Capacitive Transformer "maxed out"?

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

Original poster: "Jolyon Vater Cox by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jolyon-at-vatercox.freeserve.co.uk>


Capacitive Transformer Maxed Out?

For L2 in my capacitive transformer TC I am currently using a vitamin pill 
tube 1 1/8" in diameter wound to a length of 5 1/4" with 40SWG enamelled 
copper wire; the wire tables say that 40 SWG is 189 turns per inch 
(close-wound) so max number of turns is likely to be 992.25 turns which by 
Wheeler s formula gives 54411.8733 uH.

By the way, a picture of my TC is posted at 
http://hot-streamer-dot-com/temp/capxfrmr.jpg on the Tesla list.

I initially designed the setup as a transformerless TC with k and l equal 
to 9 and 10 respectively; the inductance of L1 being approximately equal to 
62uH.

The longest spark I have drawn from it is about 1 inch to a pointed 
terminal when a 3 3/8" disc is used as the topload.

I have allowed a hole diameter of 2 1/4" between the influence ring and L2 
and have wrapped a length of 15/1000" thick plastic sheet inside this hole 
to act as a spark preventer; I still get corona around the inner edge of 
the ring however. Would widening the hole be beneficial or detrimental to 
performance?

I have tried much bigger caps (salt-water caps made from pop-bottles of 
300ml upwards as well as 250ml food containers) these gave very poor 
performance even when the topload was made larger to compensate. Does this 
mean that my design has reached the limit of what is possible?

I have another former 4 3/4" tall and 2 1/8 in diameter. Suppose I wound 
this with 40SWG to a length of 4 1/4" I would have 803.25 turns and 
13990.535 uH.

If I kept k and l ratio of 9:10 and designed a new L1 accordingly would I 
likely get longer sparks than at present?