Re: How to rise the secondary? (fwd)

---------- Forwarded message ----------
Date: Sat, 25 Jul 1998 12:16:55 -0700
From: "Antonio Carlos M. de Queiroz" <acmq-at-compuland-dot-com.br>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: How to rise the secondary? (fwd)

John H. Couture wrote:

>   Theoretically you could go a 10 ft beyond the arc-over point and it would
> only take more time to transfer the energy and would produce the same spark
> length. However, if the tuning is inseparable from the coupling then there
> would be a reduction in spark length because tuning affects the amount of
> energy transferred.

The tuning affects the coupling, as it affects the geometry of the system and
the primary inductance, but just moving the secondary does not affect the
inductances. If it changes the tuning the reason must be due to changes in
parasitic capacitances. The main reason why the energy transfer decreases to
far below the ideal theoretical value if the secondary is moved too far away
from the primary is because the primary field couples to other "receptors"
nearby, and little energy effectively reaches the secondary.

>   There have been hundreds of articles in the past that have tried to
> explain how a Tesla coils works. All of these articles ignore many details
> that indicates we still have a lot to learn about Tesla coil operation and
> design. When it comes to magnifiers we are only in a primitive testing stage
> so empirical design is not possible. It could turn out that when we learn
> how to design the optimun classical Tesla coil the magnifier will not be
> required.

I don't think so. A Tesla coil, or a magnifier, is a very simple device,
and there are no problems at all in modeling how it works with the known theory.
With very little theory it is perfectly possible to build one that works,
as effectively there is no optimum design, or the optimum is very broad, and
in most cases it is possible to reach the optimum by just tuning one or two 
points (primary tuning and coupling).
The theoretical problem is how to obtain accurately the correct parameters to 
model the several distributed affects in these devices. And consider also that 
the main objective is to produce sparks, that are a very randomic phenomenom,
subject to subtle influences from many factors.

Antonio Carlos M. de Queiroz