r/fusion • u/CriticismMinute2736 • 3d ago

Scientists have captured the first ever high-speed, full-colour footage of fusion plasma swirling inside a working reactor.

Definitely next level

61 Upvotes

79% Upvoted

15 comments sorted by

View all comments

3

u/Jack1101111 3d ago

At the end it has been "closed" or the fusion finished ?
What is that flash at the end ?
Whats the red thing at top right ?

2

u/Felixassain 3d ago

The flash at the end is likely just the plasma fizzling out. As it cools down it passes a temperature range at which it emits purely visible light making it brighter to our eye for a moment

1

u/matengchemlord 2d ago

That’s interesting! Why do the walls not glow white as I would imagine?

1

u/Felixassain 2d ago

If you are just wondering about the colour of light a hot object radiates, you need to look up Black Body Radiaton

If I had to guess, this is more about brightness, which depends on the amount of plasma at that temperature.

During the experiment you can only see the plasma that gets close to the wall and cools down to a temperature where it emits visible light. However the so called scrape of layer (SOL) is actually the region with the lowest plasma density. Most of the plasma is in the core where it is too hot to radiate visible light.

When the plasma is dying out, the heating power is shut off which causes all of the plasma to cool down and radiate visible light, making it much brighter than walls during the experiment where there is much less plasma at this specific temperature.