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Re: Looking for demo ideas for TC

Original poster: Jim Lux <jimlux@xxxxxxxxxxxxx>

At 03:52 PM 1/6/2005, you wrote:
Original poster: "Mike" <mikev@xxxxxxxxxxxxxxxx>

Hi Chip, List
                        I know the mean free path is an issue, so I don't
know about at 760 Torr (Sea level) pressure. I'm told the neon sign people
pump down to ~ 10 millitorr then add the neon.

With neon tubes, it's not so much the mean free path (although that figures in) but it's that you want to be well onto the left side of the Paschen curve, so that you get a glow discharge and not an arc. The minimum breakdown voltage is (for many gases, although I don't recall for Ar) at a pressure around 5-10 torr. As the pressure gets lower, the breakdown voltage gets higher.

You can also get a glow discharge at higher pressures, where the electrode geometry is such that it promotes the glow regime and not the arc regime.

 Then again, as the TC has a
whole lot of voltage, you may get the gas to swing through higher orbits
then back to ground state. At ~100 Millitorr I get a distance of 6 feet
between electrodes going with ~ 1100 volts then ~185 volts maintains the
glow. You can do the argon test easy in that these days the lower power
house bulbs are argon back filled at a pretty high pressure, don't know how
close to sea level.. If you can get one going in the TC field that may be
useful. You can also get one going nice in the microwave oven, metal and
all. Watch it else it will melt the glass if left in too long. That could be
the even open filament going or the gas.