How Come Early CRTs contained more Ions?

[cwmoser]

Originally Posted by Reece

... Older tubes had their electron guns "bent" so they didn't shoot straight. The ion trap had magnet(s) that bent the beam back straight during operation of the tube. Since ions aren't bent by magnetism, they went off at the preset angle and impacted the side of the tube neck, doing no damage. ...

I've understand that the ION Magnet should be adjusted to the brightest image. I backed mine off slightly from maximum brightness to eliminate shadows on the edge of the picture tube. I assume this is OK considering that the ions still will not hit the phosphorous because the electron gun shoots out deflected?

Then I have heard that if you don't adjust the ION magnet just right, it will mark the center of the picture tube.

Comments?