Yes, but the really hot part is not emitting visible light. ;)

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:

https://www.iaea.org/publications/8879/fusion-physics