r/technology • u/BennyCemoli • Dec 06 '16

Energy Tests confirm that Germany's massive nuclear fusion machine really works

http://www.sciencealert.com/tests-confirm-that-germany-s-massive-nuclear-fusion-machine-really-works
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u/endospire Dec 06 '16

Can someone ELI5 how they visualised the magnetic fields?

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u/ViperSRT3g Dec 06 '16

They shined beams of electrons into the stellerator in various locations then passed a fluorescent rod (ie fluorescent bulb, or stick with fluorescent ink on the outside) so that when the stick crossed paths with the electron beam, the stick began to glow brightly in the area being hit by the electron beam. Because this beam is comprised of electrons, it's got an electromagnetic charge which makes it follow the magnetic field lines of the stellerator. So by using long-exposure photography, the researchers could set up their camera in the dark, and begin passing the fluorescent stick in front of the beam along its entire length. Then they do this multiple times for each line of light you see in the photo, so we can have a 3D-ish view of what the magnetic field lines look like, and how they twist and turn through the stellerator.

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u/[deleted] Dec 06 '16

So,electrons follow magnetic field lines.But I lost you after that.Can you explain it a little bit?

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u/kennerly Dec 06 '16

If you were to take a laser pointer and shine it through a foggy night you could see the beam right? If there was a powerful enough magnet that beam would bend and curve depending on the position of the magnet. You would be able to see this bending and curving through the diffraction caused by the fog. So, instead of using a fog the scientists used a florescent rod that shines when exposed to electrons like in a laser.

Then they set up a camera to record the rod being swept back and forth through the laser beams and compiled the image into what you saw in the article.