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Comment by jetru | Hacker News Reader

Skeptical. This video by Sabine clearly explains why a lot of these fusion research claims are dubious with a focus on ITER and JET: https://www.youtube.com/watch?v=LJ4W1g-6JiY

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Not dubious claims, misleading claims. ITER is designed with the goal of achieving Qplasma=10, which is energy break-even, but not electricity break-even, which as Sabine points out is at around Qplasma=20 (for ITER specifically, had it been designed to achieve electricity, in theory).

That Sabine has a point that some media outlets miscommunicated the Qtotal, it does not mean every article that does not mention Qtotal is somehow a scam. Qtotal is only relevant for project in which achieving a positive Qtotal is actually a goal, which it isn't for any of these projects.

What Sabine doesn't mention is what the theoretical limit of Qplasma actually is. ITER was explicitly designed for Qplasma>=10 to save costs. There's no other reason why Qplasma couldn't be higher. It's just money that is the limit.

People quoting Sabine should get this in their head, ITER was not designed for generating electricity. Its Qtotal is intentionally lower than 1. Yes there have been journalists who got important details in their articles wrong, but anyone who knows anything about these reactors is not being mislead by the ITER or JET experiments.

Moreover she communicates that to achieve the desired goal, Qtotal is the one that must exceed 1, and that is harder to achieve. That is, total electrical energy generated to exceed total energy to run the system. You have losses down the road, particularly when converting heat to electricity.

It doesn't take away from research that is being done/must be done, but rather how far we are today from the results.

> JET’s latest experiment sustained a Q of 0.33 for 5 seconds, says Rimini. JET is a scaled-down version of ITER, at one-tenth of the volume — a bathtub compared to a swimming pool, says Proll. It loses heat more easily than ITER, so it was never expected to hit breakeven. If engineers applied the same conditions and physics approach to ITER as to JET, she says, it would probably reach its goal of a Q of 10, producing ten times the energy put in.

"If engineers applied the same conditions and physics..."

"...probably reach its goal of a Q of 10..."

So casually thrown about!

Source (the OP nature article): https://www.nature.com/articles/d41586-022-00391-1

Worth noting she makes several mistakes in her analysis, although her point stands she is likely over estimating the detla.

As this video is always posted on threads about fusion I'll just link to the last time it came up.

https://news.ycombinator.com/item?id=30271677&p=2#30273453

Agreed. She really did a great job explaining how the progress of fusion research is regularly miscommunicated to the public as more significant or quickly applicable than it actually is.

Fusion in general seems like a false hope for any of our near term energy problems.

Spark notes on issues: Lies by omission.

- No mention of lawson criterion performance.

- Only 3 nuclear MCF machines ever (ie that even have a Q).

- Conflates MCF machines with ICF machines (ICF machines are funded under DoE's "nuclear stockpile maintenance" line item, not energy research).

- No mention of plasma self-heating. ITER is 50% shy of lawson criterion performance necessary for a Q=infinity reactor (if it were a stellarator).

Came here to post this. Thanks for your service. Sabine explains clearly the problems while still advocating for Fusion research to continue.

I would really like to see her discuss the MIT SPARC reactor.

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