jimlux wrote:
On 2/7/11 7:07 AM, Bert Hickman wrote:David Steinberg wrote:Thank you all for your suggestions. I'm considering the glass enclosure with argon gas. As I've never worked with glass enclosures or argon before, I have a couple of questions: 1. What length of arc should I expect?The breakdown and reignition voltage of argon is considerably lower than air, and an argon arc will typically be ~5X the length of an arc in air under identical conditions.that much longer? I never seem to get that... twice is the best I've been able to do. Maybe it's convection/electrode shape/heating dependent? I haven't tried a jacob's ladder in argon, just a drawn arc between two hemispheres or conical points.
You may be correct. The Ayrton arc equation predicts a 2-3X enhancement based upon expected voltage drop across the arc for low-current DC arcs (and likely for 60 Hz as well). The actual degree of enhancement undoubtedly depends on the electrode materials, configuration, shape, etc. My 5X estimate came from my notes from many years back, based upon a communication with a CA coiler. The initial breakdown voltage for argon is about 15% that of air (i.e., a spark in argon will jump about 6X as long as in air) but it must be relatively pure argon (i.e., much less than 1% O2).
The enhancement effect is apparently greater at higher frequencies. For example, Bill Beaty reported that a 1" long air TC discharge became one foot long white, snake-like discharges in argon. He also warns against using argon-CO2 mix, since CO2 apparently poisons the mix. See:
http://amasci.com/tesla/heli1.htmlThis suggests that powering the argon ladder from an electronic NST or other HF source may provide better performance than a 60 Hz NST.
Bert -- ******************************************************************** We specialize in UNIQUE items: coins shrunk by ultra-strong magnetic fields, Captured Lightning Lichtenberg figure sculptures, and scarce technical Books. Please visit us at http://www.capturedlightning.com ******************************************************************** _______________________________________________ Tesla mailing list Tesla@xxxxxxxxxx http://www.pupman.com/mailman/listinfo/tesla