I found a book talking about vacuum feedthrough in aon old schoolroom. It was a very interesting concept. I cannot believe that you can use such a ting to apply so many things to a vacuum environment. Those vacuum pumps they were describing were amazing in their own right, much less with the added feedtrhough. But,I am really nor sure how the whole thing works, but i am sure I could figure out at least the basic concept. I am interested in getting into this field, so I guess I better start trying to figure out what those terms mean, or I will be in a mess.