Re: More Coupling...

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

Original poster: "Luc by way of Terry Fritz <twftesla-at-uswest-dot-net>" <ludev-at-videotron.ca>

Hi Antonio

It's hard for me to explain myself in english sometime. What I mean is
using a flat secondary on top of a flat
primary, separate by a good insulator and driving a tertiary coil from this
secondary. I'm sure you can wind a flat
secondary :example a spiral of 22 AGW 20" wide close wound; 370 turns,
sitting on top of a regular primary ( 1/4"
copper tube space wound 20" diameter ). I'm not sure but I think you have
enough coupling ( easy to adjust just play
with separation ) and I remember in a previous discussion about secondary
shape Terry or an other one said cone
secondary are not efficient but it could by interesting to try an inverse
cone ( a relation between voltage increase
along the coil at the same time the  inductance increase ) and a flat
spiral is an inverse cone at is maximum.

Luc Benard
P.S. excuse my English I hope I'm enough clear on this one.

Tesla list wrote:

> Original poster: "Antonio Carlos M. de Queiroz by way of Terry Fritz
<twftesla-at-uswest-dot-net>" <acmq-at-compuland-dot-com.br>
>
> Tesla list wrote:
> >
> > Original poster: "Luc by way of Terry Fritz <twftesla-at-uswest-dot-net>"
> <ludev-at-videotron.ca>
> >
> > Naturally I mean pancake ...ops!
>
> An efficient magnifier requires a precise coupling, and a rather tight
> one. The structure of the magnifier is justified precisely due to the
> requirement of high coupling. A normal Tesla coil with k=0.6
> (energy transfer in 1 cycle) is problematic due to intense electric
> fields between primary and secondary due to their small distance,
> that I believe to be the reason of the "racing sparks" phenomenon.
> A solution is to move away the high-voltage upper section of the
> secondary, resulting in the magnifier structure. But this requires
> even higher coupling in the primary-secondary system if the result
> is to be equivalent to a Tesla coil with k=0.6. The high coupling
> also adds a significant capacitance between the primary and the
> secondary, and its effect must be taken into account. The result is
> a required coupling coefficient between primary and secondary of
> 0.67. This would be obtained with a solenoidal primary with a diameter
> that is about 1.3 times greater than the secondary diameter, and
> the same height. A flat primary would not reach a so high coupling.
>
> Antonio Carlos M. de Queiroz