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Major breakthrough on nuclear fusion energy

bbc.co.uk

21–30 of 827 posts

Re: Major breakthrough on nuclear fusion energy

#21
post #7

Earlier quoted context omitted.

This could be read as an either pro or anti-brexit comment but the fact that it is ambiguous makes it kind of pointless.

If you can read that as a pro-Brexit comment, then the Brexit project succeeded beyond its instigators' wildest dreams. It's not ambiguous at all. Everything in the UK going on right now -- everything -- has a "some of this is unclear or worse because Brexit has destroyed agreements or because proposed, nearly impossible agreements have not been struck" subplot. Brexit has set fire to every kind of international comp…

You do realise that countries can work together without being part of the same trading block?

... If I understand your nonsensical ramblings correctly.

Re: Major breakthrough on nuclear fusion energy

#22
post #9
post #6

> The experiments produced 59 megajoules of energy over five seconds (11 megawatts of power). > This is more than double what was achieved in similar tests back in 1997. > It's not a massive energy output - only enough to boil about 60 kettles' worth of water. But the significance is that it validates design choices that have been made for an even bigger fusion reactor now being constructed in France. I thought this…

Is it possible they subtracted the energy required to facilitate the reaction in the first place? So net energy was enough to boil 60 kettles worth of water?

"At Jet, two 500 megawatt flywheels are used to run the experiments."

So net power is -989MW, assuming both flywheels are at full pelt the whole time and no power is required before fusion is acheived.

Re: Major breakthrough on nuclear fusion energy

#23
post #20
post #6

> The experiments produced 59 megajoules of energy over five seconds (11 megawatts of power). > This is more than double what was achieved in similar tests back in 1997. > It's not a massive energy output - only enough to boil about 60 kettles' worth of water. But the significance is that it validates design choices that have been made for an even bigger fusion reactor now being constructed in France. I thought this…

>In fact, it takes 4,184 joules to raise the temperature of 1kg of water by 1 degree. Or 313800 joules to raise 1kg of water by 75 degrees. That means JET could have boiled about 188 kg of water. This is missing the heat of vaporization[1] needed to actually boil the water though, i.e. to turn 100C liquid water to 100C steam. That's another 2250kJ/kg on top of the 313.8kJ/kg you've mentioned. It's why steam is such a…

[deleted]

Re: Major breakthrough on nuclear fusion energy

#24
post #20
post #6

> The experiments produced 59 megajoules of energy over five seconds (11 megawatts of power). > This is more than double what was achieved in similar tests back in 1997. > It's not a massive energy output - only enough to boil about 60 kettles' worth of water. But the significance is that it validates design choices that have been made for an even bigger fusion reactor now being constructed in France. I thought this…

>In fact, it takes 4,184 joules to raise the temperature of 1kg of water by 1 degree. Or 313800 joules to raise 1kg of water by 75 degrees. That means JET could have boiled about 188 kg of water. This is missing the heat of vaporization[1] needed to actually boil the water though, i.e. to turn 100C liquid water to 100C steam. That's another 2250kJ/kg on top of the 313.8kJ/kg you've mentioned. It's why steam is such a…

> I guess you could argue that you wouldn't evaporate all water in the kettle...

One does not have to argue for that interpretation - raising the temperature to boiling point, not boiling it dry, is indisputably the accepted and intended meaning of the phrase wherever English is spoken... though it would fit with a certain stereotype of scientists if a bunch of plasma physicists did not know how to make a pot of tea!

Re: Major breakthrough on nuclear fusion energy

#25
post #6

> The experiments produced 59 megajoules of energy over five seconds (11 megawatts of power). > This is more than double what was achieved in similar tests back in 1997. > It's not a massive energy output - only enough to boil about 60 kettles' worth of water. But the significance is that it validates design choices that have been made for an even bigger fusion reactor now being constructed in France. I thought this…

That calculation is correct if you assume that by "boil water" they mean to bring the water to 100°C (which is what you'd use a kettle for usually).

However to go from liquid water to water vapor you need to add even more energy [0]. The enthalpy of vaporization for water is 2257 kJ/kg, it takes much more energy to boil water at 100°C than it takes to get there from room temperature.

