Tesla Coil - Internal Arcing on Secondary

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Original poster: Brady Hauth <bhauth@xxxxxxxxx>

I've just finished a 1 kw 1/4 wave tesla coil, off a 7 stage marx
generator off of a microwave oven transformer. 3J pulses in PP snubber
caps. Far too much work - I removed the secondary on some signal
transformers for inductive separation between stages, and it took a
couple tries to figure out a workable spark gap system. I ended up
using concrete bolts with wire wrapped around the threading and vise-d
together. Problem is, now the secondary is arcing. The secondary is
~700 turns of 22 awg wire on a 6 in diameter acrylic tube, spacewound
at the top and the bottom, with 3 spray coats and 1 brush coat of
polyurethane on it after winding. The topload is 25.75 pf (calculated)
and the secondary is 21.3mh (experimental) for resonance at ~215kHz.
The winding is about 19 inches, spacewound above and below that.The
primary is inside the secondary, on a 3 inch diameter tube. The arcing
seems to happen at a consistent place. The arcing is clearly between
the secondary's wire and the acrylic form; it is so bright it shines
through the enamel clearly, making a cool looking lightning pattern
just under the wire. Any ideas on how to stop the arcing? I can draw
off maybe 6 inches of spark, but I should get 6-8 times that according
to my figuring.