Large top loads

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Original poster: "Jim Mora" <jmora@xxxxxxxxxxx>

Hello all,

I am building a demo coil that will eventually be mobile on a trailer (three
phase 15kva generator and dc). In the mean while, I will be using a neon
bombardier 14400v. I have been modeling with Java 9.1, as this is outside
and local factors are nill, besides I like it!

The coil form is 1/8? pvc 12.25? (31.115cm) diameter and is at presently 6
feet tall. The primary will be ½?(1.27cm) soft copper tubing spaced 1/2 with
a 2?(5.08cm) arc space btw the coil and the first turn. K=.133.

Here?s the question: What are the practical limits of the top load? I plan
to wind the coil 68 inches (172.72cm). 18 awg magnet (1.024mm) - wire
reactance 30K. Ratio 5.55, 30 dc ohms. The toroid will be 60?(152.4cm) x
12?(30.4cm) I will likely glue a 4?(10.16) toroid under it as a arc shield.
Why the big ratios and still enjoy the bang of a reasonably large Pri cap? I
want as much windings as I can get into the primary. The cap is a MMC (15)
strings of (18).15 CD?s .125uf fair on hold off excellent on temp rise. I
plane to leave room on the mmc form to add 3 more strings and five more caps
per string if needed.

Here what?s interesting: If a place a 32?(81.28cm) toroid in the center of
top and say a large colander on top of that (essentially a 24?(60.96cm)
spheroid which is what I first tried, the mutual inductance goes >  425 and
the primacy inductance gets up to 97 and 11 turns out!

Probably this would all work better with a fatter coil, but this is what
I?ve got and my budget is tapped on this.

Jim Mora

I have no problem using a breakout (may need one for safety sake anyway),
but I followed this logic with my first coil and didn't need one at all. I
got the idea of adding more on top from a toroid full of water and wet
leaves and retuning out to 15.

I already have a 1"(2.54) square wood truss system in my mind for the toroid
support. Two separated by 6"(15.24cm) like spokes in a wheel complete with
45 degrees joining two wood disks in the center with a 1/2" (1.27cm) hard
copper 6" pipe epoxied to except a .5" all thread fiberglass threaded into
the top plate or pipe extensions. The circles would be cardboard covered in
aluminum foil ... Should be light and very strong...Thumb tacked or glued to
completion. The nice thing about additional top load is they are just set
there.

Ok, please poke some hole in this where needed! I know there have to be
trade offs!