And the next one after that was even lighter. And so on, until a bridge collapses because some new factor came into play (e.g., harmonic resonance).

Source: To Engineer Is Human by Henry Petroski--one of my favorite engineering books.

Post reply on HN