My friend Jon Singer sent me a link to this fellow’s homebrewed Panaplex display, using a jam jar as the vacuum chamber. Panaplex is a kind of gas-discharge plasma display tech related to the Nixie tube. The builder, Lindsay Wilson, explains the basic setup for his display:
The entire thing is based on using a jam jar as a vacuum chamber. Each of the cathode electrodes is made from a 2cm length of copper wire. A stainless steel M3 screw is soldered to the middle of the wire. This allows it to be screwed to the support plate, which is made from a piece of ceramic tile. It was very easy to drill the 3mm holes with a diamond drill – the tile is made from sintered ceramic powder and is quite soft. A solder tag is mounted on the back of each cathode screw which allows electrical connection to be made to the respective cathode.
For an electrical feedthrough, I was lucky enough to have two multi-pin feedthroughs I found in a skip a few years ago. These are quality jobs – circular Amphenol connectors and proper glass/metal hermetic seals around the pins. The support plate with the electrodes is mounted on the main body of the electrical feedthrough.
An insulating collar sits between the feedthrough flange and the jam jar. The anode grid is mounted on this and is made from a piece of aluminium window screen. A gas inlet and vacuum line are also connected to the collar. I made the collar from PVC which is probably the worst material possible for vacuum use, but it did alright.
Finally, the jam jar sits on top of the collar with a piece of inner tube acting as a gasket.