Re: Color Fades in discharges

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: FIFTYGUY@xxxxxxx 


    Interesting stuff, Mike!
    I would think one of the first things to do would be to put gases of 
known composition into your big discharge tube. Probably start with just 
pure N2, O2, CO2, Ar, H2O, O3, NOx's, etc, just for control. Then see what 
happens to a discharge in pure N2 as you add a trace of the others. Maybe 
by finding out what isn't getting "burnt" will help nail down what is.
    I think by our minimum BPS for long sparks that there's some 
time-dependent effect that lasts only a few mS to allow the streamers to 
extend. A lifetime of a "burnt" product in the air?
    Might be interesting to also run a Tesla coil discharge through your 
discharge tube before and after you "burn" the air (and other gases).
    One wonders if the "burning" is actually due to heating by the arc, 
ionization of the gas, UV or other radiation, or a chemical reaction with 
something that IS a direct product of the discharge. Simulating the 
temperature of an arc without an arc might be tough, but could you 
illuminate/irradiate gas in the discharge tube first by exposing it to a 
discharge in a sealed but transparent adjacent chamber? Or could you 
introduce pure O3 and/or NOx's into the chamber until the air behaves "burned"?
    Whatabout doing your burning in short bursts, to minimize the 
long-term heating effects? Is it still the same cumulative time to burn a 
mixture as it takes to burn it all at once?
    Seems like an easy thing for us hobbyists to experiment with, as the 
color change is permanent, visible anywhere near standard conditions, and 
is apparent in ordinary air. Heck, it's not even dependent on RF, AC, or 
DC! Unfortunately, it may be pretty important to exclude trace contaminants.
    Obviously, plasma globes don't "burn" their contents in a few minutes. 
Fluorescent, neon, and HID lights also last a while (although metal-halide 
lights do undergo a major color change early and late in their lives, and 
this probably due to a completely different effect?). Gas tubes don't wear 
out that quick, do they? Thyratrons and such last for a while, at least. So 
what's different about air and these gases? Doesn't oxygen "poison" plasma 
globes effectively?
    This sounds neato. I'll play with this a bit and report back...

-Phil LaBudde