Re: Acmi k x turns

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

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

Antonio Carlos M. de Queiroz