Warming by 75 degrees + boiling = 2570 kJ/kg -> enough to boil 23 liters of water

I'm guessing in reality the energy needed to operate the kettles would lie somewhere in between, as a small part of the water will be boiled and most of it kept around 100°C. For 2L kettles the value seems in the right ballpark.

[0] https://en.wikipedia.org/wiki/Enthalpy_of_vaporization

Re: Major breakthrough on nuclear fusion energy

#26

Earlier quoted context omitted.

If you can read that as a pro-Brexit comment, then the Brexit project succeeded beyond its instigators' wildest dreams. It's not ambiguous at all. Everything in the UK going on right now -- everything -- has a "some of this is unclear or worse because Brexit has destroyed agreements or because proposed, nearly impossible agreements have not been struck" subplot. Brexit has set fire to every kind of international comp…

You do realise that countries can work together without being part of the same trading block? ... If I understand your nonsensical ramblings correctly.

> ... If I understand your nonsensical ramblings correctly.

If you think they are nonsensical, you do not understand what I am saying.

Yes, countries can "work together without being part of the same trading bloc" but trade is not the limit of what Brexit changed.

Brexit removes us from the international legal agreements that underpinned that trade. It also removed us from the free movement clause, which is crucial to a lot of science-industry collaborations (the free movement principle was essentially invented to allow professional collaboration in the energy industry).

Finally it also removed us from the legal frameworks that underpin several European science funding agreements.

Every agreement has to be rewritten, at cost to the process. And every time it is rewritten, the net result for Britain is substantially worse than if we'd not done it. Because you cannot hope to get full membership of any club without agreeing to all the rules.

From the article:

> The UK is a participant, too. Its full involvement in ITER, however, will require first for Britain to "associate" to certain EU science programmes, something that so far has been held up by disagreements over post-Brexit trading arrangements, particularly in relation to Northern Ireland.

Here is just one example of that:

https://www.theguardian.com/politics/2022/feb/08/uk-and-euro...

From that article:

> The EU agreed to associate membership for the UK as part of the wider Brexit trade deal struck on Christmas Eve 2020 but it has still not ratified the deal or a similar one with Switzerland, held up by a dispute over a draft treaty binding the country to the bloc.

We didn't need to do any of this, there have been no benefits from any of this, and there are no meaningful projected benefits for any of this in our lifetimes.

Re: Major breakthrough on nuclear fusion energy

#27

Earlier quoted context omitted.

If you can read that as a pro-Brexit comment, then the Brexit project succeeded beyond its instigators' wildest dreams. It's not ambiguous at all. Everything in the UK going on right now -- everything -- has a "some of this is unclear or worse because Brexit has destroyed agreements or because proposed, nearly impossible agreements have not been struck" subplot. Brexit has set fire to every kind of international comp…

You do realise that countries can work together without being part of the same trading block? ... If I understand your nonsensical ramblings correctly.

It's not a binary thing. It's not either they work together or they don't.

Under a common block, trading or otherwise, things are just easier and much closer together.

Consider only visas, travel and employment, the complications of these brought by Brexit already distanced any existing and future collaborations by some measure.

There is still collaboration of course, and there will be, but it's not what it was before.

And this negative trend of distance in collaboration is more worrying in an increasingly threatening environment

Re: Major breakthrough on nuclear fusion energy

#29
post #9

Earlier quoted context omitted.

Is it possible they subtracted the energy required to facilitate the reaction in the first place? So net energy was enough to boil 60 kettles worth of water?

"At Jet, two 500 megawatt flywheels are used to run the experiments." So net power is -989MW, assuming both flywheels are at full pelt the whole time and no power is required before fusion is acheived.

Those are used for the confinement coils. Incredibly, JET uses copper coils. You can't run those all day, so the flywheels are used. The last machine I worked at worked the same way. 16 train motors with 1 ton flywheels spinning at 1600 RPM to be an 11 MW power supply for 1 second every few minutes.

Plasma heating in JET is done via NBI+ICRH and is about 59 MW.

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