Look like nobody else has heard of this either!
When I read your post , I thought "what a super idea !!!" .... Knowing what a pain it the butt it could sometimes be to find an Ion Trap's perfect position , I would have loved it if all the CRTs of the olden days had that ....
Now , that being said , , I'd never heard of it before your post , , and have no direct experience to share of it .... If you DO find one of these CRTs , and get good pictures of the purposfully glowin neck , I'd love to see em