Re: Acmi k x turns

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

Original poster: "Malcolm Watts by way of Terry Fritz <twftesla-at-qwest-dot-net>" <m.j.watts-at-massey.ac.nz>

Hi Antonio,

On 28 Sep 2002, at 19:48, Tesla list wrote:

> Original poster: "Antonio Carlos M. de Queiroz by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <acmq-at-compuland-dot-com.br>
> 
> Tesla list wrote:
> > 
> > Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> <Parpp807-at-aol-dot-com>
> 
> > Antonio and Paul,
> > 
> > Interesting discussion.  Is there an optimum degree of coupling between the
> > turns
> > of a coil so that k will range from an under to an over-coupled condition?
> 
> There is nothing in the dynamics of a Tesla coil that can be
> called "overcoupling". This term come originally from doubly tuned
> circuits used in radiofrequency filters, where excessive coupling
> leads to a frequency response with only one peak instead of two.
> A Tesla coil operates in a completely different way, always deep
> in the "undercoupled" condition. An equivalent "overcoupling"
> condition would result in an excessively lossy system.
> 
> The term has been used in "coiling" to denote the point where
> sparking between primary and secondary occurs, or when "racing 
> sparks" appear, but these problems are insulation problems, not 
> directly related to a particular coupling coefficient.
> 
> The observation that only the dimensions of the two coils, and not
> their number of turns, affect k is very interesting, and I have
> not seen this mentioned before.

No? I've forgotten the number of times I've said this. The proof is 
in some of my posts in the archives. The results of many measurements 
brought me to this conclusion. It was later confirmed when Dr 
Rszesotarksi's MandK program based on Neumann Integrals (I think) 
correctly confirmed the measurements. 

 A simple formula
> for k based on the geometry of the coils alone must then exist.

Agreed.

> This also adds some simple constraints on the geometry of the coils, 
> if the design is to be aimed at a particular value of k.

Also agreed.

Regards,
malcolm