Arc Over Between Secondary and Primary Coils

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "tmoore by way of Terry Fritz <twftesla-at-qwest-dot-net>" <tmoore-at-erie-dot-net>

Hello Everyone,

    This is Nolan I have been working on a new mini tesla coil that I just
finished building.  My mini coil specs are

Secondary:  2.375 in diameter by 15in high wound with Awg 28 12.75 in long
10 or more coats of polyurethane
Primary: 6awg ground wire 0.25in spaced between turns max turn 8.75 1in
spaced from secondary
Topload: Toroid length is 9.5in and 3.375 cord, made from flexible Al tubing
wrapped 3 times in Al tape
Cap: Maxwell pulse discharge 0.03uf rated at 35kv
Spark gap:  single static gap .25in carriage bolts set at 0.15in just below
transformers max spark length
Power Supply: Franceformer 7500kv at 60ma

    My problem it that I am getting massive arc over from the middle of the
secondary coil to the primary.  I noticed that when I had sparks coming off
the topload to a grounded object 8in or close that there was no mid
secondary to primary coil ark over at all.  When I move the grounded object
away and let sparks go in to the free air I get tons of arc over.  Is this
because the grounded object doesn't let enough energy to be stored and thus
there is no arc over? Anyway I need a solution!  I was thinking about
removing a turn or two from the primary, one turn would make the distance
about 1.4in and tow turns removed would be about 1.8in, but I would be
getting low on turns.  Would .4in or .8in more solve my ark over problem?
If not any tips or suggestions that would help are greatly appreciated. Also
I found that when I adjust the spark gap smaller and sand the electrodes
every time, this greatly reduces arc over but also diminishes the spark
length off the topload. Any ideas on spark gap? Thanks for your help!

Sincerely,
Nolan Moore