I just recently found a local neon sign maker and asked him to make me a
simple vacuum tube, which he did, gratis (!). It's 18 inches long, clear
glass tubing about 3/4 inch in diameter, with electrodes at opposite ends. I
don't know how hard a vacuum he pulled on this, but very quick tests show a
pale blue glow from end to end. A strong magnet placed next to the tube
pinches the beam, intensifying it at the spot.
I've not run this for more than a few seconds. I am concerned about x-rays.
I'd like advice about operating this tube safely.