Mystery Plasma Tube Identified

[Eidetical]

Six years ago I found the obviously old and very weird looking laser tube below that nobody I talked to could identify. We figured it was an RF-excited argon ion tube, and it turns out that was right. Just now I was looking through the September 1968 issue of Laser Focus magazine just put on the shelf here thanks to fellow holographer Ed Wesly and I found a "New Product" announcement for the Spectra-Physics model 141 "Easy Argon Laser" with a picture of the tube and the head it goes in. What a treat! It's also featured on the back cover. A Spectra-Physics sticker on the base says it's model SP-061, but there's another label under that one. I don't want to risk removing the top one.