Paschen's Law ( Curve )-Effect of a Vacuum on a High Voltage Arc

In this demo, I am going to hook up my high voltage ignition coil-light dimmer power supply to a home made vacuum chamber. The power supply can put out a good 3 ½ inch electrical arc at atmosphere. In theory, based on the concept of Paschen's Curve, as you reduce the atmosphere by pulling a vacuum, it is easier and easier to draw an arc at ever increasing distances as you pull the vacuum deeper. This phenomena reverses itself, and arc length shortens at around one torr. . Depending on the gas, some are easier to draw a longer arc than others (See my videos where I pulled arcs in helium at atmosphere, which was another demonstration of Paschen's Curve ). In this video I am pulling the vacuum in the everyday air we breath, which is mostly nitrogen (followed by oxygen).

The vacuum pump pulled the vacuum quickly and is rated to 40 millitorrs, but I don't believe I got close to that number.

Note towards the end of the video where I disconnect the vacuum hose from the pump and the vacuum chamber begins to pressurize to atmosphere. Notice how the arc changes shape from a fatter fuzzy consistency to a thin tight arc before it breaks down.

It appears that I could have created a much longer arc than 6 ½ inches if I built a bigger vacuum chamber. (Maybe I'll do that and video it. Let me know if you do it first so I can see how it works.)