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So I heard in the radio today about China's "Artificial sun". There is this hype about it having 5x the temperature of the core of the sun.

It is, as I suspected, a fusion reactor. I admit I do not remember figures by heart, but I recall that in our fusion reactors we typically achieve more temperature but less pressure than the sun itself. At any rate, the challenge is to draw the energy back to energy, and not as much to create these conditions.

So, my question is:

Is that title "Artificial Sun" just marketing, or something that stems from the Chinese language, or does this reactor really have some vast difference than other experimental fusion reactors?

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    $\begingroup$ Yeah, I actually used fission everywhere. Why they made those words so close :S $\endgroup$ Jan 10, 2022 at 8:04

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I think you are asking about EAST, the Experimental Advanced Superconducting Tokamak. You are correct, other experimental fusion reactors have achieved similar temperatures, and the pressures that can be achieved by the National ignition Facility (which uses an inertial confinement process) are much higher. However, the record that was set by EAST in December 2021 was for the duration of the stable plasma pulse that it achieved, which was over 1,000 seconds. The previous duration record, set by the France's Tore Supra reactor in 2018, was 390 seconds.

Being able to maintain a stable plasma for long periods is one of the key requirements for developing a tokamak fusion reactor that can output more power than it consumes.

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Is that title "Artificial Sun" just marketing, or something that stems from the Chinese language, or does this reactor really have some vast difference than other experimental fission reactors?

No, no, and it's complicated.

At least one article about this reactor says tokamaks

are often referred to as "artificial suns" as they are devices that replicate the fusion processes that occur within stars.

(The term might be used for other fusion reactor types too.) Science journalism often eases readers into technical topics: rather than immediately call an X an X, they may first call it something nontechnical or mention a better-known term (e.g. "particles called muons").

EAST achieved several firsts among tokamaks from 2011 onwards, including rapid progress during 2021:

On December 30, 2021, a long-pulse high-parameter plasma operation of 1056 seconds was realized, which once again created a new world record for the operation of the Tokamak experimental device.

Fusion records aren't limited to EAST, or even tokamaks; the other leading reactor type is inertial confinement.

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    $\begingroup$ If we want to be pedantic, (current) tokamak reactors don't replicate the fusion processes that occur within stars. Tokamaks fuse deuterium and tritium, far easier to achieve than even the deuterium-deuterium fusion happening inside brown dwarfs ("failed stars", too light for proper hydrogen fusion of normal stars). So it could be said that "artifical sun" is indeed hyperbole. We're very far from achieving the conditions required for that. $\endgroup$
    – hyde
    Jan 9, 2022 at 18:08
  • $\begingroup$ @hyde Yeah, I don't like the description either. $\endgroup$
    – J.G.
    Jan 9, 2022 at 18:27
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Using "artificial sun" as a pop-sci news way of describing fusion reactors is a very old thing. Here's a reference to it from an April 1976 Popular Mechanics magazine: enter image description here

(found with Google Ngram)

Like almost all science news reporting, the accuracy is much less important than how clickbaity it is. "SCIENTISTS CREATE ARTIFICIAL SUN" sells a lot more magazines (or now, gets more article clicks) than "Scientists raise temp in chamber to xxxx kelvin and create conditions favorable for deuterium tritium reactions blah blah".

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So I heard in the radio today about China's "Artificial sun".

Yes, because it is Chinese and thus gets reported. The many similar reactors out there don't because the USA and Europe are not newsworthy.

There are some interesting things about this reactor, but from a purely technical standpoint it is approximately the same performance as most tokamaks from the 1980s. The JET reactor in the UK has much higher performance. The key difference is that EAST can run for very long periods, which is interesting, but does not really change the underlying physics. The recent record that made the news is related to that long experimental time.

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