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Re: BL saga
Tesla List wrote:
>
> Original Poster: "Malcolm Watts" <MALCOLM-at-directorate.wnp.ac.nz>
>
> Hi all,
> I stuck some charred wood on top of my work coil last
> evening and fired her up. Some bright spots did appear in the
> streamers but you really had to look for them. It would be a bold
> soul that could claim this was ball lightning. They appeared to be
> burining particles of carbon ejected from the charcoal, probably by
> the electric fields. The spots were formed in air streamers and I
> suspect that the considerably brighter attached discharges would all
> but mask the effect. They were not at all long lived and appeared
> only in the streamers.
>
> Malcolm
My gut feel is that ball lightning must include some aspect of a fuel
being burned (or particles being incandescent), just because a plasma
would cool too fast by radiation. I'd talked to Jim Corum a year or so
ago and he mentioned his tesla coil work with metal particles in an air
stream and with sooty flames.
Subsequently, I've played around a bit with high energy sparks (several
kJ) in metal particle clouds and through soot. (Trying to build a
visual simulacrum of the "death ray", don't you know...)
You get really striking effects from injecting soot (or small chemical
dust particles of various kinds) into a free burning arc (like in a big
jacobs ladder), including glowing blobs, etc. However, they aren't
controllable.
One of the best ways to make a sooty flame is to burn a carbon rich fuel
in a rich mixture. Acetylene in air makes such a sooty flame that it not
only has copious black smoke, but little soot particles, which the arc
ignites. Propylene also works, but not as well. In the special effects
business, a common technique to create black smoke that is moderately
controllable is to burn a mixture of naphthalene and diesel oil (don't
breath the fumes!!!!, particularly after extinguishing it and the
naphthalene vapors are condensing in a very pretty cloud of crystals).
You put it in a small metal container (like a sterno can?) that you can
cover with a lid to extinguish it. Rubber cement also burns with a nice
yellow sooty flame, that is tough to extinguish with blowing air. It is
easy to ignite, too, because the solvent is hexane.
Dr. Corum mentioned that they had built a quarter wave coaxial
transmission line (two concentric) a few feet long fed from a moderate
power RF amplifier which would generate a pretty steady plasma discharge
at the hv points. I've always thought that you might be able to do
somthing like feed your sooty mixture through the coax line in "puffs"
to generate ring vortices which are made of incandescent soot.
Certainly, one can generate the ring vortices this way. I just don't
know if the soot would entrain, and also be heated by the RF discharge.