KeithPickering wrote:

And why are there so many apparent filaments at the top and bottom? Isn’t the number of filaments equal to the number of outer Copper electrodes?

The filaments are created in counter-rotating pairs, with one pair per outer cathode. So the number of filaments is 2 x electrodes.

See this image:

https://focusfusion.org/index.php/gallery/image_med/6/

I’ve been misinterpreting the slideshow. Glad the question was raised.