Re: More Coupling...

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

Original poster: "Ed Phillips by way of Terry Fritz <twftesla-at-uswest-dot-net>" <evp-at-pacbell-dot-net>

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

	A friend of mine built such a high k system at TRW, in connection with
a million-volt (really 10^6 volts) pulse project.  It worked OK but was
a lot of work to get set up right.  Do you know of any approximate
method for calculating the mutual inductance for a flat primary?  I
suppose one could do it by computing M for each of the turns and then
summing it, but that sounds like a lot of work and have never tried it.

	I see a lot of fellows using flat primaries, and wonder how much
coupling they actually get.

Ed