Re: Overcoupling?

To: tesla-at-pupman-dot-com
Subject: Re: Overcoupling?
From: "Antonio Carlos M. de Queiroz" <acmq-at-compuland-dot-com.br> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)
Date: Fri, 07 May 1999 23:48:01 -0600
Approved: twftesla-at-uswest-dot-net
Delivered-To: fixup-tesla-at-pupman-dot-com-at-fixme

Hi Malcolm:

> - the voltages do get higher at certain values of k as the energy is
> transferred much more rapidly giving the gap less time to lose it

But theoretically this at most produces a small increase in the
secondary voltage, because less energy is lost during the voltage rise.
The voltage profile along the secondary would not change significantly.

> - closer proximity of the primary to the secondary encouraging corona
> formation around the secondary, particularly with raised primaries
> such as conical or helical (I've seen this in small systems)

This is a real possibility. The capacitance to the primary winding
would distort the voltage distribution along the secondary.

> - excitation of spurious resonances causing the secondary to be
> electrically shortened because of the presence of the upper sideband.

Another real possibility. The almost impulsional excitation of the
secondary with high coupling to the primary may transfer significant
energy to higher-order resonant modes.

> I finally had to accept that this is a possibility after Terry's
> current msmt results, much as I don't like the idea. Perhaps this is
> a field ripe for further measurement and exploration to see which
> of the above is correct.

The results showing that there is no significant phase shift between
the current entering the base of the secondary and going to the
terminal are predicted by transmission line theory too. The analog
is a tight rope showing several resonance "arcs" (what is the name?).
All the arcs move at the same time, without phase shift. Only the
amplitude of the oscillations change along the rope (or the coil),
with reversals of direction at each node.

Antonio Carlos M. de Queiroz