What gasses conduct electricity relatively easily. I know that it takes about 30 000v to ionise 1 centimeter of air. Is there another gass that would ionise more easily?
Look to the periodic table of the elements. Elements along the left hand side have a single electron in their outermost shell. Of these elements only hdrogen is a gas. On the exreme right hand side are the inert elements. Many of them are gases. They are hard to ionize because their outermost electron shells are full. The column to the left consists of elements that are one electron away from having their outermost shell complete. Add an electron and you'll have a negative ion, on the cheap so to speak.
Yea, target temperature is important.. It gets really complex when you move from atomic/diatomic gases into more complex molecular stuff.. HID lighting info would probably impart quite a bit of the knowledge you seek..
Google "high pressure sodium"/"low pressure sodium", "metal halide", "fluorescent", "mercury lamp"..
BTW, some incandescent bulbs are filled with vacuum, while others are filled with inert gases.. This has nothing to do with gas conductivity at all, so ignore that..
Any flame will conduct. It is an ionized gas, so by definition it is a conductor.
A gas in a low pressure environment ionizes easily, which turns it into a conductor. This is true of most gases. This is what makes flourescents and a lot of lasers work.
The gas used in photo-flash tubes for your camera gear. It will conduct the instant discharge of a 350vdc x 200 - 20K microfarad capacitor. Those make for some nasty shocks !!
Main trouble, is the ionzing trigger voltage must be anywhere from 2 - 4 Kv.
Playing around with this stuff, is capable of killing you outright !! Odds are you will never know what hit you !
I've been clobbered twice in 20 ~ years experience with flash units. It ain't no fun.