A shot of the pulse from within the reactor:
https://www.youtube.com/watch?v=IMuOaTqdp4c
If you're curious about why the bottom glows: ExB drift pushes electrons to the bottom. I'm sure that doesn't make sense, but unfortunately there isn't really a shortcut to understanding here. Some books are pretty accessible though (I'm a fan of The Future of Fusion Energy).
https://ebrary.net/174598/mathematics/drift_motion_energetic...
And, of course, there is always the freely available IAEA textbook: